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Advancing Human Development: Theory and Practice

Human development is a process of enlarging people’s choices.

Frances Stewart

Professor emeritus of development economics at the university of oxford, emma samman.

Frances Stewart is Professor Emeritus of Development Economics at the University of Oxford and Emma Samman is a Research Associate at the Overseas Development Institute

'Human development is a process of enlarging people’s choices. The most critical ones are to lead a long and healthy life, to be educated and to enjoy a decent standard of living. Additional choices include political freedom, guaranteed human rights and self-respect' (HDRO 1990).

The Human Development approach insists that the fundamental aim of development policy should be to expand the opportunities that people have to lead meaningful lives. Economic growth is a means towards this end, not an end in itself. As an overarching objective, the approach gained prominence with the publication of UNDP’s first Human Development Report in 1990.

The approach developed as a response to the almost exclusive emphasis development policymakers had given to economic growth and stabilization. It came out of a long sequence of proposals reacting to the social ills resulting from this emphasis, which included high levels of poverty, deficient education and health services, high inequality and unemployment. Human development was the most effective (belated) response to economist Dudley Seers’ cry to ‘dethrone’ GNP. It built, in particular, on the Basic Needs approach, which prioritizes the satisfaction of fundamental necessities for living, and Amartya’s Sen’s capability approach, which focuses on peoples’ freedom to advance valued goals.

In Advancing Human Development: Theory and Practice by Frances Stewart, Gustav Ranis and Emma Samman (OUP 2018) which has just been published, we explain the origins of the idea of Human Development and its relationship with alternative objectives including the maximization of societal happiness and the pursuit of economic growth. (Two of the authors, the late Gustav Ranis and Frances Stewart, were part of the team responsible for the first Human Development Report and in one way or another were associated with virtually every subsequent Report.) The book provides a global overview of progress in the many dimensions of human development over the past forty years, while considering why some countries have been much more successful than others in improving their human development status.

We look beyond basic human development as measured by the well-known Human Development Index (HDI) to other dimensions of human flourishing. We pay particular attention to the role of social institutions (including norms and organizations) and social capabilities in advancing human development, and identify some of the political factors which lead to success. Finally, we consider what is needed to ensure the continued relevance and significance of the Human Development approach.

Among our findings:

• While economic growth should not be the prime objective of development, it is an important input into advancing human development. At the same time improved Human Development is essential for sustained economic growth.
• Consequently, we find countries in virtuous and vicious cycles of development, where good (or poor) human development and economic growth reinforce one another.
• Dimensions of human development beyond the basic ones encapsulated by the HDI include political freedoms, societal cohesion, the reduction of inequalities, and environmental factors, among others. These non-HDI dimensions are NOT well-correlated with the HDI: countries can do well on the HDI yet poorly on other dimensions.
• Social institutions and social capabilities, which tend to be neglected by individualistic approaches such as that of neo-classical economics and much of the capabilities work are an integral part of individual flourishing, as well as critical inputs into Human Development.
• In a small number of countries, some combination of ideology, commitment and collective action underpin exceptional leaps in human development, as in Thailand where over the last four decades, income poverty fell more than 40 percentage points, secondary education enrolment more than doubled and infant mortality fell by a factor of six.
• There is no single route to success; some countries give priority to growth while sustaining the social sectors; others give social expenditure prime emphasis and succeed despite moderate or low growth. Similarly, the prime agents of change also differ: in some countries, such as Ethiopia, the government leads with the support of aid; in others, it is a combination of progressive bureaucrats and politicians; and in rare cases (Bangladesh), NGOs are prime agents. But all success cases show impressive progress on gender equality and female empowerment.
• Despite substantial progress both on basic human development and on many other dimensions, there has been less progress or even regress on important dimensions, including aspects of societal wellbeing, inequalities, and above all environmental factors.

Lastly, we highlight three challenging problems which need addressing, both through advancing theory and better policies. The first is macro-economic policies for promoting human development – currently, macro-policies tend to restrict progress, often holding back expenditures on the social sectors because of austerity policies, and generating inegalitarian growth and unsatisfactory employment outcomes.

The second problem is that of reducing inequalities, which are excessive in most parts of the world. These can undermine societal cohesion (sometimes leading to violent conflict), slow poverty reduction and weaken the sustainability of economic growth. Yet current policies tend to increase rather than reduce inequalities.

The third and most important challenge concerns environmental issues, such as climate change, which are likely greatly to weaken the human development of future generations. Here too, many policies are tending to worsen rather than improve the situation.

We argue that these are the priorities for future research, measurement, and policy analysis. Without progress in each, our present achievements on human development may prove to be ephemeral.

The HDialogue blog is a platform for debate and discussion. Posts reflect the views of respective authors in their individual capacities and not the views of UNDP/HDRO.

HDRO encourages reflections on the HDialogue contributions. The office posts comments that supports a constructive dialogue on policy options for advancing human development and are formulated respectful of other, potentially differing views. The office reserves the right to contain contributions that appear divisive.

Photo: Oxford University Press

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2.3: Understanding Theories

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Learning Outcomes

• Describe theories as they relate to lifespan development
• Describe the historical foundations leading to the development of theories about lifespan development

A theory guides and helps us interpret research findings as well. It provides the researcher with a blueprint or model to be used to help piece together various studies. Think of theories are guidelines much like directions that come with an appliance or other object that required assembly. The instructions can help one piece together smaller parts more easily than if trial and error are used.

Theories can be developed using induction in which a number of single cases are observed and after patterns or similarities are noted, the theorist develops ideas based on these examples. Established theories are then tested through research; however, not all theories are equally suited to scientific investigation. Some theories are difficult to test but are still useful in stimulating debate or providing concepts that have practical application. Keep in mind that theories are not facts; they are guidelines for investigation and practice, and they gain credibility through research that fails to disprove them.

What is a theory?

In l ifespan development, we need to relying on a systematic approach to understanding behavior, based on observable events and the scientific method. There are so many different observations about childhood, adulthood, and development in general that we use theories to help organize all of the different observable events or variables. A theory is a simplified explanation of the world that attempts to explain how variables interact with each other. It can take complex, interconnected issues and narrow it down to the essentials. This enables developmental theorists and researchers to analyze the problem in greater depth.

Two key concepts in the scientific approach are theory and hypothesis. A theory is a well-developed set of ideas that propose an explanation for observed phenomena that can be used to make predictions about future observations. A hypothesis is a testable prediction that is arrived at logically from a theory. It is often worded as an if-then statement (e.g., if I study all night, I will get a passing grade on the test). The hypothesis is extremely important because it bridges the gap between the realm of ideas and the real world. As specific hypotheses are tested, theories are modified and refined to reflect and incorporate the result of these tests. In essence, lifespan theories explain observable events in a meaningful way. They are not as specific as hypotheses, which are so specific that we use them to make predictions in research. Theories offer more general explanations about behavior and events.

Think of theories are guidelines much like directions that come with an appliance or other object that required assembly. The instructions can help one piece together smaller parts more easily than if trial and error are used.

Theories can be developed using induction, in which a number of single cases are observed and after patterns or similarities are noted, the theorist develops ideas based on these examples. Established theories are then tested through research; however, not all theories are equally suited to scientific investigation. Some theories are difficult to test but are still useful in stimulating debate or providing concepts that have practical application. Keep in mind that theories are not facts; they are guidelines for investigation and practice, and they gain credibility through research that fails to disprove them.

People who study lifespan development approach the it from different perspectives. Each perspective encompasses one or more theories—the broad, organized explanations and predictions concerning phenomena of interest. Theories of development provide a framework for thinking about human growth, development, and learning. If you have ever wondered about what motivates human thought and behavior, understanding these theories can provide useful insight into individuals and society.

Throughout psychological history and still in present day, three key issues remain among which developmental theorists often disagree. Particularly oft-disputed is the role of early experiences on later development in opposition to current behavior reflecting present experiences–namely the passive verses active issue . Likewise, whether or not development is best viewed as occurring in stages or rather as a gradual and cumulative process of change has traditionally been up for debate – a question of continuity versus discontinuity. Further, the role of heredity and the environment in shaping human development is a much contested topic of discussion – also referred to as nature/nurture debate . We’ll examine each of these issues in more detail throughout the course.

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History of Developmental Psychology

The scientific study of children began in the late nineteenth century, and blossomed in the early twentieth century as pioneering psychologists sought to uncover the secrets of human behavior by studying its development. Developmental psychology made an early appearance in a more literary form, however. William Shakespeare had his melancholy character, “Jacques” (in As You Like It), articulate the “seven ages of man,” which included three stages of childhood and four of adulthood.

Three early scholars, John Locke, Jean-Jacques Rousseau, and Charles Darwin proposed theories of human behavior that are the “direct ancestors of the three major theoretical traditions” of developmental psychology today(Vasta et al, 1998, p. 10). Locke, a British empiricist, adhered to a strict environmentalist position, that the mind of the newborn as a tabula rasa (“blank slate”) on which knowledge is written through experience and learning. Rousseau, a Swiss philosopher who spent much of his life in France, proposed a nativistic model in his famous novel Emile , in which development occurs according to innate processes progressing through three stages: Infans (infancy), puer (childhood), and adolescence. Rousseau detailed some of the necessary progression through these stages in order to develop into an ideal citizen. Although some aspects of his text were controversial, Rousseau’s ideas were strongly influential on educators at the time. Finally, the work of Darwin, the British biologist famous for his theory of evolution, led others to suggest that development proceeds through evolutionary recapitulation, with many human behaviors having their origins in successful adaptations in the past as “ontogeny recapitulates phylogeny.”

G. Stanley Hall

Darwin’s theories greatly influenced G. Stanley Hall, who believed that children developed over their lifetime much in the same way that a species evolved throughout time. His interests focused on childhood development, adolescence, and evolutionary theory. His major contributions to the field are that he taught the first courses in child development, several of his students becoming leading researchers in the field, and he established scientific journals for the publication of child development research. He was also the first president of the American Psychological Association.

James Mark Baldwin

Another early contributor to the study of development was James Mark Baldwin (1861-1934), a Princeton educated American philosopher and psychologist who did quantitative and experimental research on infant development. He made important contributions to early psychology, psychiatry, and to the theory of evolution. Baldwin wrote essays such as “Mental Development in the Child and the Race: Methods and Processes”, which made a vivid impression on Jean Piaget (who later developed the most popular theory of cognitive development) and Lawrence Kohlberg (who developed a theory about moral judgment and development).

John B. Watson

The 20th century marked the formation of qualitative distinctions between children and adults. When John Watson wrote the book Psychological Care of Infant and Child in 1928, he sought to add clarification surrounding behaviorists views on child care and development. Watson was the founder of the field of behaviorism, which emphasized the role of nurture, or the environment, in human development. He believed, based on Locke’s environmentalist position, that human behavior can be understood in terms of experiences and learning. He believed that all behaviors are learned, or conditioned, as evidenced by his famous “Little Albert” study, in which he conditioned an infant to fear a white rat. In Watson’s book on care of the infant and child, Watson explained that children should be treated as a young adult—with respect, but also without emotional attachment. In the book, he warned against the inevitable dangers of a mother providing too much love and affection. Watson explained that love, along with everything else as the behaviorist saw the world, is conditioned. Watson supported his warnings by mentioning invalidism, saying that society does not overly comfort children as they become young adults in the real world, so parents should not set up these unrealistic expectations. His book (obviously) became highly criticized, but was still influential in promoting more research into early childhood behavior and development.

Sigmund Freud

Another name you are probably familiar with who was influential in the study human development is Sigmund Freud. Sigmund Freud’s model of “psychosexual development” grew out of his psychoanalytic approach to human personality and psychopathology. In sharp contrast to the objective approach espoused by Watson, Freud based his model of child development on his own and his patients’ recollections of their childhood. He developed a stage model of development in which the libido, or sexual energy, of the child focuses on different “zones” or areas of the body as the child grows to adulthood. Freud’s model is an “interactionist” one, since he believed that although the sequence and timing of these stages is biologically determined, successful personality development depends on the experiences the child has during each stage. Although the details of Freud’s developmental theory have been widely criticized, his emphasis on the importance of early childhood experiences, prior to five years of age, has had a lasting impact.

Arnold Gesell

Arnold Gesell, a student of G. Stanley Hall, carried out the first large-scale detailed study of children’s behavior, authoring several books on the topic in the 1920s, 30s, and 40s. His research revealed consistent patterns of development, supporting his view that human development depends on biological “maturation,” with the environment providing only minor variations in the age at which a skill might emerge but never affecting the sequence or pattern. Gesell’s research produced norms, such as the order and the normal age range in which a variety of early behaviors such as sitting, crawling, and walking emerge. In conducting his studies, Gesell developed sophisticated observational techniques, including one-way viewing screens and recording methods that did not disturb the child.

Jean Piaget

Jean Piaget (1896-1980) is considered one of the most influential psychologists of the twentieth century, and his stage theory of cognitive development revolutionized our view of children’s thinking and learning. His work inspired more research than any other theorist, and many of his concepts are still foundational to developmental psychology. His interest lay in children’s knowledge, their thinking, and the qualitative differences in their thinking as it develops. Although he called his field “genetic epistemology,” stressing the role of biological determinism, he also assigned great importance to experience. In his view, children “construct” their knowledge through processes of “assimilation,” in which they evaluate and try to understand new information, based on their existing knowledge of the world, and “accommodation,” in which they expand and modify their cognitive structures based on new experiences.

Modern developmental psychology generally focuses on how and why certain modifications throughout an individual’s life-cycle (cognitive, social, intellectual, personality) and human growth change over time. There are many theorists that have made, and continue to make, a profound contribution to this area of psychology, amongst whom is Erik Erikson who developed a model of eight stages of psychological development. He believed that humans developed in stages throughout their lifetimes and this would affect their behaviors. In this module, we’ll examine some of these major theories and contributions made my prominent psychologists.

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[glossary-page] [glossary-term]hypothesis:[/glossary-term] [glossary-definition]a testable prediction[/glossary-definition]

[glossary-term]theory:[/glossary-term] [glossary-definition]a well-developed set of ideas that propose an explanation for observed phenomena that can be used to make predictions about future observations[/glossary-definition] [/glossary-page]

Contributors and Attributions

• Modification, adaptation, and original content. Authored by : Sonja Ann Miller for Lumen Learning. Provided by : Lumen Learning. License : CC BY-SA: Attribution-ShareAlike
• Psyc 200 Lifespan Psychology. Authored by : Laura Overstreet. Located at : http://opencourselibrary.org/econ-201/ . License : CC BY: Attribution
• Hall Freud Jung in front of Clark 1909. Provided by : Wikimedia. Located at : https://commons.wikimedia.org/wiki/File:Hall_Freud_Jung_in_front_of_Clark_1909.jpg . License : CC BY: Attribution
• Information on Stanley Hall. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/G._Stanley_Hall . License : CC BY-SA: Attribution-ShareAlike
• Emilie, or On Education. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/Emile,_or_On_Education . License : CC BY-SA: Attribution-ShareAlike
• Information on James Mark Baldwin. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/James_Mark_Baldwin . License : CC BY-SA: Attribution-ShareAlike
• John B. Watson. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/John_B._Watson . License : CC BY-SA: Attribution-ShareAlike
• Section on the history of developmental psychology. Provided by : New World Encyclopedia. Located at : http://www.newworldencyclopedia.org/entry/Developmental_psychology . License : CC BY-SA: Attribution-ShareAlike
• Information on theory and hypothesis. Provided by : Lumen Learning. Located at : https://courses.lumenlearning.com/waymaker-psychology/chapter/reading-the-scientific-process-replace-content/ . License : CC BY: Attribution
• Applied History of Psychology Controversies. Provided by : Wikipedia. Located at : https://en.wikibooks.org/wiki/Applied_History_of_Psychology/Controversies . License : CC BY-SA: Attribution-ShareAlike

IResearchNet

Theories of Human Development

This article delves into the multifaceted world of human development theories, exploring the intellectual legacies of prominent theorists who have shaped our understanding of how individuals grow and change over the lifespan. It provides an insightful journey through the Psychoanalytic Perspective, elucidating the stages of psychosexual development as conceptualized by Sigmund Freud and the psychosocial stages of Erik Erikson. The Cognitive Development Perspective delves into the cognitive maturations posited by Jean Piaget and the sociocultural framework introduced by Lev Vygotsky. The article also navigates the Behavioral and Social Learning Perspective, encompassing the principles of operant conditioning by B.F. Skinner and the observational learning theory of Albert Bandura. As we conclude, we reflect on the enduring relevance and contemporary applications of these developmental theories in the ever-evolving landscape of psychology.

Introduction

The field of human development is an intricate tapestry woven from the threads of biology, psychology, sociology, and culture. It is the study of how individuals evolve physically, cognitively, and emotionally as they progress from infancy to old age. It seeks to unravel the mysteries of human growth, transformation, and the intricate interplay between nature and nurture.

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Understanding the theories of human development is of paramount importance in various realms of science, education, healthcare, and beyond. These theories serve as guiding beacons, illuminating the pathways along which human beings journey throughout their lives. By comprehending the underlying principles and frameworks that underpin the developmental process, we gain insights into the fundamental questions of who we are, how we become who we are, and why we act as we do.

The purpose of this article is to embark on a journey through the intricate landscape of human development theories. We will delve into the theoretical constructs put forth by eminent psychologists, unveiling the core tenets of their philosophies and the stages they postulate for human maturation. Specifically, this article is structured to explore three prominent perspectives: the Psychoanalytic Perspective, the Cognitive Development Perspective, and the Behavioral and Social Learning Perspective. Each perspective has given rise to a unique set of concepts and ideas that provide windows into the mysteries of human development.

In the following sections, we will begin by examining the Psychoanalytic Perspective, which includes the groundbreaking work of Sigmund Freud and Erik Erikson. We will then navigate the Cognitive Development Perspective, shedding light on the cognitive milestones proposed by Jean Piaget and the sociocultural insights of Lev Vygotsky. Finally, we will venture into the realm of the Behavioral and Social Learning Perspective, where the operant conditioning principles of B.F. Skinner and Albert Bandura’s observational learning theory take center stage. Together, these perspectives offer a comprehensive overview of the theories that have shaped our understanding of human development, and they continue to influence fields as diverse as psychology, education, and clinical practice.

The Psychoanalytic Perspective

The Psychoanalytic Perspective represents a pivotal paradigm in the realm of human development, fostering an intricate understanding of the inner workings of the human mind and the progression of human personalities over time. Within this perspective, two seminal figures emerge—Sigmund Freud and Erik Erikson—each contributing distinctive theories that have played a significant role in shaping our comprehension of developmental processes.

Sigmund Freud’s Psychosexual Theory:

Sigmund Freud, the Austrian neurologist and father of psychoanalysis, introduced the Psychosexual Theory of development. This theory postulates that human development unfolds in a series of psychosexual stages, each characterized by a unique focus on specific erogenous zones and conflicts that must be resolved. Freud’s work in the late 19th and early 20th centuries has left an indelible mark on psychology and beyond.

Freud’s psychosexual theory consists of five key stages:

Oral Stage (0-1 years) : In this initial stage, an infant’s pleasure is centered on oral activities like sucking and biting. The primary conflict involves weaning from the breast or bottle, and the successful resolution leads to trust and autonomy.

Anal Stage (1-3 years) : During this stage, children derive pleasure from controlling their bowel movements. The primary conflict pertains to toilet training, and the resolution shapes the child’s sense of self-control and order.

Phallic Stage (3-6 years) : This phase is marked by the emergence of the Oedipus and Electra complexes. Children develop sexual desires for the opposite-sex parent and experience rivalry with the same-sex parent. The resolution of these conflicts plays a crucial role in the formation of the superego.

Latency Stage (6-12 years) : In this stage, sexual desires remain dormant, and children focus on developing social and intellectual skills. The resolution of earlier conflicts contributes to psychological health.

Genital Stage (12+ years) : This final stage represents mature adult sexuality, where individuals seek to satisfy their sexual desires through relationships with others. The successful resolution of the earlier stages is thought to facilitate healthy, loving relationships.

While Freud’s work revolutionized our understanding of the unconscious mind and its impact on human behavior, it is not without its critics and limitations. Many contemporary psychologists challenge the emphasis on sexual and aggressive drives in human development, as well as the notion of unconscious conflicts. Critics argue that his theory is overly focused on male experiences and neglects the role of cultural and social factors.

Nonetheless, Freud’s contributions to psychology are undeniable. He pioneered the exploration of the unconscious and laid the groundwork for the psychoanalytic approach to therapy. His work on defense mechanisms, dream analysis, and the structure of the mind has left a lasting legacy, impacting both psychology and popular culture.

Erik Erikson’s Psychosocial Theory:

Erik Erikson, a German-American psychoanalyst, expanded upon Freud’s ideas and introduced the Psychosocial Theory of development. In contrast to Freud’s focus on the early years of life, Erikson proposed that development unfolds across the entire lifespan, with a total of eight stages, each associated with a unique psychosocial crisis.

Erikson’s eight stages of psychosocial development are as follows:

Trust vs. Mistrust (0-1 year) : In infancy, the central conflict is between developing trust in caregivers and a sense of mistrust. Successful resolution leads to hope and confidence.

Autonomy vs. Shame and Doubt (1-3 years) : Toddlers assert their independence and develop a sense of autonomy or face feelings of shame and doubt.

Initiative vs. Guilt (3-6 years) : In the early childhood years, children grapple with the conflict between taking initiative and experiencing guilt.

Industry vs. Inferiority (6-12 years) : The school-age years focus on the development of a sense of industry and competence.

Identity vs. Role Confusion (12-18 years) : Adolescents explore their identities and grapple with questions of who they are and what roles they will occupy.

Intimacy vs. Isolation (18-40 years) : Young adults seek intimacy and meaningful relationships, or they may experience isolation.

Generativity vs. Stagnation (40-65 years) : Middle-aged adults confront the need for generativity, which includes making a lasting contribution to society.

Integrity vs. Despair (65+ years) : In the final stage, older adults reflect on their lives, either experiencing a sense of integrity or despair.

Erikson’s theory has garnered substantial recognition for its lifespan approach, which highlights the ongoing nature of human development. It underscores the importance of psychosocial challenges throughout life and the potential for personal growth and development in later years. Critics, however, contend that his theory is somewhat vague and that the stages are not always universally applicable to all individuals.

Despite these critiques, Erikson’s contributions to developmental psychology are notable. His focus on identity, relationships, and the interplay of societal and cultural influences continues to influence psychological research and clinical practice, making his theory a valuable addition to the field of human development.

The Cognitive Development Perspective

The Cognitive Development Perspective focuses on how individuals acquire, process, and utilize information as they mature. This perspective encompasses theories that delve into cognitive growth, and two prominent theorists who have significantly impacted our understanding of cognitive development are Jean Piaget and Lev Vygotsky.

Jean Piaget, a Swiss psychologist, introduced the Cognitive Development Theory, which is characterized by the concept of cognitive stages. According to Piaget, children progress through four distinct stages, each marked by qualitative changes in their cognitive abilities and understanding of the world.

The stages in Piaget’s theory are as follows:

Sensorimotor Stage (0-2 years) : During this stage, infants explore the world through their senses and motor actions. They develop object permanence, the understanding that objects continue to exist even when they are out of sight.

Preoperational Stage (2-7 years) : In this stage, children become capable of symbolic thought and language development. However, their thinking is often egocentric and characterized by animism and centration.

Concrete Operational Stage (7-11 years) : Children in this stage can perform operations on concrete objects and think logically about concrete situations. They develop conservation and reversibility abilities.

Formal Operational Stage (11+ years) : Adolescents and adults at this stage can think abstractly, engage in hypothetical and deductive reasoning, and grapple with complex moral dilemmas.

Jean Piaget’s theory has had a profound impact on educational psychology and child development. His emphasis on the active role of children in their own cognitive development has greatly influenced teaching and learning strategies. However, Piaget’s theory has also faced criticism for underestimating the cognitive abilities of children and adolescents, as well as for not accounting for cultural and individual differences in development.

Despite these critiques, Piaget’s work continues to be a foundational framework for understanding how children think and learn. His research into the cognitive development of children laid the groundwork for a host of subsequent studies in this area and has enduring relevance in educational and developmental psychology.

Lev Vygotsky, a Soviet psychologist, introduced the Sociocultural Theory of cognitive development. This theory posits that social interaction and cultural context play a fundamental role in cognitive growth. According to Vygotsky, development occurs through a process known as the “zone of proximal development” (ZPD), where children can learn with the help of more knowledgeable individuals.

The central tenets of Vygotsky’s theory include:

The Zone of Proximal Development (ZPD) : This concept defines the range of tasks a learner can perform independently and the tasks they can accomplish with guidance or assistance from a more knowledgeable person.

Scaffolding : Scaffolding is the process by which a more knowledgeable individual provides support to a learner, gradually reducing this support as the learner becomes more capable of completing tasks independently.

Cultural Tools : Vygotsky emphasized the role of cultural tools, such as language, in shaping thought and development. He believed that language serves as a crucial means for thought and learning.

Vygotsky’s Sociocultural Theory has garnered praise for its emphasis on the role of social interaction, culture, and language in cognitive development. It has been particularly influential in educational practices, as it highlights the importance of collaborative learning and the role of the teacher as a facilitator of learning.

Critics have argued that Vygotsky’s theory might overemphasize the role of social interaction at the expense of individual cognitive processes. Additionally, some have questioned the universality of his ideas, suggesting that they may not be applicable to all cultural contexts.

Nonetheless, Vygotsky’s contributions to the understanding of cognitive development, particularly in the context of cultural influences and educational practices, continue to shape the field of psychology and education, with his concepts serving as valuable tools for both researchers and educators.

The Behavioral and Social Learning Perspective

The Behavioral and Social Learning Perspective focuses on the external influences and experiences that shape human development, emphasizing the role of behavior and social interaction. Within this perspective, two influential theorists, B.F. Skinner and Albert Bandura, have contributed significantly to our understanding of how individuals learn and develop through their interactions with the environment.

B.F. Skinner, an American psychologist, is renowned for his development of the theory of operant conditioning, which posits that behavior is influenced by the consequences that follow it. Skinner’s work, carried out in the mid-20th century, has had a profound impact on the fields of psychology and education.

The principles of Skinner’s operant conditioning theory can be summarized as follows:

Reinforcement : Skinner introduced the concept of reinforcement, which involves providing consequences that strengthen the likelihood of a specific behavior occurring again. Positive reinforcement involves presenting a desirable stimulus, while negative reinforcement involves removing an aversive stimulus.

Punishment : In contrast to reinforcement, punishment aims to weaken or reduce the occurrence of a behavior. Positive punishment involves introducing an aversive stimulus, while negative punishment involves removing a desirable stimulus.

Extinction : If a behavior is no longer reinforced, it may eventually cease to occur. This process is known as extinction.

Schedules of Reinforcement : Skinner explored various schedules of reinforcement, including fixed-ratio, variable-ratio, fixed-interval, and variable-interval schedules, each affecting the frequency and pattern of behavior differently.

B.F. Skinner’s operant conditioning theory has had a significant impact on the field of psychology, especially in the realm of behavior modification and therapy. Critics, however, argue that it oversimplifies the complexity of human behavior and cognition. It has also been criticized for its lack of attention to cognitive processes and emotions, which play vital roles in human development.

Nonetheless, Skinner’s principles of operant conditioning have practical applications in various settings, including education, clinical psychology, and behavior management. His work has been instrumental in shaping behavioral interventions, and his ideas continue to influence the development of new therapeutic techniques and classroom strategies.

Albert Bandura, a Canadian-American psychologist, introduced the Social Cognitive Theory, which emphasizes the reciprocal relationship between cognitive processes, behavior, and the environment. Bandura’s work, which gained prominence in the mid-20th century, has illuminated the role of observational learning and self-regulation in human development.

The key components of Bandura’s theory include:

Observational Learning : Bandura proposed that individuals can acquire new behaviors and information by observing and imitating the actions and behaviors of others. This process is often referred to as social learning or modeling.

Self-Efficacy : Bandura introduced the concept of self-efficacy, which pertains to an individual’s belief in their ability to perform specific tasks and achieve goals. High self-efficacy is associated with increased motivation and persistence.

Reciprocal Determinism : Bandura highlighted the dynamic interplay between personal factors, behaviors, and the environment. This mutual influence underscores the complexity of human development.

Albert Bandura’s Social Cognitive Theory has had a profound influence on various fields, including education, psychology, and social sciences. His emphasis on observational learning has enriched our understanding of how children and adults learn through modeling and imitation.

Critics argue that Bandura’s theory might understate the role of innate factors and the influence of emotions in shaping behavior. Nonetheless, his work has led to the development of therapeutic techniques such as cognitive-behavioral therapy, which utilizes concepts like self-efficacy to promote positive change in individuals.

In contemporary psychology, Bandura’s ideas continue to provide a valuable framework for understanding how individuals learn, develop, and adapt to their surroundings, with his work remaining instrumental in shaping educational practices, psychotherapy, and the study of human development.

In this comprehensive exploration of developmental theories, we have navigated through three prominent perspectives that have significantly shaped our understanding of human growth and behavior. The Psychoanalytic Perspective, pioneered by Sigmund Freud and Erik Erikson, delves into the intricate interplay between early life experiences and the development of personality. The Cognitive Development Perspective, as articulated by Jean Piaget and Lev Vygotsky, has illuminated the cognitive milestones and the role of social interaction in the journey from infancy to adulthood. The Behavioral and Social Learning Perspective, exemplified by B.F. Skinner and Albert Bandura, underscores the impact of external influences, conditioning, and observational learning on human development.

The relevance of these developmental theories in understanding human behavior and growth cannot be overstated. These theories provide vital frameworks for comprehending the multifaceted processes that individuals undergo as they traverse the stages of life. They have been instrumental in fields such as psychology, education, and clinical practice, informing strategies for learning, therapy, and behavioral intervention.

Nevertheless, it is essential to acknowledge that the field of developmental psychology is not static. Ongoing debates and the evolution of developmental theories continue to shape the landscape of research and practice. Contemporary discussions explore the interplay between nature and nurture, the cultural and contextual factors that influence development, and the potential impact of emerging technologies. As our understanding of human development deepens, so too will the theories that seek to explain this intricate journey, contributing to a more comprehensive and nuanced perspective on the growth and transformation of individuals from birth to old age. In this ever-evolving field, these foundational theories provide the essential building blocks for future research, fostering a richer comprehension of the human experience.

References:

• Freud, S. (1905). Three essays on the theory of sexuality. Standard Edition, 7, 123-246.
• Erikson, E. H. (1950). Childhood and society. Norton & Company.
• Piaget, J. (1952). The origins of intelligence in children. International Universities Press.
• Vygotsky, L. S. (1978). Mind in society: The development of higher psychological processes. Harvard University Press.
• Skinner, B. F. (1938). The behavior of organisms. Appleton-Century-Crofts.
• Bandura, A. (1977). Social learning theory. Prentice-Hall.
• McLeod, S. (2020). Erik Erikson’s psychosocial theory of development. Simply Psychology. [URL]
• Santrock, J. W. (2019). Life-span development. McGraw-Hill Education.
• Wood, D., Bruner, J. S., & Ross, G. (1976). The role of tutoring in problem solving. Journal of Child Psychology and Psychiatry, 17(2), 89-100.
• Schaffer, H. R. (2009). Social development. Wiley-Blackwell.

What is Developmental Psychology?

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Learn about our Editorial Process

Olivia Guy-Evans, MSc

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Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

On This Page:

Developmental psychology is a scientific approach that aims to explain growth, change, and consistency though the lifespan. Developmental psychology examines how thinking, feeling, and behavior change throughout a person’s life.

A significant proportion of theories within this discipline focus on development during childhood, as this is the period during an individual’s lifespan when the most change occurs.

Developmental psychologists study a wide range of theoretical areas, such as biological, social, emotion, and cognitive processes.

Empirical research in this area tends to be dominated by psychologists from Western cultures such as North American and Europe, although during the 1980s Japanese researchers began making a valid contribution to the field.

• Maturation in psychology refers to the natural developmental process driven by genetics, leading to physical, behavioral, and psychological growth independent of learning or experience.
• The idiographic approach focuses on understanding unique, individual differences in experiences or behaviors, often using qualitative methods.
• Normative development in psychology refers to the typical sequence and timing of developmental milestones that most people experience within a population.

The three goals of developmental psychology are to describe, explain, and optimize development (Baltes, Reese, & Lipsitt, 1980).

Finally, developmental psychologists hope to optimize development, and apply their theories to help people in practical situations (e.g. help parents develop secure attachments with their children).

Continuity vs. Discontinuity in Human Development 

Think about how children become adults. Is there a predictable pattern they follow regarding thought and language and social development? Do children go through gradual changes or are they abrupt changes?

Normative development is typically viewed as a continual and cumulative process. The continuity view says that development is a smooth and gradual accumulation of abilities, with one stage flowing seamlessly into the next.

Children become more skillful in thinking, talking, or acting much the same way as they get taller.

It assumes that changes are incremental, with skills and knowledge building upon what was previously learned. The analogy often used to describe this perspective is viewing development as a slope or ramp, gradually inclining upwards.

The discontinuity view sees development as a more abrupt-a succession of changes that produce different behaviors in different age-specific life periods called stages. Biological changes provide the potential for these changes.

These stages are believed to be qualitatively different, each bringing a dramatic shift in abilities or behaviors.

Theorists like Jean Piaget and Erik Erikson support this perspective. They argue that children pass through distinct stages at certain ages, and the qualities of each stage are significantly different from those of other stages. This can be visualized as steps on a staircase.

We often hear people talking about children going through “stages” in life (i.e., “sensorimotor stage.”). These are called developmental stages-periods of life initiated by distinct transitions in physical or psychological functioning.

Psychologists of the discontinuity view believe that people go through the same stages, in the same order, but not necessarily at the same rate.

Stability vs. Change in Human Development

Stability implies personality traits present during infancy endure throughout the lifespan. It emphasizes the importance of early experiences on future development, suggesting that early childhood experiences play a significant role in determining adult personality traits and behaviors.

For example, a child who is cheerful and outgoing will likely grow into an adult with similar personality traits. Stability theorists believe that change is relatively difficult once initial personality traits have been established.

In contrast, change theorists argue that family interactions, school experiences, and acculturation modify personalities.

It implies that our behaviors, thoughts, and emotions are malleable and can be influenced by experiences and environments over time. This perspective suggests that it is equally likely for an introverted child to become an extroverted adult, depending on various factors such as life experiences, education, or trauma.

This capacity for change is called plasticity. For example, Rutter (1981) discovered that somber babies living in understaffed orphanages often become cheerful and affectionate when placed in socially stimulating adoptive homes.

Nature vs. Nurture

When trying to explain development, it is important to consider the relative contribution of both nature and nurture . Developmental psychology seeks to answer two big questions about heredity and environment:

• How much weight does each contribute?
• How do nature and nurture interact?

Nature refers to the process of biological maturation, inheritance, and maturation. One of the reasons why the development of human beings is so similar is because our common specifies heredity (DNA) guides all of us through many of the same developmental changes at about the same points in our lives.

Nurture refers to the impact of the environment, which involves the process of learning through experiences.

There are two effective ways to study nature-nurture.

• Twin studies: Identical twins have the same genotype, and fraternal twins have an average of 50% of their genes in common.
• Adoption studies: Similarities with the biological family support nature, while similarities with the adoptive family support nurture.

Historical Origins

Developmental psychology as a discipline did not exist until after the industrial revolution when the need for an educated workforce led to the social construction of childhood as a distinct stage in a person’s life.

The notion of childhood originates in the Western world and this is why the early research derives from this location. Initially, developmental psychologists were interested in studying the mind of the child so that education and learning could be more effective.

Developmental changes during adulthood are an even more recent area of study. This is mainly due to advances in medical science, enabling people to live to old age.

Charles Darwin is credited with conducting the first systematic study of developmental psychology. In 1877 he published a short paper detailing the development of innate forms of communication-based on scientific observations of his infant son, Doddy.

However, the emergence of developmental psychology as a specific discipline can be traced back to 1882 when Wilhelm Preyer (a German physiologist) published a book entitled The Mind of the Child .

In the book, Preyer describes the development of his own daughter from birth to two and a half years. Importantly, Preyer used rigorous scientific procedures throughout studying the many abilities of his daughter.

In 1888 Preyer’s publication was translated into English, by which time developmental psychology as a discipline was fully established with a further 47 empirical studies from Europe, North America and Britain also published to facilitate the dissemination of knowledge in the field.

During the 1900s three key figures have dominated the field with their extensive theories of human development, namely Jean Piaget (1896-1980), Lev Vygotsky (1896-1934) and John Bowlby (1907-1990). Indeed, much of the current research continues to be influenced by these three theorists.

Baltes, P. B., Reese, H., & Lipsett, L. (1980) Lifespan developmental psychology, Annual Review of Pyschology 31 : 65 – 110.

Darwin, C. (1877). A Biographical Sketch of an Infant.   Mind , 2, 285-294.

Preyer, W.T. (1882). Die Seele des Kindes: Beobachtungen über die geistige Entwicklung des Menschen in den ersten Lebensjahren .Grieben, Leipzig,

Preyer, W.T. (1888). The soul of the child: observations on the mental development of man in the first years of life .

Rutter, M. (1981). STRESS, COPING AND DEVELOPMENT: SOME ISSUES AND SOME QUESTIONS*. Journal of Child Psychology and Psychiatry, 22(4) , 323-356.

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• Published: 29 July 2021

The evolution of our understanding of human development over the last 10 years

• Ali H. Brivanlou   ORCID: orcid.org/0000-0002-1761-280X 1 &
• Norbert Gleicher   ORCID: orcid.org/0000-0002-0202-4167 2 , 3 , 4  

Nature Communications volume  12 , Article number:  4615 ( 2021 ) Cite this article

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• Developmental biology
• Embryogenesis

As it fulfills an irresistible need to understand our own origins, research on human development occupies a unique niche in scientific and medical research. In this Comment, we explore the progress in our understanding of human development over the past 10 years. The focus is on basic research, clinical applications, and ethical considerations.

What basic research has taught us about human development

Over the last decade, progress in understanding our own development was mostly driven by the emergence and combination of remarkable new technologies. New molecular biology tools such as single-cell RNA-sequencing (sc-RNA-seq) unveiled the earliest genetic signature of the three cell lineages of the human blastocyst and allowed for the discovery of human-specific signatures 1 , 2 , 3 . CRISPR/Cas9 genome editing has offered further access to in vitro functional studies in human blastocysts 4 . However, as we discuss below, an ethical line was crossed when a group claimed that genetically modified human embryos had been transferred, leading to births 5 when neither public opinion nor a consensus within the scientific community had been reached regarding whether crossing the germline in in vitro fertilization (IVF) was safe and ethically acceptable.

On the embryology side, the development of an in vitro attachment platform for human blastocysts offered a first glance into post-implantation events up to 12 days 1 , 3 , 5 , 6 . This paved the way for several important discoveries, including the observation that the human embryo can self-organize to generate embryonic and extraembryonic germ layers, yolk sac, and amniotic cavities in the absence of maternal influences 5 , 6 ; and the presence of a transient embryonic tissue of trophectodermal lineage, adjacent to the yolk sac, therefore named, yolk-sac trophectoderm ( ysTE ) 5 . The presence of these seemingly human-specific populations was independently confirmed by sc-RNA-seq 1 .

The marriage of stem cell biology with bioengineering gave birth to the field of synthetic embryology 7 , 8 , 9 , 10 , 11 , 12 , 13 . This technology uses human embryonic stem cells (hESCs) cultured on geometrically confined micropatterned substrates to generate 2D in vitro models of human conceptuses, such as models of the gastrula ( gastruloids ) 7 , 8 , 9 , 10 , 11 , 12 , 13 , or parts of the embryo, such as cerebroids and neuruloids 14 . Thousands of nearly identical self-organizing human embryonic structures allow for standardization and reproducibility, which cannot be achieved in standard organoid structures 15 . Cells within these structures can be tracked and quantified in real time with sub-cellular resolution, using sophisticated quantification code, including artificial intelligence 14 .

Human gastruloids induce formation of the primitive streak and have enabled the deciphering of the molecular network underlying gastrulation—the most crucial moment of our lives 7 , 8 , 9 , 10 , 11 , 12 , 13 . 3D models of human epiblasts can spontaneously break axial symmetry, thus providing an assay for the elucidation of molecular events underlying the emergence of antero–posterior polarity 11 , 16 . A highly homogenous population of self-organizing 3D models of amniotic ectoderm-like cells can be obtained by combining microfluidic and microculture approaches 17 .

Finally, the development of interspecies chimeras provided the most stringent in vivo validation of human embryo models 9 , 10 , 18 . Unimaginable in human models, inter-species chimeras have become the next best choice to test whether hESC behavior in self-organizing gastruloids , as observed on microchips, would also occur in an embryonic environment 10 , 18 , 19 . Human/bird chimeras generated from transplanting human gastruloids into early chick embryos in ovo unexpectedly proved more efficient than previous methods 9 , 19 . They allowed for the observation of an entire self-organizing embryonic axis in bird eggs 9 . As birds are closer to dinosaurs than to humans, this high rate of success with these chimeras further suggested that these early patterning events must be highly conserved.

Translational clinical applications that arose from basic research

The past 10 years bore witness to significant clinical progress in reproductive medicine, often translated from basic research. Successful human uterus transplantation and the subsequent birth of healthy offspring was, for example, only achieved after years of meticulous laboratory work in animals 10 . Significant improvements in cryopreservation technology for human eggs and ovarian tissue were also preceded by research in model systems 10 , 20 . Practical clinical applications have been developed for women in need of cancer treatment that are toxic to ovaries. In these cases, oocytes and/or ovarian tissue can be cryopreserved for later use in fertility treatments once the patient is cured of her cancer 21 . This ever-evolving technology has already proven to result in live births, and has also become an integral part of routine infertility treatments with IVF, giving rise to the brand-new concept of fertility extension through egg-freezing.

Diagnostic technologies to assess retrieved eggs and preimplantation-stage embryos in the IVF process have been disappointing. For example, tracking extended embryo culture to blastocyst-stage with time-lapse imaging failed to improve embryo selection 22 . That chromosomal-abnormal embryos increase with maternal (but not paternal) age has been interpreted to mean that chromosomal abnormalities were a principal cause for lower implantation chances and higher miscarriage risks among older women. This assumption led to the rapidly growing utilization of chromosomal testing of human embryos prior to embryo transfer in a procedure recently renamed preimplantation genetic testing for aneuploidy (PGT-A) 23 . The hypothesis behind PGT-A is to exclude chromosomal-abnormal embryos from the transfer, thereby improving implantation potentials of remaining euploid embryos.

Here too, clinical evidence was unable to confirm the hypothesis 24 . Moreover, basic research demonstrated a self-correction mechanism in mouse 25 and human embryos 26 , 27 , 28 , 29 that arose during embryogenesis that was cell lineage-specific to the embryonic cell lineage. In contrast, PGT-A biopsies are obtained from the extraembryonic-derived trophectoderm, rendering any diagnostic procedure at the blastocyst stage ineffective. In addition, mathematical modeling demonstrated that results from a single trophectoderm biopsy could not be extrapolated to the whole embryo 30 . Transfer of PGT-A “chromosomal-abnormal diagnosed embryos” has resulted in the births of over 400 chromosomal-normal offspring 20 , 21 .

In recent years, increasing attention has also been given to the quickly evolving understanding of how interdependent lifestyle and human fertility are 31 , 32 , 33 , including the influence of diet on the microbiome, as in many other areas of medicine.

The ethical significance of understanding human development

Whether in clinical medicine or in the research laboratory, human embryology has remained an ethical minefield, strongly influenced by socio-political and religious considerations. At the core of the controversy resides the special moral value of the human embryo, a subject that has come to the forefront again with the ascent of human embryonic stem cell research 34 . There is, however, little consensus as to how to answer a previously raised question: “ what is an embryo ?” 35 . The term pre-embryo, first introduced in 1986, was defined as the interval up to the appearance of the primitive streak, which marks biological individuation at ~14 days post-fertilization. This definition designated the period beyond 14 days as the time when a pre-embryo attains special moral status 36 , 37 . Paradoxically, the term pre-embryo has been replaced by the indiscriminate use of the term embryo, whether at preimplantation cleavage or blastocyst-stages or post-implantation before day 14. It was suggested that the distinction was important for ethical, moral, and biological relevance. The principal reason is simple: Until a pre-embryo becomes an embryo, there is no way of knowing whether implantation has taken place, whether a pregnancy is developing, whether there is a single pregnancy or twinning, or whether fertilization ended up in a benign (hydatidiform mole) or even in a malignant tumor (choriocarcinoma) 35 . Assigning advanced moral value to embryos at those early stages is, therefore, difficult to defend.

The past 10 years have witnessed innumerous ethical debates related to this subject, each with its own social, historical, and religious justifications, reflecting cultural diversities in human populations. Most are triggered by scientific breakthroughs. We summarize here the major ethical challenges preoccupying reproductive research and clinical practice.

We have already briefly referred to CRISPR/Cas9 genome editing. While the use of sc-RNA-seq to identify the molecular blueprint of human development has not elicited significant controversy, CRISPR/Cas9 genome editing of human embryos has been a topic of intense discussions and is currently permissible only in vitro 38 . An alleged attempt in China of implanting human genome-edited embryos into the uterus supposedly led to two births (one a twin birth). Though widely discussed in the media, neither attempt was published in the medical literature, and therefore cannot be verified 5 , 38 .

The ethical debates surrounding the 14-day rule, quiescent since the early IVF days, experienced a rebirth that was prompted by in vitro human embryo attachment studies and the emergence of synthetic human embryos. Within this context, we note that self-organizing embryo models are nothing more than cells in culture and are certainly not embryos. Regardless of scientific merits, in the U.S., the National Institutes of Health (NIH) currently prohibits the use of public funds for the study of synthetic embryos “for ethical reasons”. After being under an NIH moratorium for more than a year, research on chimeras is now, however, again permitted, though human/non-human primate chimeras remain prohibited.

These ongoing ethical debates mostly also mirror those surrounding the lack of U.S. federal funding for clinical IVF and related research, as well as hESCs-derived model embryos. In this context, the American Society for Reproductive Medicine (ASRM)’s Ethics in Embryo Research Task Force recently made an important statement: “ Scientific research using human embryos advances human health and provides vital insights into reproduction and disease ” 39 .

Provided certain guidelines and safeguards are followed, research with already existing embryos or embryos specifically produced for research should be ethically acceptable as a means of obtaining new knowledge that may benefit human health. ASRM also pointed out that scientists and society must understand which research questions necessitate the use of human embryos.

It is gratifying to acknowledge the history and vitality of ongoing debates, especially since they increasingly mimic decision-making processes in the medical field. These debates are meant to be based on cost-benefit and/or risk-benefit assessments. These debates will, unquestionably, continue and, indeed, considering that every intervention has consequences, must be decided based on careful considerations, including all relevant stakeholders and all parts of society.

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Acknowledgements

We like to thank Min Yang, Jean Marx Santel, Adam Souza, and Amir Brivanlou, for data gathering and critical reading of the manuscript, and constructive criticism.

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What is Development?

Human Development or Lifespan Development is the scientific study of the ways in which people change, as well as remain the same, from conception to death. You will discover that the field, known more broadly as developmental science , examines changes and stability across multiple domains of psychological and social functioning. These include physical and neurophysiological processes, cognition, language, emotion, personality, moral, and psychosocial development, including our relationships with others.

Originally concerned with infants and children, the field has expanded to include adolescence and more recently, aging and the entire life span. Previously, the message was once you are 25, your development is essentially completed. Our academic knowledge of the lifespan has changed, and although there is still less research on adulthood than on childhood, adulthood is gaining increasing attention. This is particularly true now that the large cohort known as the “baby boomers” are beginning to enter late adulthood. The assumption that early childhood experiences dictate our future is also being called into question. Instead, we have come to appreciate that growth and change continues throughout life and experience continues to have an impact on who we are and how we relate to others. We now recognize that adulthood is a dynamic period of life marked by continued cognitive, social, and psychological development.

You will also discover that developmental psychologists investigate key questions, such as whether children are qualitatively different from adults or simply lack the experience that adults draw upon. Other issues they consider include the question of whether development occurs through the gradual accumulation of knowledge or through qualitative shifts from one stage of thinking to another, or if children are born with innate knowledge or figure things out through experience, and whether development is driven by the social context or something inside each child. From these questions, you may already be thinking that developmental psychology is related to other applied fields. You are right. Developmental science informs many applied fields, including, educational psychology, developmental psychopathology, and intervention science. It also complements several other basic research fields in psychology including social psychology, cognitive psychology, and cross-cultural psychology. Lastly, it draws from the theories and research of several scientific fields including biology, sociology, health care, nutrition, and anthropology.

Learning Objectives: Lifespan Perspective

• Explain the lifespan perspective and its assumptions about development
• Differentiate periods of human development
• Identify key assumptions and major meta-theories underlying lifespan development 
• Identify major historical and contemporary theories focusing on lifespan development

Lifespan Perspective

Paul Baltes identified several underlying principles of the lifespan perspective (Baltes, 1987; Baltes, Lindenberger, & Staudinger, 2006).

• Development is lifelong . Lifespan theorists believe that development is life-long, and change is apparent across the lifespan. No single age period is more crucial, characterizes, or dominates human development. Consequently, the term lifespan development will be used throughout the textbook.
• Development is multidirectional and multidimensional.  Lifespan researchers hold that different people follow different developmental pathways, and proceed along pathways at different rates. Even within the same person, different dimensions or domains of development can change in different ways.
• Development includes both gains and losses . Lifespan theorists do not agree with the traditional view of development that childhood is a period characterized by developmental gains, whereas old age is a time of loss. Instead, the lifespan approach holds that at every age, we may show gains in some areas of development, while showing losses in other areas. Every change, whether it is finishing high school, getting married, or becoming a parent, entails both growth and loss.
• Development is characterized by plasticity. Plasticity is about malleability , or our potential to change and to follow a wide range of developmental pathways.  For instance, plasticity is illustrated in the brain’s ability to learn from experience and the many ways it can recover from injury.
• Development is embedded in historical and cultural contexts. Lifespan researchers believe that d evelopment is influenced by the many social contexts in which it unfolds. How  people develop will depend on their societal and cultural contexts, and on the historical period during which their development takes place.
•   Development is multiply determined. Lifespan theorists argue that development is caused by multiple factors, and is always shaped by  both biological and environmental factors. In addition, the individual plays an active role in their own development.
• Development is multidisciplinary. As mentioned at the start of the chapter, human development is such a vast topic of study that it requires the theories, research methods, and knowledge bases of many academic disciplines.

Contextualism as paradigm.  Baltes (1987) identified three specific developmental systems of influence, all of which include biological and environmental forces.

• Normative age-graded influences: An age-grade is a specific age group, such as toddler, adolescent, or senior . Humans experience particular age-graded social experiences (e.g., starting school) and biological changes (e.g., puberty).
• Normative history-graded influences: The time period in which you are born (see Table 1.1) shapes your experiences. A cohort is a group of people who are born at roughly the same period in a particular society. These people travel through life often experiencing similar historical changes at similar ages. History-graded influences include both environmental determinants (e.g., historical changes in the job market) and biological determinants (e.g., historical changes in life expectancy).
• Non-normative influences : People’s development is also shaped by specific influences that are not organized by age or historical time, such as immigration, accidents, or the death of a parent. These can be environmental (e.g., parental mental health issues) or biological (e.g., life threatening illness).

Table 1.1. Which generation (cohort) are you?

adapted from Lally & Valentine-French, 2019

Domains of development. We change across three general domains/dimensions; physical, cognitive, and psychosocial. The physical domain includes changes in height and weight, sensory capabilities, the nervous system, as well as the propensity for disease and illness . The cognitive domain encompasses the changes in intelligence, wisdom, perception, problem-solving, memory, and language. The psychosocial domain focuses on changes in emotion, self-perception and interpersonal relationships with families, peers, and friends. All three domains influence each other. It is also important to note that a change in one domain may cascade and prompt changes in the other domains. For instance, an infant who has started to crawl or walk will encounter more objects and people, thus fostering developmental change in the child’s understanding of the physical and social world.

Contextual perspectives , like the lifespan approach, highlight societal contexts that influence our development. An important societal factor is our social standing, socioeconomic status, or social class. Socioeconomic status (SES) is a way to identify families and households based on their shared levels of education, income, and occupation. While there is certainly individual variation, members of a social class tend to share similar privileges, opportunities, lifestyles, patterns of consumption, parenting styles, stressors, religious preferences, and other aspects of daily life. All of us born into a class system are socially located, and we may move up or down depending on a combination of both socially and individually created limits and opportunities.

Families with higher socioeconomic status usually are in occupations (e.g., attorneys, physicians, executives) that not only pay better, but also grant them a certain degree of freedom and control over their job. Having a sense of autonomy or control is a key factor in experiencing job satisfaction, personal happiness, and ultimately health and well-being (Weitz, 2007). Those families with lower socioeconomic status are typically in occupations that are more routine, more heavily supervised, and require less formal education. These occupations are also more subject to job disruptions, including lay-offs and lower wages.

Poverty level is an income amount established by the federal government that is based on a set of thresholds that vary by family size (United States Census Bureau, 2016). If a family’s income is less than the government threshold, that family is considered in poverty. Those living at or near poverty level may find it extremely difficult to sustain a household with this amount of income. Poverty is associated with poorer health and a lower life expectancy due to poorer diet, less healthcare, greater stress, working in more dangerous occupations, higher infant mortality rates, poorer prenatal care, greater iron deficiencies, greater difficulty in school, and many other problems. Members of higher income status may fear losing that status, but the poor may have greater concerns over losing housing.

Today we are more aware of the variations in development and the impact that culture and the environment have on shaping our lives. Culture is the totality of our shared language, knowledge, material objects, and behavior. It includes ideas about what is right and wrong, what to strive for, what to eat, how to speak, what is valued, as well as what kinds of emotions are called for in certain situations. Culture teaches us how to live in a society and allows us to advance because each new generation can benefit from the solutions found and passed down from previous generations. Culture is learned from parents, schools, houses of worship, media, friends and others throughout a lifetime. The kinds of traditions and values that evolve in a particular culture serve to help members function and value their own society. We tend to believe that our own culture’s practices and expectations are the right ones. This belief that our own culture is superior is called ethnocentrism and is a normal by-product of growing up in a culture. It becomes a roadblock, however, when it inhibits understanding of cultural practices from other societies. Cultural relativity is an appreciation for cultural differences and the understanding that cultural practices are best understood from the standpoint of that particular culture.

Culture is an extremely important context for human development and understanding development requires being able to identify which features of development are culturally based. This understanding is somewhat new and still being explored. Much of what developmental theorists have described in the past has been culturally bound and difficult to apply to various cultural contexts. The reader should keep this in mind and realize that there is still much that is unknown when comparing development across cultures.

Lifespan vs. Life expectancy: At this point you must be wondering what the difference between lifespan and life expectancy is, according to developmentalists. Lifespan , or longevity, refers to the maximum age any member of a species can reach under optimal conditions . For instance, the grey wolf can live up to 20 years in captivity, the bald eagle up to 50 years, and the Galapagos tortoise over 150 years (Smithsonian National Zoo, 2016). The longest recorded lifespan for a human was Jean Calment who died in 1994 at the age of 122 years, 5 months, and 14 days (Guinness World Records, 2016). Life expectancy is the average number of years a person born in a particular time period can typically expect to live (Vogt & Johnson, 2016).

Conceptions of Age

How old are you? Chances are you would answer that question based on the number of years since your birth, or what is called your chronological age . Ever felt older than your chronological age? Some days we might “feel” like we are older, especially if we are not feeling well, are tired, or are stressed out. We might notice that a peer seems more emotionally mature than we are, or that they are physically more capable. So years since birth is not the only way we can conceptualize age.

Biological age: Another way developmental researchers can think about the concept of age is to examine how quickly the body is aging , this is your biological age . Several factors determine the rate at which our body ages. Our nutrition, level of physical activity, sleeping habits, smoking, alcohol consumption, how we mentally handle stress, and the genetic history of our ancestors, to name but a few.

Psychological age: Our psychologically adaptive capacity compared to others of our chronological age is our psychological age . This includes our cognitive capacity along with our emotional beliefs about how old we are. An individual who has cognitive impairments might be 20 years of age, yet has the mental capacity of an 8-year-old. A 70- year-old might be travelling to new countries, taking courses at college, or starting a new business. Compared to others of our age group, we may be more or less active and excited to meet new challenges. Remember you are as young or old as you feel.

Social age: Our social age is based on the social norms of our culture and the expectations our culture has for people of our age group . Our culture often reminds us whether we are “on target” or “off target” for reaching certain social milestones, such as completing our education, moving away from home, having children, or retiring from work. However, there have been arguments that social age is becoming less relevant in the 21st century (Neugarten, 1979; 1996). If you look around at your fellow students at college you might notice more people who are older than traditional aged college students, those 18 to 25. Similarly, the age at which people are moving away from the home of their parents, starting their careers, getting married or having children, or even whether they get married or have children at all, is changing.

Those who study lifespan development recognize that chronological age does not completely capture a person’s age. Our age profile is much more complex than this. A person may be physically more competent than others in their age group, while being psychologically immature. So, how old are you?

Table 1.2 Age Periods of Development

Table 1.2 shows the developmental periods that will be explored in this book, starting with prenatal development and continuing thought late adulthood to death. Both childhood and adulthood are divided into multiple developmental periods. So, while both an 8-month old and an 8-year-old are considered children, they have very different motor abilities, social relationships, and cognitive skills. Their nutritional needs are different and their primary psychological concerns are also distinctive. The same is true of an 18-year-old and an 80-year-old, even though both are considered adults.

Prenatal Development : Conception occurs and development begins. All of the major structures of the body are forming, and the health of the mother is of primary concern. Understanding nutrition, teratogens , or environmental factors that can lead to birth defects , and labor and delivery are primary concerns.

Infancy and Toddlerhood : The first two years of life are ones of dramatic growth and change. A newborn, with a keen sense of hearing but very poor vision, is transformed into a walking, talking toddler within a relatively short period of time. Caregivers are also transformed from someone who manages feeding and sleep schedules to a constantly moving guide and safety inspector for a mobile, energetic child.

Early Childhood: This period is also referred to as the preschool years and consists of the years that follow toddlerhood and precede formal schooling. As a two to six-year-old, the child is busy learning language, gaining a sense of self and greater independence, and  beginning to understand the workings of the physical world.

Middle and Late Childhood: The ages of six to the onset of puberty comprise middle and late childhood, and much of what children experience at this age is connected to their involvement in the early grades of school. Now the world becomes one of learning and testing new academic skills, and assessing one’s abilities and accomplishments by making comparisons between self and others.

Adolescence : Adolescence is a period of dramatic physical change marked by an overall growth spurt and sexual maturation, known as puberty . It is also a time of cognitive change as the adolescent begins to think of new possibilities and to consider abstract concepts such as love, fear, and freedom. At the same time, adolescents have a sense of invincibility that puts them at greater risk of accidents or contracting sexually transmitted infections that can have lifelong consequences.

Emerging Adulthood: The period of emerging adulthood is a transitional time between the end of adolescence and before individuals acquire all the benchmarks of adulthood. Continued identity exploration and preparation for full independence from parents are negotiated. Although at one’s physiological peak, emerging adults are most at risk for involvement in violent crimes and substance abuse.

Early Adulthood : The twenties and thirties are identified as early adulthood. Intimate relationships, establishing families (of all shapes and sizes), and work are primary concerns at this stage of life.  For adults with children, developmental changes can become organized around the family life cycle.

Middle Adulthood : The forties through the mid-sixties are referred to as middle adulthood. This is a period in which aging becomes more noticeable and when many people are at their peak of productivity in love and work.  At this age, some people are negotiating adolescent children and aging parents at the same time.

Late Adulthood : Late adulthood is sometimes subdivided into two categories: The young-old who are from 65-84 years and the oldest-old who are 85 years and older. One of the primary differences between these groups is that the young-old are still relatively healthy, productive, active, and the majority continue to live independently. With both age groups the risks of diseases such as arteriosclerosis, cancer, and cerebral vascular disease increase substantially.

Meta-theories of Human Development

The study of development is guided by the assumptions researchers hold about the nature of humans and their development. These assumptions are called meta-theories . “Meta” means “above” or “beyond,” like “meta-physics.” Other terms used to describe meta-theories are “world views,” “cosmologies,” “perspectives,” or “paradigms,” as in “paradigm shifts.” Explicit discussions of meta-theories are found most often in philosophy.

What are meta-theories of human development?

Meta-theories (or world views or paradigms) of human development are sets of assumptions people hold about the nature of humans and the meaning of development — what it looks like, how it happens, what causes it. These assumptions are important because everyone has them, including researchers, but they are often implicit, meaning we are not always consciously aware of them. In the study of development, such assumptions influence everything about how research is conducted: the questions we ask, the measures and methods that are used, and the interpretation of data. For example, if researchers assume that development ends at 18, they do not look for developmental changes after that age. Or, if researchers assume that aging is a process of decline, then they never look for characteristics that might improve as people get older.

All researchers have meta-theories, since assumptions are baked into the theories and methodologies they use. But researchers are often unaware of them, and so these assumptions are rarely acknowledged. It is important to note that meta-theories are not just cold cognitions. They are often deeply held convictions that researchers will fiercely defend. Typically researchers think that their assumptions are self-evident truths. They are often convinced that their assumptions are right and everyone else’s are wrong.

Researchers holding different meta-theories can have difficulty communicating with each other. Since they are asking different questions and using different truth criteria for research, they often argue past each other or misunderstand each other. One group of researchers will offer what they consider to be irrefutable proof of their ideas, which other researchers then dismiss as irrelevant. Discrepancies, inconsistencies, arguments, and furor often characterize an area of study in which researchers from multiple meta-theories are working.

What kinds of assumptions guide the study of human development?

We consider six key assumptions. You may have heard of many of them, since they are perennial issues in the study of development. They include:

• Assumptions about human nature : whether people are born as blank slates ( tabula rasa ) or whether people are inherently good or inherently bad.
• Assumptions about the causes of development : whether development is determined by nature (genes, biology) or determined by nurture (environment, learning).
• Assumptions about the role of the individual in his or her own development: whether people are passive participants, reacting to external forces or whether they are active in choosing and shaping their own development.
• Assumptions about stability vs. change : whether traits, characteristics, and experiences early in life have permanent effects or whether people are malleable and open to change throughout life.
• Assumptions about continuity vs. discontinuity : whether development involves quantitative incremental change or qualitative shifts.
• Assumptions about universality vs. context specificity : whether development follows a universal pathway or depends more on specific experiences and environmental contexts.

Nature of humans. What is the nature of humans? These assumptions refer to beliefs about the underlying qualities of our species– whether humans are born as blank slates ( tabula rasa ) or whether we all bring intrinsic human characteristics with us into the world. For example, these different assumptions are readily apparent in alternative conceptualizations of motivation—some theories assume that motives and motivation are all acquired, whereas others assume that all humans come with intrinsic motivations.

Nature and Nurture: Why are you the way you are? As you consider some of your features (height, weight, personality, being diabetic, etc.), ask yourself whether these features are a result of heredity or environmental factors, or both. Chances are, you can see the ways in which both heredity and environmental factors (such as lifestyle, diet, and so on) have contributed to these features. For decades, scholars have carried on the “nature/nurture” debate. For any particular feature, those on the side of nature would argue that heredity plays the most important role in bringing about that feature. Those on the side of nurture would argue that one’s environment is most significant in shaping the way we are. This debate continues in all aspects of human development, and most scholars agree that there is a constant interplay between the two forces. It is difficult to isolate the root of any single behavior as a result solely of nature or nurture.

Active versus Passive: How much do you play a role in your own developmental path? Are you at the whim of your genetic inheritance or the environment that surrounds you? Some theorists see humans as playing a much more active role in their own development. Piaget, for instance believed that children actively explore their world and construct new ways of thinking to explain the things they experience. In contrast, many behaviorists view humans as being more passive in the developmental process.

Stability versus Change: How similar are you to how you were as a child? Were you always as out-going or reserved as you are now? Some theorists argue that the personality traits of adults are rooted in the behavioral and emotional tendencies of the infant and young child. Others disagree, and believe that these initial tendencies are modified by social and cultural forces over time.

Continuity versus Discontinuity: Is human development best characterized as a slow, gradual process, or is it best viewed as one of more abrupt change? The answer to that question often depends on which developmental theorist you ask and what topic is being studied. The theories of Freud, Erikson, Piaget, and Kohlberg are called stage theories. Stage theories or discontinuous development assume that developmental change occurs in distinct stages that are qualitatively different from each other, and that unfold in a set, universal sequence . At each stage of development, children and adults have different qualities and characteristics. Thus, stage theorists assume development is discontinuous. Others, such as the behaviorists, Vygotsky, and information processing theorists, assume development is a more slow and gradual process known as continuous development . For instance, they would see the adult as not possessing new skills, but as using more advanced skills that were already present in some form in the child. Brain development and environmental experiences contribute to the acquisition of more developed skills.

Universal vs. context specific . A final assumption focuses on whether pathways of development are presumed to be (1) normative and universal, meaning that all people pass through them in the same sequence, or (2) differential and specific, meaning that a variety of different patterns and pathways of developmental change are possible depending on the individual and the context. Some theorists, like Piaget or Erickson, assume that everyone progresses through the same stages of cognitive development in the same order, or that everyone negotiates the same set of developmental tasks at about the same ages. Other theorists, who endorse lifespan or ecological systems approaches, believe that development can take on a wide variety of patterns and pathways, depending on the specific cultural, historical, and societal under which it unfolds.

What are the guiding meta-theories in human development?

These six basic assumptions are clustered into “packages” that go together. Clusters are organized around metaphors, which are at the root of meta-theories of humans and their development. We consider four meta-theories, each with its own metaphor: (1) humans as seeds , as depicted by Maturational meta-theories; (2) humans as machines , as depicted in Mechanistic meta-theories (3) humans as butterflies , as depicted in Organismic meta-theories; and (4) humans as participants in a tennis game, conversation, or dance , as depicted by Contextualist meta-theories. For an overview of these guiding meta-theories, see this chart [pdf] .

• Maturational meta-theory : Maturational meta-theories can be understood using the plant as a metaphor. It is as if humans develop the same way as plants. The important thing to study is people’s “seeds,” that is, their genetic make-up. People are assumed to be passive, the product of their genes. The environment can provide support and nutrition (rain, sun, and soil), but can’t change a person’s nature (poppy seeds will always produce poppies). The role of the person is to be reactive—to their genes. The course of development will be continuous or discontinuous depending on the genetic program, although acorns always grow into oak trees.
• Mechanistic meta-theory : Mechanistic meta-theories can be understood using the machine as a metaphor. It is as if humans change the same way as machines. People are assumed to be made up of pieces that can be studied apart from the rest of them. They are passive, with the energy coming from outside (like gasoline for a car). Development is continuous and people do not develop into something else (a car stays a car). The person can only react to the environment that is controlling them (like a car responding to the gas pedal or the brake). All causes for development come from the outside, from environmental forces.
• Organismic meta-theory : Organismic meta-theories can be understood using the butterfly as a metaphor. It is as if humans develop the same way as butterflies. People are assumed to be made up of structured wholes. Their nature is to be curious, interested, and open to growth. They are active and develop through discontinuous qualitatively different stages (like the caterpillar, chrysalis, and butterfly). People construct their own next steps in development based on the affordances and opportunities provided by the environment. Development is caused by imbalances that lead to structural reorganizations. Development is progressive (gets better) and only goes in one direction (from caterpillar toward butterfly) and not the reverse.
• Contextual meta-theory : Contextual meta-theories can be understood using the tennis game (or dance) as a metaphor. It is as if humans’ development is like a game of tennis or a dance. The important thing to study is the back and forth between the person and his or her context, both of which are assumed to be proactive and acting on their own agendas. Development can be continuous or discontinuous depending on how the game is played. Both person and environment are active partners in the system, which can lead to transformations in both.

What are examples of theories that fall within each meta-theory?

Nested within each higher-order meta-theory are sets of lower-level approaches or theories called “families” of perspectives or theories to denote that they share common properties, based on their similarity to the root metaphors and characteristics of the guiding meta-theories. This table contains several examples of “big” theories of development and provides an analysis of their defining features according to the meta-theoretical assumptions we have been discussing [pdf]. Based on this analysis, we indicate the higher-order family to which we think each big theory or approach belongs.

Although maturational meta-theories were prevalent in the beginning of the 20th century, their popularity has waxed and waned since then, and they have taken on many different forms. These include some formulations of behavioral genetics, sociobiology, evolutionary, ethological, neuroscience, temperament, and personality theories. Maturational assumptions are signaled by concepts such as “trait,” the search for “the aggression gene,” the discovery of the brain system, hormone, or neurotransmitter responsible for a specific condition, or any other terms that suggest development is solely the product of innate or immutable characteristics of individuals. Although they are not typically referred to as “maturational,” there are many kinds of theories that place all the active ingredients of behavior or development inside the head (or more specifically the social cognitions) of the person. Even if they are not direct descendants, these theories can be considered cousins of Maturational meta-theories because they are exclusively focused on the role of the individual.

The prototypic Mechanistic theories are behaviorist, operant, and classical conditioning learning theories, like social learning theory. This family of theories dominated psychology from the early to the mid-20th century, but Mechanistic theories are still alive and well in many areas, such as learning and motivation, and especially in many theories that have been adapted for use in educational systems. New kinds of machines serve as prototypes for mechanistic theories of memory, learning, and automatic functioning—focusing on the computer, the robot, and the automaton. Such assumptions have even pervaded our understanding of biological systems, as seen in metaphors like “the brain is a computer.” And although the “cognitive revolution” was supposed to have overthrown behaviorist assumptions, some cognitivistic theories treat humans as if they were information processing machines.

Perhaps surprisingly, there are also mechanistic assumptions embedded in certain progressive analyses of the effects of societal and social conditions, such as poverty, oppression, racism, and discrimination, which sometimes seem to imply that these external forces are the sole determinants of the development of stereotypes or implicit attitudes. In this case, because all people are presumed to passively internalize these societal prejudices, psychological phenomena are modeled after the metaphor of the “Xerox machine.” Just as in Maturational meta-theories, where humans could be seen as “hosts” to their genes, who were really running the show, in Mechanistic meta-theories, humans can be seen as “hosts” to their own behaviors, which are automatically reflexively produced based on previous social programming.

The prototypical Organismic theory is Piaget’s constructivist theory of cognitive and affective development, and the several neo-constructivist theories that were inspired by Piaget, for example, Kohlberg’s theory of the development of moral reasoning. Other theories living under the Organismic umbrella include Werner’s comparative psychology, focusing on the orthogenetic principle of differentiation and integration, and Erikson, who posited universal age-graded developmental tasks. Other theories that claim kinship with Organismic meta-theories (e.g., theories of intrinsic motivation) do not typically include notions of universal stages or tasks, but focus instead on Organismic assumptions about the nature of humans, specifically, that humans are innately active, curious, and interested, and inherently desire to explore, understand, and fit in with their social and physical environments. With the rise of radical contextualism and cultural relativism in psychology, theories of “universal” anything (e.g., psychological needs, stages, developmental tasks) have come increasingly under attack.

Some of the better-known members of the Contextualist family include Bronfenbrenner’s bio-ecological model and the lifespan approach, both of which arose in reaction to dominant meta-theories of their day (experimental child psychology and Piagetian psychology, respectively), with their almost exclusive focus on the child as a developing individual. The “contextualist” moniker reflects these perspectives’ insistence that development unfolds within and is shaped by higher-order multi-level ecological or contextual forces outside the individual, such as microsystem settings, and societal, cultural, and historical contexts.

Does the field of psychology have meta-theories?

During different historical periods, specific meta-theories dominated the field of psychology. For example, during the 1940s and 1950s, behaviorism held sway. In the 1960s, Piaget’s theories were introduced to the United States and captured the field’s attention. Some fierce theoretical and empirical battles were fought between behaviorists and Piagetians.

When a specific meta-theory governs the field, it becomes very difficult for researchers from opposing meta-theories to work—they have trouble getting funding, they have trouble getting their research findings published, and they are marginalized by other researchers. For example, when the area of motivation was dominated by behaviorists (who believed that all behavior was motivated by rewards and punishments), it was very difficult for researchers to study and publish research on intrinsic motivation.

What is the dominant meta-theory in the field today?

“Cognitivism” is a guiding meta-theory in the field of psychology today. “Cognitivism” is the assumption that all the causal factors that shape human behavior and development are inside the mind or belief system of the person. You can hear the assumptions in the theories of the field: self-efficacy, self-esteem, attributions, perceived social support, values, sense of purpose, goal orientations, internal working model, identity, and so on.

The paradigm that is currently taking over the field of psychology is neuroscience . That is, the brain is in charge of behavior, and neurobiology is destiny. Some branches of neuroscience are predominantly Maturational , as seen in discussions of the brain systems responsible for certain actions, predilections, and characteristics. Other branches are more Contextual , for example, research on neuroplasticity, which examines the way that social contexts and interactions shape the developing brain.

News flash : In the field of psychology outside developmental, most researchers assume that people don’t develop. In personality, social, cognitive, and industrial-organizational psychology, researchers largely examine individual differences as indicators of people’s permanent characteristics.

Who else has meta-theories?

Everyone has meta-theories about human nature and development: parents, teachers, nurses, social workers, doctors, business people, artists, politicians, and so on.

For example,

• doctors assume that weight loss is all about diet and exercise (nurture), so no one can do research on physiological differences in metabolism (nature).
• teachers have assumptions about whether students come with motivation (nature) or have to be motivated from the outside (nurture), and organize their classrooms accordingly.
• parents often argue about the nature of children’s development, whether it’s just the child’s personality (maturational), or the child is going through a normal stage (organismic), or if they are rewarding the wrong behavior (mechanistic).

What is the meta-theory that guides our class and this book?

Our class endorses a life-span perspective on human development, a contextualist perspective that fought its way through the dominant perspectives in child psychology (e.g., development ends at age 18), starting in the 1980s to become one of the dominant meta-theories governing the field of developmental science today. Note that your instructors chose your book, so their meta-theory is influencing the meta-theoretical filter through which you are learning about development.

What is the correct meta-theory?

There is no single correct definition of development or meta-theory. Really. Even the lifespan approach has its drawbacks.

However, as research accumulates, many theories derived from certain meta-theories have been found to be incomplete—so far researchers have not found any significant aspect of development that is caused only by nature or only by nurture. Therefore, most researchers currently say they favor interactionist metatheories, like contextualist or systems meta-theories. However, it is important to look carefully at researchers’ actual work, because sometimes they say that they have one meta-theory, but their work seems to be guided by assumptions from a different meta-theory.

Do I have a meta-theory about development?

Yes, you do. And you can figure out what it is. Although it’s not easy, you can discern your own assumptions about development—by thinking about which assumptions make the most sense to you. You can also see which kinds of theories you prefer and what kinds of recommendations you would make about how to structure development, like how people should parent, teach, or make policies. The hardest part about discovering your own meta-theory is realizing that it is made up of assumptions you have (based on your experiences and messages from society)—that aren’t necessarily true. Our meta-theories sure seem true to each of us!

How do I get rid of my meta-theory?

It’s not really possible to get rid of all of our assumptions. It is our goal to be aware of our own assumptions or meta-theories, to realize that they are not the truth but are our current working models of how the world operates and people develop. The most important thing is to be explicit about our assumptions and to be cognizant of how they are guiding our actions. It is a goal of this class to help students figure out their own assumptions and to help them become (or remain) open to alternative viewpoints.

Adapted from : Ellen Skinner, Glen Richardson, Jennifer Pitzer, and Cynthia Taylor. Portland State University. July 2011.

Historical Theories of Development

Preformationist View : Well into the 18th century, children were merely thought of as little adults. Preformationism , or the belief that a tiny, fully formed human is implanted in the sperm or egg at conception and then grows in size until birth, was the predominant early theory. Children were believed to possess all their sensory capabilities, emotions, and mental aptitude at birth, and as they developed these abilities unfolded on a predetermined schedule (Thomas, 1979). The environment was thought to play no role in determining development .

John Locke (1632-1704): Locke, a British philosopher, refuted the idea of innate knowledge and instead proposed that children are largely shaped by their social environments, especially their education as adults teach them important knowledge. He believed that through education a child learns socialization, or what is needed to be an appropriate member of society. Locke advocated thinking of a child’s mind as a tabula rasa or blank slate , and whatever comes into the child’s mind comes from the environment. Locke emphasized that the environment is especially powerful in the child’s early life because he considered the mind the most pliable then. Locke indicated that the environment exerts its effects through associations between thoughts and feelings, behavioral repetition, imitation, and rewards and punishments (Crain, 2005). Locke’s ideas laid the groundwork for the behavioral perspective and subsequent learning theories of Pavlov, Skinner and Bandura.

Jean-Jacques Rousseau (1712-1778): Like Locke, Rousseau also believed that children were not just little adults. However, he did not believe they were blank slates, but instead developed according to a natural plan which unfolded in different stages (Crain, 2005). He did not believe in teaching them the correct way to think, but believed children should be allowed to think by themselves according to their own ways and an inner, biological timetable. This focus on biological maturation resulted in Rousseau being considered the father of developmental psychology. Followers of Rousseau’s developmental perspective include Gesell, Montessori, and Piaget.

Arnold Gesell (1880-1961): Gesell spent 50 years at the Yale Clinic of Child Development, and with his colleagues he studied the neuromotor development of children. Gesell believed that the child’s development was activated by genes and he called this process maturation (Crain, 2005). Further, he believed that development unfolded in fixed sequences, and he opposed efforts to teach children ahead of schedule as he believed they will engage in behaviors when their nervous systems had sufficiently matured.

Sigmund Freud (1856-1939): Freud was a very influential figure in the area of development. Freud emphasized the importance of early childhood experiences in shaping our personality and behavior. In our natural state, we are biological beings and are driven primarily by instincts. During childhood, however, we begin to become social beings as we learn how to manage our instincts and transform them into socially acceptable behaviors. His assumptions were that personality formed during the first few years of life. The ways in which parents or other caregivers interacted with children were assumed to have a long-lasting impact on children’s emotional states. His beliefs formed the psychodynamic perspective and his theories of psychosexual development and psychopathology dominated the field of psychiatry until the growth of behaviorism in the 1950s.

However, Freud’s theory has been heavily criticized for several reasons. One is that it is very difficult to test scientifically (Crews, 1998). Freud suggested that much of what determines our actions were unknown to us, and as scientists we cannot measure these unconscious concepts. A second criticism is that Freud’s case studies were not validated and cannot be used as evidence for his theories. Many later theories, particularly behaviorism and humanism, came about as challenges to Freud’s views.

Contemporary Theories on Development

Erikson (1902-1994) and Psychosocial Theory: Now, let’s turn to a less controversial psychodynamic theorist, Erik Erikson. Erikson presents eight developmental stages that encompass the entire lifespan. For that reason, Erikson’s psychosocial theory forms the foundation for much of our discussion of psychosocial development.

Erikson (1950) proposed a model of lifespan development that provides a useful guideline for thinking about the changes we experience throughout life. Erikson broke with Freud’s emphasis on sexuality as the cornerstone of social-emotional development and instead suggested that social relationships fostered development. Erikson proposed that each period of life has a unique challenge or crisis that the person who reaches it must face, referred to as psychosocial crises . According to Erikson, successful development involves dealing with and resolving the goals and demands of each of these psychosocial crises in a positive way. These crises are usually called stages, although that is not the term Erikson used. If a person does not resolve a stage successfully, it may hinder their ability to deal with later stages. For example, the person who does not develop a sense of trust (Erikson’s first stage) may find it challenging as an adult to form a positive intimate relationship (Erikson’s sixth stage). Or an individual who does not develop a clear sense of purpose and identity (Erikson’s fifth stage) may become self-absorbed and stagnate rather than work toward the betterment of others (Erikson’s seventh stage).

However, most individuals are able to successfully complete the eight stages of his theory (See Table 1.3).

Table 1.3 Erikson's Psychosocial Stages

Erikson’s theory has been criticized for focusing so heavily on crises and assuming that the completion of one crisis is a prerequisite for the next crisis of development. His theory also focused on the social expectations that are found in certain cultures, but not in all. For instance, the idea that adolescence is a time of searching for identity might translate well in the middle-class culture of the United States, but not as well in cultures where the transition into adulthood coincides with puberty through rites of passage and where adult roles offer fewer choices.

Learning Theory: Also known as Behaviorism , is based on the premise that it is not possible to objectively study the mind, and therefore psychologists should limit their attention to the study of behavior itself. The most famous behaviorist was Burrhus Frederick (B. F.) Skinner (1904–1990), who expanded the principles of behaviorism and also brought them to the attention of the public at large. Skinner used the ideas of stimulus and response, along with the application of rewards or reinforcements, to train pigeons and other animals. In addition, he used the general principles of behaviorism to develop theories about how best to teach children and how to create societies that were peaceful and productive (Skinner, 1957, 1968, 1972).

The behaviorists made substantial contributions to psychology by identifying the principles of learning. Although the behaviorists were incorrect in their beliefs that it was not possible to measure thoughts and feelings, their ideas provided new insights that helped further our understanding regarding the nature-nurture debate as well as the question of free will. The ideas of behaviorism are fundamental to psychology and have been developed to help us better understand the role of prior experiences in a variety of areas of psychology.

Social Learning Theory , or learning by watching others , was developed by Albert Bandura (1977). His theory calls our attention to the ways in which many of our actions are not learned through conditioning, as suggested by Skinner . Young children frequently learn behaviors through imitation. Especially when children do not know what else to do, they learn by modeling or copying the behavior of others.

Bandura (1986) suggests that there is interplay between the environment and the individual. We are not just the product of our surroundings, rather we influence our surroundings. There is interplay between our personality and the way we interpret events and how they influence us. This concept is called reciprocal determinism . An example of this might be the interplay between parents and children. Parents not only influence their child’s environment, perhaps intentionally through the use of reinforcement, etc., but children influence parents as well. Parents may respond differently with their first child than with their fourth. Perhaps they try to be the perfect parents with their firstborn, but by the time their last child comes along they have very different expectations, both of themselves and their child. Our environment creates us and we create our environment.

Other social influences: TV or not TV? Bandura, Ross and Ross (1963) began a series of studies to look at the impact of television on the behavior of children. Bandura began by conducting an experiment in which he showed children a film of a woman hitting an inflatable clown or “bobo” doll. Then the children were allowed in the room, where they found the doll and during their play they began to hit it. The children also demonstrated novel ways of being aggressive toward the doll that were not demonstrated by those children who did not see the aggressive model. Bandura’s research raised concerns about the impact of violence on young children. Since then, considerable research has been conducted on the impact of violent media on children’s aggression including playing video games.

Cognitive Theory: The cognitive theories focus on how our mental processes or cognitions change over time . Three important theories are Jean Piaget’s, Lev Vygotsky’s, and Information-processing.

Jean Piaget (1896-1980) was one of the most influential cognitive theorists in development. He was inspired to explore children’s ability to think and reason by watching his own children’s development. He was one of the first to recognize and map out the ways in which children’s intelligence differs from that of adults (Piaget, 1929). He became interested in this area when he was asked to test the IQ of children and began to notice that there was a pattern in their wrong answers. He believed that children’s intellectual skills change over time and that maturation, rather than training, brings about that change. Children of differing ages interpret the world differently. Piaget theorized that children progressed through four stages of cognitive development (see Table 1.4).

Table 1.4 Piaget's Stages of Cognitive Development

Piaget has been criticized for overemphasizing the role that physical maturation plays in cognitive development and in underestimating the role that culture and experience plays. Looking across cultures reveals considerable variation in what children are able to do at various ages. Research has shown considerable overlap among the four stages and that development is more continuous.

Lev Vygotsky (1896-1934) was a Russian psychologist who wrote in the early 1900s, but whose work was not discovered by researchers in the United States until the 1960s and became more widely known in the 1980s (Crain, 2005). His sociocultural theory emphasizes the importance of culture and interaction in the development of cognitive abilities . Vygotsky differed with Piaget in that he believed that a person not only has a set of abilities, but also a set of potential abilities that can be realized if given the proper guidance from others. Vygotsky developed theories on teaching that have been adopted by educators today.

Information Processing is not the work of a single theorist, but based on the ideas and research of several cognitive scientists studying how individuals perceive, analyze, manipulate, use, and remember information . This approach assumes that humans gradually improve in their processing skills; that is, cognitive development is continuous rather than stage-like. The more complex mental skills of adults are built from the primitive abilities of children. We are born with the ability to notice stimuli, store, and retrieve information. Brain maturation enables advancements in our information processing system. At the same time, interactions with the environment also aid in our development of more effective strategies for processing information.

Urie Bronfenbrenner (1917-2005) developed the Ecological Systems Theory , which provides a framework for understanding and studying the many influences on human development (Bronfenbrenner, 1979). Bronfenbrenner recognized that human interaction is influenced by larger social forces and that an understanding of these forces is essential for understanding an individual. The individual is impacted by several systems including:

• Microsystem includes the individual’s setting and those who have direct, significant contact with the person, such as parents or siblings . The input of those is modified by the cognitive and biological state of the individual as well. These influence the person’s actions, which in turn influence systems operating on him or her.
• Mesosystem includes the larger organizational structures, such as school, the family, or religion. These institutions impact the microsystems just described. The philosophy of the school system, daily routine, assessment methods, and other characteristics can affect the child’s self-image, growth, sense of accomplishment, and schedule thereby impacting the child, physically, cognitively, and emotionally.
• Exosystem includes the larger contexts of community . A community’s values, history, and economy can impact the organizational structures it houses. Mesosystems both influence and are influenced by the exosystem.
• Macrosystem includes the cultural elements, such as global economic conditions, war, technological trends, values, philosophies, and a society’s responses to the global community.
• Chronosystem is the historical context in which these experiences occur. This relates to the different generational time periods previously discussed, such as the baby boomers and millennials.

In sum, a child’s experiences are shaped by larger forces, such as the family, schools, religion, culture, and time period. Bronfenbrenner’s model helps us understand all of the different environments that impact each one of us simultaneously. Despite its comprehensiveness, Bronfenbrenner’s ecological system’s theory is not easy to use. Taking into consideration all the different influences makes it difficult to research and determine the impact of all the different variables (Dixon, 2003). Consequently, psychologists have not fully adopted this approach, although they recognize the importance of the ecology of the individual. Figure 1.9 is a model of Bronfenbrenner’s Ecological Systems Theory.

Figure 1.9. Bronfenbrenner’s Ecological Systems Theory

Supplemental Materials

• This article discusses the importance of critical reflection on the underlying assumptions of developmental psychology as a science.

Teo, T. (1997). Developmental Psychology and the Relevance of a Critical Metatheoretical Reflection. Human Development, 40 (4), 195–210. https://doi.org/10.1159/000278723

Baltes, P. B. (1987). Theoretical propositions of life span developmental psychology: On the dynamics between growth and decline. Developmental Psychology, 23, 611-626.

Baltes, P. B., Lindenberger, U., & Staudinger, U. M. (2006). Life span theory in developmental psychology. In W. Damon, & R. M. Lerner (Eds.), Handbook of child psychology , 6th edition (pp. 569-664). Hoboken, NJ: John Wiley & Sons.

Bandura, A. (1977). Social learning theory . New York: General Learning Press.

Bandura, A. (1986). Social foundations of thought and action: A social-cognitive theory . Upper Saddle River, NJ: Prentice Hall.

Bandura, A, Ross, D. &. Ross S. (1963). Imitation of film-mediated aggressive models. Journal of Abnormal and Social Psychology, 66 , 3-11.

Bronfenbrenner, U. (1979). The ecology of human development: Experiments by nature and design . Cambridge, MA: Harvard University Press.

Crain, W. (2005). Theories of development concepts and applications (5th ed.). New Jersey: Pearson.

Crews, F. C. (1998). Unauthorized Freud: Doubters confront a legend . New York, NY: Viking Press.

Dixon, W. E. (2003). Twenty studies that revolutionized child psy chology. Upper Saddle River, NJ: Prentice Hall.

Erikson, E. H. (1950). Childhood and society . New York: Norton.

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Neugarten, B. L. (1979). Policy for the 1980s: Age or need entitlement? In J. P. Hubbard (Ed.), Aging: Agenda for the eighties, a national journal issues book (pp. 48-52). Washington, DC: Government Research Corporation.

Neugarten, D. A. (Ed.) (1996). The meanings of age . Chicago, IL: The University of Chicago Press.

Piaget, J. (1929). The child’s conception of the world . NY: Harcourt, Brace Jovanovich.

Smithsonian National Zoo. (2016). Retrieved from http://nationalzoo.si.edu/

Skinner, B. (1957). Verbal behavior . Acton, MA: Copley.

Skinner, B. (1968). The technology of teaching . New York, NY: Appleton-Century-Crofts.

Skinner, B. (1972). Beyond freedom and dignity . New York, NY: Vintage Books.

Thomas, R. M. (1979). Comparing theories of child development . Santa Barbara, CA: Wadsworth.

United States Census Bureau. (2016). Povert y. Retrieved from http://www.census.gov/topics/income-poverty/poverty/about/glossary.html

Vogt, W.P., & Johnson, R.B. (2016). The SAGE dictionary of statistics and methodology . Los Angeles, CA: Sage

Webb, S. J., Dawson, G., Bernier, R., & Panagiotides, H. (2006). ERP evidence of atypical face processing in young children with autism. Journal of Autism and Developmental Disorders, 36 , 884-890. doi: 10.1007/s10803-006-0126-x

Weitz, R. (2007). The sociology of health, illness, and health care: A critical approach, (4th ed.). Belmont, CA: Thomson.

OER Attribution: “Lifespan Development: A Psychological Perspective, Second Edition” by Martha Lally and Suzanne Valentine-French is licensed under a CC-BY-NC-SA-3.0

Additional written material (Meta-theories of Human Development) by Ellen Skinner, Glen Richardson, Jennifer Pitzer, and Cynthia Taylor, Portland State University is licensed under a CC BY-NC-SA 4.0 .

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19.1 Erikson’s Theory of Psychosocial Development

Learning objectives.

• Use Erikson’s theory to characterize psychosocial development across the lifespan

Erik Erikson formulated a theory of psychosocial development that posited that development is organized around eight age-graded developmental tasks. At each age, infants, children, adolescents, and adults, negotiate target developmental tasks that are specific to that period of development. When the target task is negotiated successfully, it creates a foundation for future healthy development and provides a basis for the successful negotiation of future developmental tasks. When a task is not well resolved, this makes continued healthy development more difficult. The development of a healthy personality and a sense of competence depend on the successful completion of each task.

Erikson believed that we are aware of what motivates us throughout life. We make conscious choices in life, and these choices focus on meeti ng certain social and cultural needs rather than purely biological ones. Humans are motivated, for instance, by the need to feel that the world is a trustworthy place, that we are capable individuals, that we can make a contribution to society, and that we have lived a meaningful life. These are all psychosocial problems.

Erikson  described eight stages, each with  a major psychosocial task to accomplish or crisis to overcome. Erikson believed that our personality continues to take shape throughout our life span as we face these challenges.  Here is an overview of each stage:

Table 19.1: Erikson’s Psychosocial Stages of Development

Infancy: trust vs. mistrust.

The developmental task of infancy is trust vs. mistrust, and it is negotiated in the establishment of a secure attachment relationship with the caregiver. Erikson maintained that during the first year to year and a half of life the most important goal is the development of a basic sense of trust in one’s caregivers (Erikson, 1982). Infants are dependent and must rely on others to meet their basic physical and psychological needs. A caregiver who consistently meets these needs instills a sense of trust or the belief that the world is a trustworthy place. Caregivers should not worry about overly indulging an infant’s need for comfort, contact, or stimulation. Caregiver responsiveness communicates to infants that their needs will be taken care of, and so is essential in supporting the development of a sense of trust.

Problems establishing trust

Erikson (1982) believed that basic mistrust could interfere with many aspects of psychosocial development and make it more difficult to build love and fellowship with others. Consider the implications for establishing trust if a caregiver is unavailable or is upset and ill-prepared to care for a child. Or if a child is born prematurely, is unwanted, or has physical problems that make him or her less attractive to a parent. Under these circumstances, we cannot assume that the parent is going to care for the child in ways that support the development of trust. As you will read later, it is possible to rework mental models of insecure early relationships, but close and caring relationships with primary caregivers make it much easier for infants to negotiate this first developmental task.

Toddlerhood: Autonomy vs. Shame and Doubt

As the child begins to walk and talk, an interest in independence or autonomy replaces a concern for trust. If infants have built a secure attachment with caregivers, they can use that secure base to explore the world and establish themselves as independent persons, with their own goals and interests. It is the job of the toddler to exert his or her will, and to test the limits of what can be touched, said, and explored. Erikson (1982) believed that toddlers should be encouraged to explore their environments as freely as safety allows, and in so doing develop a sense of independence that will later grow to support self-esteem, initiative, and confidence. If a caregiver is overly anxious about the toddler’s actions for fear that the child will get hurt or is overly critical and controlling about the mistakes they make, the child will get the message that he or she should be ashamed of who they are and instill a sense of doubt in their capacities. Parenting advice based on these ideas would be to keep toddlers safe but to validate their desires for exploration and independence, and to encourage them to learn by doing.

Early Childhood: Initiative vs. Guilt

The trust and autonomy of previous stages develop into a desire to take initiative or to think of ideas and initiate action (Erikson, 1982). Once children reach the preschool stage (ages 3–6 years), they are capable of initiating activities and asserting control over their world through social interactions and play. By learning to plan and achieve goals while interacting with others, preschool children can master this task. Children may want to build a fort with the cushions from the living room couch or open a lemonade stand in the driveway or make a zoo with their stuffed animals and issue tickets to those who want to come. Or they may just want to get themselves ready for bed without any assistance. Initiative, a sense of ambition and responsibility, occurs when parents allow a child to explore within limits and then support the child’s choice. To reinforce taking initiative, caregivers should offer praise for the child’s efforts and avoid being critical of messes or mistakes. Placing pictures of drawings on the refrigerator, purchasing mud pies for dinner, and admiring towers of legos will facilitate the child’s sense of initiative. These children will develop self-confidence and feel a sense of purpose. Those who are unsuccessful at this stage—with their initiative misfiring or stifled by over-controlling parents—may develop feelings of inadequacy and guilt.

Middle Childhood: Industry vs. Inferiority

According to Erikson, children in middle and late childhood are very busy or industrious (Erikson, 1982). They are constantly doing, planning, playing, getting together with friends, and achieving. This is a very active time, and a time when they are gaining a sense of how they measure up when compared with peers. Erikson believed that if these industrious children can be successful in their endeavors, they will get a sense of confidence for future challenges. If instead, a child feels that they are not measuring up to their peers, feelings of inferiority and self-doubt will develop. These feelings of inferiority can, according to Erikson, lead to an inferiority complex that lasts into adulthood. To help children successfully negotiate this stage, they should be encouraged to explore their abilities. They should be given authentic feedback as well. Failure is not necessarily a horrible thing according to Erikson. Indeed, failure is a type of feedback which may help a child form a sense of modesty. A balance of competence and modesty is ideal for creating a sense of competence in the child.

This video illustrates Erikson’s stage of Industry. It features a 9-year old girl in Minneapolis who makes and sells bracelets with the proceeds going to support building black businesses and those in need because of COVID-19.

Download the transcript for this video

Adolescence: Identity vs. Role Confusion

Erikson believed that the primary psychosocial task of adolescence was establishing an  identity . As formal operational thinking unfolds, bringing with it adolescent self-consciousness and the ability to reflect on one’s own attributes and behaviors, teens often struggle with the question “Who am I?” This includes questions regarding their appearance, vocational choices and career aspirations, education, relationships, sexuality, political and social views, personality, and interests. Erikson saw this as a period of uncertainty, confusion, exploration, experimentation, and learning regarding identity and one’s life path. Erikson suggested that most adolescents experience  psychological moratorium ,  where teens put on hold commitment to an identity while exploring their options . The culmination of this exploration is a more coherent view of oneself. Those who are unsuccessful at resolving this stage may either withdraw further into social isolation or become lost in the crowd. However, more recent research, suggests that few leave the adolescent period with identity achievement, and that for most of us the process of identity formation continues all during the years of emerging and young adulthood (Côtè, 2006).

Early Adulthood: Intimacy vs. Isolation

Erikson’s (1950, 1968) sixth stage of psychosocial development focuses on establishing intimate relationships or risking social isolation. Intimate relationships are more difficult if one is still struggling with identity. Achieving a sense of identity is a life-long process, as there are periods of identity crisis and stability. Once a sense of identity is established, young adults’ focus often turns to intimate relationships. The word “intimacy” is often used to describe romantic or sexual relationships, but it also refers to the closeness, caring, and personal disclosure that can be found in many other types of relationships as well– and, of course, it is possible to have sexual relationships that do not include psychological intimacy or closeness. The need for intimacy can be met in many ways, including with friendships, familial relationships, and romantic relationships.

Middle Adulthood: Generativity vs. Stagnation

According to Erikson (1950, 1982)  generativity  encompasses procreativity, productivity, creativity, and legacy.  This stage includes the generation of new beings, new ideas or creations, and lasting contributions, as well as self-generation concerned with further identity development. Erikson believed that the stage of generativity, which lasts from the 40s to the 60s, during which one established a family and career, was the longest of all the stages. Individuals at midlife are primarily concerned with leaving a positive  legacy  of themselves, and parenthood is the primary generative type. Erikson understood that work and family relationships may be in conflict due to the obligations and responsibilities of each, but he believed it was overall a positive developmental time. In addition to being parents and working, Erikson also described individuals as being involved in the community during this stage, for example, providing mentoring, coaching, community service, or taking leadership in church or other community organizations. A sense of stagnation occurs when one is not active in generative matters, however, stagnation can motive a person to redirect energies into more meaningful activities.

Erikson identified “virtues” for each of his eight stages, and the virtue emerging when one achieves generativity is “care”. Erikson believed that those in middle adulthood should “take care of the persons, the products, and the ideas one has learned to care for” (Erikson, 1982, p. 67). Further, Erikson believed that the strengths gained from the six earlier stages are essential for the generational task of cultivating strength in the next generation. Erikson further argued that generativity occurred best after the individual had resolved issues of identity and intimacy (Peterson & Duncan, 2007).

Research has demonstrated that generative adults possess many positive characteristics, including good cultural knowledge and healthy adaptation to the world (Peterson & Duncan, 2007). Using the Big 5 personality traits, generative women and men scored high on conscientiousness, extraversion, agreeableness, openness to experience, and low on neuroticism (de St. Aubin & McAdams, 1995; Peterson, Smirles, & Wentworth, 1997). Additionally, women scoring higher on generativity at age 52, were rated higher in positive personality characteristics, reported higher satisfaction with marriage and motherhood, and showed more successful aging at age 62 (Peterson & Duncan, 2007). Similarly, men rated higher on generativity at midlife also showed stronger global cognitive functioning (e.g., memory, attention, calculation), stronger executive functioning (e.g., response inhibition, abstract thinking, cognitive flexibility), and lower levels of depression in late adulthood (Malone, Liu, Vaillant, Rentz, & Waldinger, 2016).

Erikson (1982) indicated that at the end of this demanding stage, individuals may withdraw as generativity is no longer expected in late adulthood. This releases elders from the task of caretaking or working. However, not feeling needed or challenged may result in stagnation, and consequently one should not fully withdraw from generative tasks as they enter Erikson’s last stage in late adulthood. People in late adulthood continue to be productive in many ways. These include work, education, volunteering, family life, and intimate relationships. Older adults also experience generativity through voting, forming and helping social institutions like community centers, churches and schools. Thinking of the issue of legacy , psychoanalyst Erik Erikson wrote “I am what survives me” (Havey, 2015).

Late Adulthood: Integrity vs. Despair

In terms of psychosocial development, the tasks of adulthood were about becoming the self that you want to become (i.e., Identity) and creating the life you want to live, including establishing or maintaining the close interpersonal relationships that will be crucial to your physical and psychological health and well -being (i.e., Intimacy). The value of that life project is negotiated during middle adulthood in the search for meaning and a purpose larger than yourself that will contribute to your legacy (i.e., generativity). So in old age, this final task basically comes down to whether you have built a life and constructed a self that is sufficient to withstand the disintegration of your physical body, the death of many of those you love, and eventually and inevitably, strong enough to face your own impending death with dignity and grace.

Like all psychosocial tasks, this one has two potential resolutions:  Integrity , or  a   sense of self-acceptance, contentment with life and imminent death versus d espair , or  a lack of fulfillment or peace and the inability to come to terms with life, aging, and approaching death . Development during elderhood, as during all developmental periods, is a bio-psycho-social process that takes place in specific societal and historical contexts. But this task, at the end of life, offers offers us the prospect of lifting off of those geographical, societal, and temporal limitations. We have the potential to  transcend  them, to establish a sense of wholeness and acceptance by getting in touch with our universal connection to humanity, past, present, and future. Like birth, death is a journey that every single one of us will take.

Erikson’s Ninth Stage of Psychosocial Development

Erikson collaborated with his wife, Joan, throughout much of his work on psychosocial development. In the Eriksons’ older years, they re-examined the eight stages and generated additional ideas about how development evolves during a person’s 80s and 90s. After Erik Erikson passed away in 1994, Joan published a chapter on the  ninth stage of development , in which she proposed (from her own experiences and Erikson’s notes) that  older adults revisit the previous eight stages and deal with the previous conflicts in new ways, as they cope with the physical and social changes of growing old . In the first eight stages, all of the conflicts are presented in a syntonic-dystonic matter, meaning that the first term listed in the conflict is the positive, sought-after achievement and the second term is the less-desirable goal (i.e., trust is more desirable than mistrust and integrity is more desirable than despair) (Perry et al., 2015).

During the ninth stage, the Erikson’s argue that the dystonic, or less desirable outcome, come to take precedence again. For example, an older adult may become mistrustful (trust vs. mistrust), feel more guilt about not having the abilities to do what they once did (initiative vs. guilt), feel less competent compared with others (industry vs. inferiority), lose a sense of identity as they become dependent on others (identity vs. role confusion), become increasingly isolated (intimacy vs. isolation), and feel that they have less to offer society (generativity vs. stagnation) (Gusky, 2012). The Eriksons found that those who successfully come to terms with these changes and adjustments in later life make headway towards  gerotranscendence,  a term coined by gerontologist Lars Tornstam to represent a  greater awareness of one’s own life and connection to the universe, increased ties to the past, and a positive, transcendent, perspective about life.

Strengths and Weaknesses of Erikson’s Theory

Erikson’s eight stages form a foundation for discussions on emotional and social development during the lifespan. Keep in mind, however, that these stages or crises can occur more than once or at different times of life. For instance, a person may struggle with a lack of trust beyond infancy. Erikson’s theory has been criticized for focusing so heavily on stages and assuming that the completion of one stage is a prerequisite for the next crisis of development. His theory also focuses on the social expectations that are found in certain cultures, but not in all. For instance, the idea that adolescence is a time of searching for identity might translate well in the middle-class culture of the United States, but not as well in cultures where the transition into adulthood coincides with puberty through rites of passage and where adult roles offer fewer choices.

By and large, Erikson’s view that development continues throughout the lifespan is very significant and has received great recognition. However, it has been criticized for focusing on more men than women and also for its vagueness, making it difficult to test rigorously.

Watch this video to learn more about each of Erikson’s stages.

You can view the transcript for “Erikson’s psychosocial development | Individuals and Society | MCAT | Khan Academy” here (opens in new window) .

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• “Lifespan Development: A Psychological Perspective, Second Edition” by Martha Lally and Suzanne Valentine-French is licensed under a CC-BY-NC-SA-3.0
• Lifespan Development by Lumen Learning is licensed under a Creative Commons Attribution 4.0 International License
• Psychosocial Development by Lumen Learning  is licensed under a Creative Commons Attribution 4.0 International License
• Child Growth and Development  by  College of the Canyons , Jennifer Paris, Antoinette Ricardo, and Dawn Rymond and is used under a  CC BY 4.0 international license
• “Play and Peers” by Dan Grimes & Brandy Brennan, Portland State University, and is licensed CC-BY-NC-SA-4.0
• “Identity Development During Adolescence” by Dan Grimes & Brandy Brennan, Portland State University and are licensed under a CC-BY-NC-SA-4.0
• Love, Friendship, and Social Support  by  Debi Brannan and Cynthia D. Mohr  is licensed under a  Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License .
• “Love and Relationships” by Ellen Skinner & Heather Brule, Portland State University is licensed under CC BY-NC-SA 4.0
• Creativity by Ellen Skinner & Dan Grimes, Portland State University is licensed under a  CC-BY-NC-SA-4.0
• Psyc 200 Lifespan Psychology.  Authored by : Laura Overstreet.  Located at :  http://opencourselibrary.org/econ-201/ .  License :  CC BY: Attribution
• Psychodynamic and Psychosocial Theories of Early Childhood . Authored by : Stephanie Loalada for Lumen Learning.  Provided by : Lumen Learning.  License :  CC BY-SA: Attribution-ShareAlike
• Psychodynamic and Psychosocial Theories of Early Childhood . Authored by : Jessica Traylor for Lumen Learning.  Provided by : Lumen Learning.  License :  CC BY-SA: Attribution-ShareAlike
• “Psychosocial Development in Midlife.”   Authored by : Ronnie Mather for Lumen Learning.  Provided by : Lumen Learning.  License :  CC BY-SA: Attribution-ShareAlike

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Understanding Developmental Psychology

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Daniel B. Block, MD, is an award-winning, board-certified psychiatrist who operates a private practice in Pennsylvania.

• Seeking Treatment

Frequently Asked Questions

Change is inevitable. As humans, we constantly grow throughout our lifespans, from conception to death. The field of developmental psychology explores the behavioral, emotional, physical, and cognitive changes that happen as people age.

Psychologists strive to understand and explain how and why people change throughout life. While many of these changes are normal and expected, they can still pose challenges that people sometimes need extra assistance to manage.

The principles of normative development help professionals spot potential problems and provide early intervention for better outcomes. Developmental psychologists can work with people of all ages to address roadblocks and support growth, although some choose to specialize in a specific age group such as childhood, adulthood, or old age.

What Is Developmental Psychology?

Developmental psychology is the branch of psychology that focuses on how people grow and change over the course of a lifetime.

Those who specialize in this field are not just concerned with the physical changes that occur as people grow; they also look at the social, emotional, and cognitive development that occurs throughout life.

Some of the many issues developmental psychologists assist with include:

• Cognitive development during childhood and throughout life
• Developmental challenges and learning disabilities
• Emotional development
• Language acquisition
• Moral reasoning
• Motor skill development
• Personality development
• Self-awareness and self-concept
• Social and cultural influences on child development

These professionals spend a great deal of time investigating and observing how these processes occur under normal circumstances, but they are also interested in learning about things that can disrupt developmental processes.

By better understanding how and why people change and grow, developmental psychologists help people live up to their full potential. Understanding the course of normal human development and recognizing potential problems early on can prevent difficulties with depression, low self-esteem, frustration, and low achievement in school.

Developmental Psychology Theories

Developmental psychologists often utilize a number of theories to think about different aspects of human development. For example, a psychologist assessing intellectual development in a child might consider Piaget's theory of cognitive development , which outlined the key stages that children go through as they learn.

A psychologist working with a child might also want to consider how the child's relationships with caregivers influences his or her behaviors, and so turn to Bowlby's theory of attachment .

Psychologists are also interested in looking at how social relationships influence the development of both children and adults. Erikson's theory of psychosocial development and Vygotsky's theory of sociocultural development are two popular theoretical frameworks that address the social influences on the developmental process.

Each approach tends to stress different aspects of development such as mental, social, or parental influences on how children grow and progress .

When to See a Developmental Psychologist

While development tends to follow a fairly predictable pattern, there are times when things might go off course. Parents often focus on what are known as developmental milestones, which represent abilities that most children tend to display by a certain point in development. These typically focus on one of four different areas:

• Physical milestones
• Cognitive milestones
• Social/emotional milestones
• Communication milestones

For example, walking is one physical milestone that most children achieve sometime between the ages of 9 and 15 months. If a child is not walking or attempting to walk by 16 to 18 months, parents might consider consulting with their family physician to determine if a developmental issue might be present.

While all children develop at different rates, when a child fails to meet certain milestones by a certain age, there may be cause for concern.

By being aware of these milestones, parents can seek assistance, and healthcare professionals can offer interventions that can help kids overcome developmental delays.

These professionals often evaluate children to determine if a developmental delay might be present, or they might work with elderly patients who are facing health concerns associated with old age such as cognitive declines, physical struggles, emotional difficulties, or degenerative brain disorders.

Developmental psychologists can provide support to individuals at all points of life who may be facing developmental issues or problems related to aging.

Developmental Psychology Stages

As you might imagine, developmental psychologists often break down development according to various phases of life. Each of these periods of development represents a time when different milestones are typically achieved.

People may face particular challenges at each point, and developmental psychologists can often help people who might be struggling with problems to get back on track.

Prenatal Development

The prenatal period is of interest to developmental psychologists who seek to understand how the earliest influences on development can impact later growth during childhood. Psychologists may look at how primary reflexes emerge before birth, how fetuses respond to stimuli in the womb, and the sensations and perceptions that fetuses are capable of detecting prior to birth.

Developmental psychologists may also look at potential problems such as Down syndrome, maternal drug use, and inherited diseases that might have an impact on the course of future development.

Early Childhood Development

The period from infancy through early childhood is a time of remarkable growth and change. Developmental psychologists look at things such as the physical, cognitive, and emotional growth that takes place during this critical period of development.

In addition to providing interventions for potential developmental problems at this point, psychologists are also focused on helping kids achieve their full potential . Parents and healthcare experts are often on the lookout to ensure that kids are growing properly, receiving adequate nutrition, and achieving cognitive milestones appropriate for their age.

Middle Childhood Development

This period of development is marked by both physical maturation and the increased importance of social influences as children make their way through elementary school.

Kids begin to make their mark on the world as they form friendships, gain competency through schoolwork, and continue to build their unique sense of self. Parents may seek the assistance of a developmental psychologist to help kids deal with potential problems that might arise at this age including social, emotional, and mental health issues.

Adolescent Development

The teenage years are often the subject of considerable interest as children experience the psychological turmoil and transition that often accompanies this period of development. Psychologists such as Erik Erikson were especially interested in looking at how navigating this period leads to identity formation .

At this age, kids often test limits and explore new identities as they explore the question of who they are and who they want to be. Developmental psychologists can help support teens as they deal with some of the challenging issues unique to the adolescent period including puberty, emotional turmoil, and social pressure.

Early Adult Development

This period of life is often marked by forming and maintaining relationships. Critical milestones during early adulthood may include forming bonds, intimacy, close friendships, and starting a family.

Those who can build and sustain such relationships tend to experience connectedness and social support while those who struggle with such relationships may be left feeling alienated and lonely .

People facing such issues might seek the assistance of a developmental psychologist in order to build healthier relationships and combat emotional difficulties.

Middle Adult Development

This stage of life tends to center on developing a sense of purpose and contributing to society. Erikson described this as the conflict between generativity and stagnation .

Those who engage in the world, contribute things that will outlast them, and leave a mark on the next generation emerge with a sense of purpose. Activities such as careers, families, group memberships, and community involvement are all things that can contribute to this feeling of generativity.

Older Adult Development

The senior years are often viewed as a period of poor health, yet many older adults are capable of remaining active and busy well into their 80s and 90s. Increased health concerns mark this period of development, and some individuals may experience mental declines related to dementia.

Theorist Erik Erikson also viewed the elder years as a time of reflection back on life . Those who are able to look back and see a life well-lived emerge with a sense of wisdom and readiness to face the end of their lives, while those who look back with regret may be left with feelings of bitterness and despair.

Developmental psychologists may work with elderly patients to help them cope with issues related to the aging process.

Diagnosing Developmental Issues

To determine if a developmental problem is present, a psychologist or other highly trained professional may administer either a developmental screening or evaluation.

For children, such an evaluation typically involves interviews with parents and other caregivers to learn about behaviors they may have observed, a review of a child's medical history, and standardized testing to measure functioning in terms of communication, social/emotional skills, physical/motor development, and cognitive skills.

If a problem is found to be present, the patient may then be referred to a specialist such as a speech-language pathologist, physical therapist, or occupational therapist.

A Word From Verywell

Receiving a diagnosis of a developmental issue can often feel both confusing and frightening, particularly when it is your child who is affected. Once you or your loved one has received a diagnosis of a developmental issue, spend some time learning as much as you can about the diagnosis and available treatments.

Prepare a list of questions and concerns you may have and discuss these issues with your doctor, developmental psychologist, and other healthcare professionals who may be part of the treatment team. By taking an active role in the process, you will feel better informed and equipped to tackle the next steps in the treatment process.

The three major developmental psychology issues are focused on physical development, cognitive development, and emotional development.

The seven major stages of development are:

• Infant development
• Toddler development
• Preschool development
• Middle childhood development
• Adolescent development
• Early adult development
• Older adult development

The principles of developmental psychology outlined by Paul Baltes suggest that development is (1) lifelong, (2) multidimensional, (3) multidirectional, (4) involves gains and losses, (5) plastic, and that developmental psychology is (6) multidisciplinary.  

Four developmental issues that psychologists explore are focused on the relative contributions of:

• Nature vs. nurture : Is development primarily influenced by genetics or environmental factors?
• Early vs. later experience : Do early childhood events matter more than events that happen later in life?
• Continuity vs discontinuity : Is developmental change a gradual process or do changes happen suddenly and follow a specific course?
• Abnormal behavior vs. individual differences : What represents abnormal development and what can be considered individual variations in development?

Keenan T, Evans S. An Introduction to Child Development . 2nd ed. SAGE; 2009.

• Erikson EH. (1963).Childhood and Society. (2nd ed.). New York: Norton.
• Erikson EH. (1968).Identity: Youth and Crisis. New York: Norton.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Module 1: Lifespan Development

Defining human development, learning outcomes.

• Describe human development and its three domains: physical, cognitive, and psychosocial development
• Explain key human development issues about the nature of change: continuous/discontinuous, one course/multiple courses, and nature/nurture

Domains in Human Development

Figure 1 . Human development encompasses the physical, cognitive, and psychosocial changes that occur throughout a lifetime.

Physical Domain

Many of us are familiar with the height and weight charts that pediatricians consult to estimate if babies, children, and teens are growing within normative ranges of physical development. We may also be aware of changes in children’s fine and gross motor skills, as well as their increasing coordination, particularly in terms of playing sports. But we may not realize that physical development also involves brain development, which not only enables childhood motor coordination but also greater coordination between emotions and planning in adulthood, as our brains are not done developing in infancy or childhood. Physical development also includes puberty, sexual health, fertility, menopause, changes in our senses, and primary versus secondary aging. Healthy habits with nutrition and exercise are also important at every age and stage across the lifespan.

Cognitive Domain

If we watch and listen to infants and toddlers, we can’t help but wonder how they learn so much so fast, particularly when it comes to language development. Then as we compare young children to those in middle childhood, there appear to be huge differences in their ability to think logically about the concrete world around them. Cognitive development includes mental processes, thinking, learning, and understanding, and it doesn’t stop in childhood. Adolescents develop the ability to think logically about the abstract world (and may like to debate matters with adults as they exercise their new cognitive skills!). Moral reasoning develops further, as does practical intelligence—wisdom may develop with experience over time. Memory abilities and different forms of intelligence tend to change with age. Brain development and the brain’s ability to change and compensate for losses is significant to cognitive functions across the lifespan, too.

Psychosocial Domain

Development in this domain involves what’s going on both psychologically and socially. Early on, the focus is on infants and caregivers, as temperament and attachment are significant. As the social world expands and the child grows psychologically, different types of play and interactions with other children and teachers become important. Psychosocial development involves emotions, personality, self-esteem, and relationships. Peers become more important for adolescents, who are exploring new roles and forming their own identities. Dating, romance, cohabitation, marriage, having children, and finding work or a career are all parts of the transition into adulthood. Psychosocial development continues across adulthood with similar (and some different) developmental issues of family, friends, parenting, romance, divorce, remarriage, blended families, caregiving for elders, becoming grandparents and great grandparents, retirement, new careers, coping with losses, and death and dying.

As you may have already noticed, physical, cognitive, and psychosocial development are often interrelated, as with the example of brain development. We will be examining human development in these three domains in detail throughout the modules in this course, as we learn about infancy/toddlerhood, early childhood, middle childhood, adolescence, young adulthood, middle adulthood, and late adulthood development, as well as death and dying.

Who Studies Human Development and Why?

Many academic disciplines contribute to the study of development and this type of course is offered in some schools as psychology (particularly as developmental psychology); in other schools, it is taught under sociology, human development, or family studies. This multidisciplinary course is made up of contributions from researchers in the areas of health care, anthropology, nutrition, child development, biology, gerontology, psychology, and sociology, among others. Consequently, the stories provided are rich and well-rounded and the theories and findings can be part of a collaborative effort to understand human lives.

The main goals of those involved in studying human development are to describe and explain changes. Throughout this course, we will describe observations during development, then examine how theories provide explanations for why these changes occur. For example, you may observe two-year-old children to be particularly temperamental, and researchers offer theories to explain why that is. We’ll learn a lot more about theories, especially developmental theories, in the next module.

Key Issues in Human Development

• Is the change smooth or uneven (continuous versus discontinuous)?
• Is this pattern of change the same for everyone, or are there different patterns of change (one course of development versus many courses)?
• How do genetics and environment interact to influence development (nature versus nurture)?

Is Development Continuous or Discontinuous?

Continuous development views development as a cumulative process, gradually improving on existing skills (Figure 2). With this type of development, there is a gradual change. Consider, for example, a child’s physical growth: adding inches to their height year by year. In contrast, theorists who view development as discontinuous believe that development takes place in unique stages and that it occurs at specific times or ages. With this type of development, the change is more sudden, such as an infant’s ability to demonstrate awareness of object permanence (which is a cognitive skill that develops toward the end of infancy, according to Piaget’s cognitive theory—more on that theory in the next module).

Figure 2 . The concept of continuous development can be visualized as a smooth slope of progression, whereas discontinuous development sees growth in more discrete stages.

Is There One Course of Development or Many?

Is development essentially the same, or universal, for all children (i.e., there is one course of development) or does development follow a different course for each child, depending on the child’s specific genetics and environment (i.e., there are many courses of development)? Do people across the world share more similarities or more differences in their development? How much do culture and genetics influence a child’s behavior?

Stage theories hold that the sequence of development is universal. For example, in cross-cultural studies of language development, children from around the world reach language milestones in a similar sequence (Gleitman & Newport, 1995). Infants in all cultures coo before they babble. They begin babbling at about the same age and utter their first word around 12 months old. Yet we live in diverse contexts that have a unique effect on each of us. For example, researchers once believed that motor development followed one course for all children regardless of culture. However, childcare practices vary by culture, and different practices have been found to accelerate or inhibit the achievement of developmental milestones such as sitting, crawling, and walking (Karasik, Adolph, Tamis-LeMonda, & Bornstein, 2010).

For instance, let’s look at the Aché society in Paraguay. They spend a significant amount of time foraging in forests. While foraging, Aché mothers carry their young children, rarely putting them down in order to protect them from getting hurt in the forest. Consequently, their children walk much later: They walk around 23–25 months old, in comparison to infants in Western cultures who begin to walk around 12 months old. However, as Aché children become older, they are allowed more freedom to move about, and by about age 9, their motor skills surpass those of U.S. children of the same age: Aché children are able to climb trees up to 25 feet tall and use machetes to chop their way through the forest (Kaplan & Dove, 1987). As you can see, our development is influenced by multiple contexts, so the timing of basic motor functions may vary across cultures. However, the functions are present in all societies.

Figure 3. All children across the world love to play. Whether in (a) Florida or (b) South Africa, children enjoy exploring sand, sunshine, and the sea. (credit a: modification of work by “Visit St. Pete/Clearwater”/Flickr; credit b: modification of work by “stringer_bel”/Flickr)

How Do Nature and Nurture Influence Development?

Are we who we are because of nature (biology and genetics), or are we who we are because of nurture (our environment and culture)? This longstanding question is known in psychology as the nature versus nurture debate. It seeks to understand how our personalities and traits are the product of our genetic makeup and biological factors, and how they are shaped by our environment, including our parents, peers, and culture. For instance, why do biological children sometimes act like their parents—is it because of genetics or because of early childhood environment and what the child has learned from their parents? What about children who are adopted—are they more like their biological families or more like their adoptive families? And how can siblings from the same family be so different?

We are all born with specific genetic traits inherited from our parents, such as eye color, height, and certain personality traits. Beyond our basic genotype, however, there is a deep interaction between our genes and our environment. Our unique experiences in our environment influence whether and how particular traits are expressed, and at the same time, our genes influence how we interact with our environment (Diamond, 2009; Lobo, 2008). There is a reciprocal interaction between nature and nurture as they both shape who we become, but the debate continues as to the relative contributions of each.

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Developmental Psychology 101: Theories, Stages, & Research

You can imagine how vast this field of psychology is if it has to cover the whole of life, from birth through death.

Just like any other area of psychology, it has created exciting debates and given rise to fascinating case studies.

In recent years, developmental psychology has shifted to incorporate positive psychology paradigms to create a holistic lifespan approach. As an example, the knowledge gained from positive psychology can enhance the development of children in education.

In this article, you will learn a lot about different aspects of developmental psychology, including how it first emerged in history and famous theories and models.

Before you continue, we thought you might like to download our three Positive Psychology Exercises for free . These science-based exercises explore fundamental aspects of positive psychology, including strengths, values, and self-compassion, and will give you the tools to enhance the wellbeing of your clients, students, or employees.

This Article Contains:

What is developmental psychology, 4 popular theories, stages, & models, 2 questions and research topics, fascinating case studies & research findings, a look at positive developmental psychology, applying developmental psychology in education, resources from positivepsychology.com, a take-home message.

Human beings change drastically over our lifetime.

The American Psychological Association (2020) defines developmental psychology as the study of physical, mental, and behavioral changes, from conception through old age.

Developmental psychology investigates biological, genetic, neurological, psychosocial, cultural, and environmental factors of human growth (Burman, 2017).

Over the years, developmental psychology has been influenced by numerous theories and models in varied branches of psychology (Burman, 2017).

History of developmental psychology

Developmental psychology first appeared as an area of study in the late 19th century (Baltes, Lindenberger, & Staudinger, 2007). Developmental psychology focused initially on child and adolescent development, and was concerned about children’s minds and learning (Hall, 1883).

There are several key figures in developmental psychology. In 1877, the famous evolutionary biologist Charles Darwin undertook the first study of developmental psychology on innate communication forms. Not long after, physiologist William Preyer (1888) published a book on the abilities of an infant.

The 1900s saw many significant people dominating the developmental psychology field with their detailed theories of development: Sigmund Freud (1923, 1961), Jean Piaget (1928), Erik Erikson (1959), Lev Vygotsky (1978), John Bowlby (1958), and Albert Bandura (1977).

By the 1920s, the scope of developmental psychology had begun to include adult development and the aging process (Thompson, 2016).

In more recent years, it has broadened further to include prenatal development (Brandon et al., 2009). Developmental psychology is now understood to encompass the complete lifespan (Baltes et al., 2007).

Each of these models has contributed to the understanding of the process of human development and growth.

Furthermore, each theory and model focuses on different aspects of development: social, emotional, psychosexual, behavioral, attachment, social learning, and many more.

Here are some of the most popular models of development that have heavily contributed to the field of developmental psychology.

1. Bowlby’s attachment styles

The seminal work of psychologist John Bowlby (1958) showcased his interest in children’s social development. Bowlby (1969, 1973, 1980) developed the most famous theory of social development, known as attachment theory .

Bowlby (1969) hypothesized that the need to form attachments is innate, embedded in all humans for survival and essential for children’s development. This instinctive bond helps ensure that children are cared for by their parent or caregiver (Bowlby, 1969, 1973, 1980).

Bowlby’s original attachment work was developed further by one of his students, Mary Ainsworth. She proposed several attachment styles between the child and the caregiver (Ainsworth & Bell, 1970).

This theory clearly illustrates the importance of attachment styles to a child’s future development. Consistent and stable caregiving results in a secure attachment style (Ainsworth, Blehar, Waters, & Wall, 1978). In contrast, unstable and insecure caregiving results in several negative attachment styles: ambivalent, avoidant, or disorganized (Ainsworth & Bell, 1970; Main & Solomon, 1986).

Bowlby’s theory does not consider peer group influence or how it can shape children’s personality and development (Harris, 1998).

2. Piaget’s stage theory

Jean Piaget was a French psychologist highly interested in child development. He was interested in children’s thinking and how they acquire, construct, and use their knowledge (Piaget, 1951).

Piaget’s (1951) four-stage theory of cognitive development sequences a child’s intellectual development. According to this theory, all children move through these four stages of development in the same order (Simatwa, 2010).

The sensorimotor stage is from birth to two years old. Behaviors are triggered by sensory stimuli and limited to simple motor responses. If an object is removed from the child’s vision, they think it no longer exists (Piaget, 1936).

The pre-operational stage occurs between two and six years old. The child learns language but cannot mentally manipulate information or understand concrete logic (Wadsworth, 1971).

The concrete operational stage takes place from 7 to 11 years old. Children begin to think more logically about factual events. Abstract or hypothetical concepts are still difficult to understand in this stage (Wadsworth, 1971).

In the formal operational stage from 12 years to adulthood, abstract thought and skills arise (Piaget, 1936).

Piaget did not consider other factors that might affect these stages or a child’s progress through them. Biological maturation and interaction with the environment can determine the rate of cognitive development in children (Papalia & Feldman, 2011). Individual differences can also dictate a child’s progress (Berger, 2014).

3. Freud’s psychosexual development theory

One of the most influential developmental theories, which encompassed psychosexual stages of development, was developed by Austrian psychiatrist Sigmund Freud (Fisher & Greenberg, 1996).

Freud concluded that childhood experiences and unconscious desires influence behavior after witnessing his female patients experiencing physical symptoms and distress with no physical cause (Breuer & Freud, 1957).

According to Freud’s psychosexual theory, child development occurs in a series of stages, each focused on different pleasure areas of the body. During each stage, the child encounters conflicts, which play a significant role in development (Silverman, 2017).

Freud’s theory of psychosexual development includes the oral, anal, phallic, latent, and genital stages. His theory suggests that the energy of the libido is focused on these different erogenous zones at each specific stage (Silverman, 2017).

Freud concluded that the successful completion of each stage leads to healthy adult development. He also suggested that a failure to progress through a stage causes fixation and developmental difficulties, such as nail biting (oral fixation) or obsessive tidiness (anal fixation; Silverman, 2017).

Freud considered personality to be formed in childhood as a child passes through these stages. Criticisms of Freud’s theory of psychosexual development include its failure to consider that personality can change and grow over an entire lifetime. Freud believed that early experiences played the most significant role in shaping development (Silverman, 2017).

4. Bandura’s social learning theory

American psychologist Albert Bandura proposed the social learning theory (Bandura, Ross, & Ross, 1961). Bandura did not believe that classical or operant conditioning was enough to explain learned behavior because some behaviors of children are never reinforced (Bandura, 1986). He believed that children observe, imitate, and model the behaviors and reactions of others (Bandura, 1977).

Bandura suggested that observation is critical in learning. Further, the observation does not have to be of a live actor, such as in the Bobo doll experiment (Bandura, 1986). Bandura et al. (1961) considered that learning and modeling can also occur from listening to verbal instructions on behavior performance.

Bandura’s (1977) social theory posits that both environmental and cognitive factors interact to influence development.

Bandura’s developmental theory has been criticized for not considering biological factors or children’s autonomic nervous system responses (Kevin, 1995).

Overview of theories of development – Khan Academy

Developmental psychology has given rise to many debatable questions and research topics. Here are two of the most commonly discussed.

1. Nature vs nurture debate

One of the oldest debates in the field of developmental psychology has been between nature and nurture (Levitt, 2013).

Is human development a result of hereditary factors (genes), or is it influenced by the environment (school, family, relationships, peers, community, culture)?

The polarized position of developmental psychologists of the past has now changed. The nature/nurture question now concerns the relationship between the innateness of an attribute and the environmental effects on that attribute (Nesterak, 2015).

The field of epigenetics  describes how behavioral and environmental influences affect the expression of genes (Kubota, Miyake, & Hirasawa, 2012).

Many severe mental health disorders have a hereditary component. Yet, the environment and behavior, such as improved diet, reduced stress, physical activity, and a positive mindset, can determine whether this health condition is ever expressed (Śmigielski, Jagannath, Rössler, Walitza, & Grünblatt, 2020).

When considering classic models of developmental psychology, such as Piaget’s schema theory and Freud’s psychosexual theory, you’ll see that they both perceive development to be set in stone and unchangeable by the environment.

Contemporary developmental psychology theories take a different approach. They stress the importance of multiple levels of organization over the course of human development (Lomas, Hefferon, & Ivtzan, 2016).

2. Theory of mind

Theory of mind allows us to understand that others have different intentions, beliefs, desires, perceptions, behaviors, and emotions (American Psychological Association, 2020).

It was first identified by research by Premack and Woodruff (1978) and considered to be a natural developmental stage of progression for all children. Starting around the ages of four or five, children begin to think about the thoughts and feelings of others. This shows an emergence of the theory of mind (Wellman & Liu, 2004).

However, the ability of all individuals to achieve and maintain this critical skill at the same level is debatable.

Children diagnosed with autism exhibit a deficit in the theory of mind (Baron-Cohen, Leslie, & Frith, 1985).

Individuals with depression (psychotic and non-psychotic) are significantly impaired in theory of mind tasks (Wang, Wang, Chen, Zhu, & Wang, 2008).

People with social anxiety disorder have also been found to show less accuracy in decoding the mental states of others (Washburn, Wilson, Roes, Rnic, & Harkness, 2016).

Further research has shown that the theory of mind changes with aging. This suggests a developmental lifespan process for this concept (Meinhardt-Injac, Daum, & Meinhardt, 2020).

1. Little Albert

The small child who was the focus of the experiments of behavioral psychologists Watson and Rayner (1920) was referred to as ‘Little Albert.’ These experiments were essential landmarks in developmental psychology and showed how an emotionally stable child can be conditioned to develop a phobia.

Albert was exposed to several neutral stimuli including cotton wool, masks, a white rat, rabbit, monkey, and dog. Albert showed no initial fear to these stimuli.

When a loud noise was coupled with the initially neutral stimulus, Albert became very distressed and developed a phobia of the object, which extended to any similar object as well.

This experiment highlights the importance of environmental factors in the development of behaviors in children.

2. David Reimer

At the age of eight months, David Reimer lost his penis in a circumcision operation that went wrong. His worried parents consulted a psychologist, who advised them to raise David as a girl.

David’s young age meant he knew nothing about this. He went through the process of hormonal treatment and gender reassignment. At the age of 14, David found out the truth and wanted to reverse the gender reassignment process to become a boy again. He had always felt like a boy until this time, even though he was socialized and brought up as a girl (Colapinto, 2006).

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Contemporary theories of developmental psychology often encompass a holistic approach and a more positive approach to development.

Positive psychology has intersected with developmental disciplines in areas such as parenting, education, youth, and aging (Lomas et al., 2016).

These paradigms can all be grouped together under the umbrella of positive developmental psychology. This fresh approach to development focuses on the wellbeing aspects of development, while systematically bringing them together (Lomas, et al., 2016).

• Positive parenting is the approach to children’s wellbeing by focusing on the role of parents and caregivers (Latham, 1994).
• Positive education looks at flourishing in the context of school (Seligman, Ernst, Gillham, Reivich, & Linkins, 2009).
• Positive youth development is the productive and constructive focus on adolescence and early adulthood to enhance young people’s strengths and promote positive outcomes (Larson, 2000).
• Positive aging , also known as healthy aging, focuses on the positivity of aging as a healthy, normal stage of life (Vaillant, 2004).

Much of the empirical and theoretical work connected to positive developmental psychology has been going on for years, even before the emergence of positive psychology itself (Lomas et al., 2016).

We recommend this related article Applying Positive Psychology in Schools & Education: Your Ultimate Guide for further reading.

In the classroom, developmental psychology considers children’s psychological, emotional, and intellectual characteristics according to their developmental stage.

A report on the top 20 principles of psychology in the classroom, from pre-kindergarten to high school, was published by the American Psychological Association in 2015. The report also advised how teachers can respond to these principles in the classroom setting.

The top 5 principles and teacher responses are outlined in the table below.

There are many valuable resources to help you foster positive development no matter whether you’re working with young children, teenagers, or adults.

To help get you started, check out the following free resources from around our blog.

• Adopt A Growth Mindset This exercise helps clients recognize instances of fixed mindset in their thinking and actions and replace them with thoughts and behaviors more supportive of a growth mindset.
• Childhood Frustrations This worksheet provides a space for clients to document key challenges experienced during childhood, together with their emotional and behavioral responses.
• What I Want to Be This worksheet helps children identify behaviors and emotions they would like to display and select an opportunity in the future to behave in this ideal way.
• 17 Positive Psychology Exercises If you’re looking for more science-based ways to help others enhance their wellbeing, this signature collection contains 17 validated positive psychology tools for practitioners. Use them to help others flourish and thrive.
• Developmental Psychology Courses If you are interested in a career in Developmental Psychology , we suggest 15 of the best courses in this article.

17 Top-Rated Positive Psychology Exercises for Practitioners

Expand your arsenal and impact with these 17 Positive Psychology Exercises [PDF] , scientifically designed to promote human flourishing, meaning, and wellbeing.

Created by Experts. 100% Science-based.

Earlier developmental psychology models and theories were focused on specific areas, such as attachment, psychosexual, cognitive, and social learning. Although informative, they did not take in differing perspectives and were fixed paradigms.

We’ve now come to understand that development is not fixed. Individual differences take place in development, and the factors that can affect development are many. It is ever changing throughout life.

The modern-day approach to developmental psychology includes sub-fields of positive psychology. It brings these differing disciplines together to form an overarching positive developmental psychology paradigm.

Developmental psychology has helped us gain a considerable understanding of children’s motivations, social and emotional contexts, and their strengths and weaknesses.

This knowledge is essential for educators to create rich learning environments for students to help them develop positively and ultimately flourish to their full potential.

We hope you enjoyed reading this article. Don’t forget to download our three Positive Psychology Exercises for free .

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Home / Online Bachelor’s Degree Programs / Online Bachelor’s in Human Development and Family Studies / Bachelor’s in Human Development and Family Studies Resources / Stages of Human Development: What It Is & Why It’s Important

What Is Human Development and Why Is It Important? What Is Human Development and Why Is It Important? What Is Human Development and Why Is It Important?

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Tables of Contents

• Eight Stages of Human Development?
• Theories of Human Development

Human Development vs. Developmental Psychology

What are the genetic factors that affect human growth and development, why do we study human growth and development.

Imagine two children born in the same town and the same year to families with similar socioeconomic statuses. One child grows up to be assertive and confident, while the other grows up to be timid and shy. The study of the stages of human development can help explain the reasons for these differences and much more.

What is human development, exactly? Human development is a branch of psychology with the goal of understanding people — how they develop, grow, and change throughout their lives. This discipline, which can help individuals better understand themselves and their relationships, is broad. As such, it can be used in various professional settings and career paths.

What Are the Eight Stages of Human Development?

If human development is the study of how people change throughout their lives, how and when does this development happen? Many scientists and psychologists have studied various aspects of human development, including ego psychologist Erik Erikson. He examined the impact of social experiences throughout an individual’s life and theorized that  psychosocial development happens in eight sequential parts . What are the eight stages of human development?

Stage 1 — Infancy: Trust vs. Mistrust

In the first stage of human development, infants learn to trust based on how well their caregivers meet their basic needs and respond when they cry. If an infant cries out to be fed, the parent can either meet this need by feeding and comforting the infant or not meet this need by ignoring the infant. When their needs are met, infants learn that relying on others is safe; when their needs go unmet, infants grow up to be less trusting.

Stage 2 — Toddlerhood: Autonomy vs. Shame and Doubt

In addition to autonomy versus shame and doubt, another way to think of the second stage is independence versus dependence. Like in the first stage, toddlers go through this stage responding to their caregivers. If caregivers encourage them to be independent and explore the world on their own, toddlers will grow up with a sense of self-efficacy. If the caregivers hover excessively or encourage dependence, these toddlers grow up with less confidence in their abilities.

For example, if a toddler wants to walk without assistance in a safe area, the caregiver should encourage this autonomy by allowing the independent behavior. If the caregiver insists on holding the toddler’s hand even when it’s not necessary, this attention can lead to doubt later in life.

Stage 3 — Preschool Years: Initiative vs. Guilt

During the preschool years, children learn to assert themselves and speak up when they need something. Some children may state that they’re sad because a friend stole their toy. If this assertiveness is greeted with a positive reaction, they learn that taking initiative is helpful behavior. However, if they’re made to feel guilty or ashamed for their assertiveness, they may grow up to be timid and less likely to take the lead.

Stage 4 — Early School Years: Industry vs. Inferiority

When children begin school, they start to compare themselves with peers. If children feel they’re accomplished in relation to peers, they develop strong self-esteem. If, however, they notice that other children have met milestones that they haven’t, they may struggle with self-esteem. For example, a first grader may notice a consistently worse performance on spelling tests when compared with peers. If this becomes a pattern, it can lead to feelings of inferiority.

The key components of Erikson’s model of human development include stage one, infancy, trust versus mistrust; stage two, toddlerhood, autonomy versus shame and doubt; stage three, preschool years, initiative versus guilt; stage four, early school years, industry versus inferiority; stage five, adolescence, identity versus role confusion; stage six, young adulthood, intimacy versus isolation; stage seven, middle adulthood, generativity versus stagnation; and stage eight, late adulthood, integrity versus despair.

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Stage 5 — Adolescence: Identity vs. Role Confusion

The adolescent stage is where the term “identity crisis” originated, and for good reason. Adolescence is all about developing a sense of self. Adolescents who can clearly identify who they are grow up with stronger goals and self-knowledge than teenagers who struggle to break free of their parents’ or friends’ influences. Adolescents who still deeply depend on their parents for social interaction and guidance may experience more role confusion than teenagers who pursue their own interests.

Stage 6 — Young Adulthood: Intimacy vs. Isolation

In young adulthood, which begins roughly at age 20, people begin to solidify their lifelong bonds; many people enter committed relationships or marriages, while others form lifelong friendships. People who can create and maintain these relationships reap the emotional benefits, while those who struggle to maintain relationships may suffer from isolation. A young adult who develops strong friendships in college may feel more intimacy than one who struggles to form and maintain close friendships.

Stage 7 — Middle Adulthood: Generativity vs. Stagnation

In middle adulthood, people tend to struggle with their contributions to society. They may be busy raising children or pursuing careers. Those who feel that they’re contributing experience generativity, which is the sense of leaving a legacy. On the other hand, those who don’t feel that their work or lives matter may experience feelings of stagnation. For example, a middle-aged adult who’s raising a family and working in a career that presumably helps people may feel more fulfilled than an adult who’s working at a day job that feels meaningless.

Stage 8 — Late Adulthood: Integrity vs. Despair

As adults reach the end of life, they look back on their lives and reflect. Adults who feel fulfilled by their lives, either through a successful family or a meaningful career, reach ego integrity, in which they can face aging and dying with peace. If older adults don’t feel that they’ve lived a good life, they risk falling into despair.

Other Theories of Human Development

Although widely used, Erikson’s psychosocial development theory has been critiqued for focusing too much on childhood. Critics claim that his emphasis makes the model less representative of the growth that people experienced in adulthood. Erikson’s model of the stages of human development is only one theory addressing growth and change throughout life, as many other psychologists have researched their own  theories of human development , including the following:

Cognitive Development

Jean Piaget developed the theory of cognitive development. Piaget’s theory is widely used in education programs to prepare teachers to instruct students in developmentally appropriate ways. The theory is based on four stages:

• Sensorimotor —  In the sensorimotor stage (birth to 2 years old), children learn object permanence, which is the understanding that people and objects still exist even when they’re out of view.
• Preoperational —  In the preoperational stage (2-7 years old), children develop symbolic thought, which is when they begin to progress from concrete to abstract thinking. Children in this stage often have imaginary friends.
• Concrete operational —  In the concrete operational stage (7-11 years old), children solidify their abstract thinking and begin to understand cause and effect and logical implications of actions.
• Formal operational —  In the formal operational stage (adolescence to adulthood), humans plan for the future, think hypothetically, and assume adult responsibilities.

Moral Development

Lawrence Kohlberg created a theory of human development based on moral development concepts. The theory comprises the following stages:

• Preconventional —  In the preconventional stage, people follow rules because they’re afraid of punishment and make choices only with their best interests in mind.
• Conventional —  In the conventional stage, people act to avoid society’s judgment and follow rules to maintain the systems and structures that are already in place.
• Postconventional —  In the postconventional stage, a genuine concern for the welfare of others and the greater good of society guides people.

Psychosexual Theory

Sigmund Freud popularized the  psychosexual theory . The theory comprises five stages:

• Oral —  In the oral stage (birth to 1 year old), children learn to suck and swallow and may experience conflict with weaning.
• Anal —  In the anal stage (1-3 years old), children learn to withhold or expel feces and may experience conflict with potty training.
• Phallic —  In the phallic stage (3-6 years old), children discover that their genitals can give them pleasure.
•   Latency —  In the latency stage (roughly 6 years old through puberty), they take a break from these physical stages and instead develop mentally and emotionally.
• Genital —  In the genital stage (puberty through adulthood), people learn to express themselves sexually.

Ideally, children move through each phase fluidly as their sexual libidos develop, but if they’re stuck in any of the phases, they may develop a fixation that hinders their development.

Behavioral Theory

The behavioral theory focuses solely on a person’s behaviors rather than the feelings that go alongside those behaviors. It suggests that behaviors are conditioned in an environment due to certain stimuli. Behavioral theorists believe that behavior determines feelings, so changing behaviors is important because this will in turn change feelings.

The  attachment theory  focuses on the deep relationships between people across their lifetime. An important attachment theory finding is that children must develop at least one strong bond in childhood to trust and develop relationships as adults. The attachment theory comprises four stages:

• Asocial or  pre-attachment   (birth to 6 weeks old)
• Indiscriminate attachment (6 weeks old to 7 months old)
• Specific or discriminate attachment (7-9 months old)
• Multiple attachments (10 months old or later)

Social Learning Theory

The social learning theory builds upon the behavioral theory and postulates that people learn best by observing the behavior of others. They watch how others act, view the consequences, and then make decisions regarding their own behavior accordingly. The four stages in this theory are:

• Reproduction

In the attention stage, people first notice the behavior of others. In the retention stage, they remember the behavior and the resulting consequences. In the reproduction stage, people develop the ability to imitate the behaviors they want to reproduce, and in the motivation stage, they perform these behaviors.

Sociocultural Theory

The  sociocultural theory  ties human development to the society or culture in which people live. It focuses on the contributions that society as a whole makes to individual human development. For example, children who are raised to play outdoors develop differently from children who are raised to play indoors.

An important part of this theory is the zone of proximal development, which is an area of knowledge and skills slightly more advanced than a child’s current level. The zone of proximal development helps teachers think about and plan instruction, so sociocultural theory plays a large role in preservice teacher training.

Resources: More Information on Theories of Human Development

• BetterHelp, “Behavioral Theory, Behavioral Psychology, or Behaviorism? How Behavior and Personality Intersect ”
• Encyclopedia Britannica, “Lawrence Kohlberg’s Stages of Moral Development”
• Healthline, “What Are Freud’s Psychosexual Stages of Development?”
• PositivePsychology.com, “What Is Attachment Theory? Bowlby’s 4 Stages Explained”
• Psychology Today , Social Learning Theory
• SimplyPsychology, “Lev Vygotsky’s Sociocultural Theory”
• SimplyPsychology, Theories of Psychology
• Verywell Mind, “The 4 Stages of Cognitive Development”

What are the differences between human development and developmental psychology? These terms are closely related. In fact, the study of developmental psychology is most people’s entry into human development.

Developmental psychology  is defined as a scientific approach to explaining growth, change, and consistency throughout a lifetime. It uses various frameworks to understand how people develop and transform throughout their lives. The goals of developmental psychology are to describe, explain, and optimize development to improve people’s lives. In the real world, developmental psychology is used in the study of physical, psychological, emotional, social, personality, and perceptual development.

The  study of developmental psychology  can lead to careers in several different fields. Developmental psychologists often work in colleges and universities and focus on research and teaching. Others work in healthcare facilities, clinics, assisted living facilities, hospitals, mental health clinics, or homeless shelters. In these applied settings, their focus is more on assessing, evaluating, and treating people. According to June 2020 data from PayScale, developmental  psychologists earn an average annual salary of about $68,000 .

One more key element of human growth and development left to explore is  genetics . Genetics influences the speed and way in which people develop, though other factors, such as parenting, education, experiences, and socioeconomic factors, are also at play. The multiple genetic factors that affect human growth and development include genetic interactions and sex chromosome abnormalities.

Genetic Interactions

Genes can act in an additive way or sometimes conflict with one another. For example, a child with one tall parent and one short parent may end up between the two of them, at average height. Other times, genes follow a dominant-recessive pattern. If one parent has brown hair and the other has red hair, the red hair gene is the dominant gene if their child has red hair.

Gene-Environment Interactions

Humans’ genetic information is always interacting with the environment, and sometimes this can impact development and growth. For example, if a child in utero is exposed to drugs, the child’s cognitive abilities may be impacted, thus changing the developmental process. In addition, even if a child’s genes would indicate a tall height, if that child experiences poor nutrition as children, it may impact their height.

Sex Chromosome Abnormalities

Sex chromosome abnormalities impact as many as 1 in 500 births. The following syndromes are examples of sex chromosome abnormalities that can impact development:

• Klinefelter syndrome  is the presence of an extra X chromosome in males, which can cause physical characteristics such as decreased muscle mass and reduced body hair and may cause learning disabilities.
• Fragile X syndrome  is caused by a mutation in the FMR1 gene that makes the X chromosome  appear fragile . It can cause intellectual disability, developmental delays, or distinctive physical features such as a long face.
• Turner syndrome  happens when one of the X chromosomes is missing or partially missing. It only affects females and results in physical characteristics like short stature and webbed neck.

Down Syndrome

Down syndrome  is another common example of how genetics can impact development. This chromosomal disorder may cause some individuals to experience physical or intellectual development differences. Down syndrome occurs at the 21st chromosomal site, in which people with Down syndrome have three chromosomes rather than two.

Those with Down syndrome often have different physical characteristics and may be prone to physical problems like heart defects and hearing problems. Most individuals with Down syndrome have intellectual impairment, but the degree of this impairment varies from person to person.

The top reasons for studying human development are to gain an understanding of your own life experience, help others understand what they’re going through, understand the relationship of society and individual growth, lead more effectively, and support the physical and mental health of others.

The study of human growth and development offers a wealth of value for personal and professional growth and understanding. Many reasons exist for why we study human growth and development.

Common benefits include the following:

• To  gain a better understanding  of one’s own life experiences. This can help people personally reach an understanding of what childhood events shaped their adulthood.
• To  gain knowledge  of how social context impacts development. This knowledge can be invaluable for professionals like teachers as they gain a deeper understanding of their students.
• To  help others understand and contextualize  the ups and downs of life. This helps therapists and psychologists better aid their clients in self-discovery.
• To  understand how societal change can support growth  and development. This understanding helps decision-makers in schools change the educational culture for the better.
• To  become a more effective research, teacher, or leader  in many different industries. Understanding human development deeply and in context has many professional benefits that can lead to greater insight.
• To  support the physical and mental health of individuals  throughout their life span. Professionals like doctors, nurses, and therapists must understand human growth and development to better support their clients.

Students may choose to study human growth and development because of its array of applications across many professional fields. For example, students who want to become elementary school teachers may take courses on the stages of human development to understand cognitive development and how children’s brains grow and change.

Human development is a wide-reaching and ever-changing discipline. A knowledge of human development can be invaluable to people personally as they continue to learn and grow throughout their lives and professionally as they learn to apply what they’ve learned to their careers.

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VeryWell Mind, “5 Reasons to Study Human Development”

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Encyclopedia of Quality of Life and Well-Being Research pp 462–465 Cite as

Bioecological Theory of Human Development

• Matthew Waugh 2 &
• Martin Guhn 3  
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• First Online: 01 January 2024

Bioecological model

The bioecological theory of human development (Bronfenbrenner 1986b ; Bronfenbrenner and Ceci 1993 , 1994 ; Bronfenbrenner and Morris 2006 ) is a comprehensive theoretical and methodological model for the study of human development. Extending on earlier ecological models of development (Bronfenbrenner 1979 , 1989 , 1986a , b ), the bioecological theory expounds on the biopsychological features of the “developing person” and on the capability for proximal processes to differentiate and actualize biological potential (Bronfenbrenner and Ceci 1993 , 1994 ; Bronfenbrenner and Morris 2006 ). The bioecological theory of human development has progressed through periodic revisions since its first comprehensive formulation in 1970 by one of the twentieth century’s most prominent developmental psychology theoretician, and Head Start cofounder, Urie Bronfenbrenner (1917–2005). Bronfenbrenner envisioned that his bioecological theory be relevant for practice, science,...

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Bronfenbrenner, U. (1970). Children and parents (pp. 241–255). Washington, DC: U.S. Government Printing Office (Report of Forum 15).

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Bronfenbrenner, U. (1986b). Ecology of the family as a context for human development. Developmental Psychology, 22 , 723–742.

Bronfenbrenner, U. (1989). Ecological systems theory. Annals of Child Development, 6 , 187–249.

Bronfenbrenner, U. (2001a). Growing chaos in the lives of children, youth, and families: How can we turn it around? In Author (Ed.), Making human beings human: Bioecological perspectives on human development (pp. 185–197). Thousand Oaks: Sage Publications. (Reprinted from Parenthood in America , pp. 197–210, by J. C. Westman, Ed., Madison: University of Wisconsin Press).

Bronfenbrenner, U. (2001b). The bioecological theory of human development. In Author (Ed.), Making human beings human: Bioecological perspectives on human development (pp. 3–15). Thousand Oaks: Sage Publications. Reprinted from International encyclopedia of the social and behavioral sciences , pp. 6963–6970, by N. J. Smelser & P. B. Baltes Eds., New York, NY: Elsevier.

Bronfenbrenner, U., & Ceci, S. J. (1993). Heredity, environment and the question “How?”: A first approximation. In Author (Ed.), Making human beings human: Bioecological perspectives on human development (pp. 174–184). Thousand Oaks: Sage Publications. Reprinted from Nature, nurture, and psychology , pp. 313–323, by R. Plomin & G. E. McClearn, Eds., 1995, Washington, DC: APA Books.

Bronfenbrenner, U., & Ceci, S. J. (1994). Nature-nurture reconceptualised: A bio-ecological model. Psychological Review, 10 (4), 568–586. https://doi.org/10.1037/0033-295X.101.4.568 .

Bronfenbrenner, U., & Evans, G. W. (2000). Developmental science in the 21st century: Emerging questions, theoretical models, research designs, and empirical findings. Social Development, 9 , 15–25. https://doi.org/10.1111/1467-9507.00114 .

Bronfenbrenner, U., & Morris, P. (1998). The ecology of developmental processes. In W. Damon & R. M. Lerner (Eds.), Handbook of child psychology: Vol. 1 Theoretical models of human development (5th ed., pp. 993–1028). New York: Wiley.

Bronfenbrenner, U., & Morris, P. (2006). The bioecological model of human development. In W. Damon & R. M. Lerner (Eds.), Handbook of child psychology: Vol. 1. Theoretical models of human development (6th ed., pp. 793–828). Hoboken: Wiley.

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• How to Write a Strong Hypothesis | Steps & Examples

How to Write a Strong Hypothesis | Steps & Examples

Published on May 6, 2022 by Shona McCombes . Revised on November 20, 2023.

A hypothesis is a statement that can be tested by scientific research. If you want to test a relationship between two or more variables, you need to write hypotheses before you start your experiment or data collection .

Example: Hypothesis

Daily apple consumption leads to fewer doctor’s visits.

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What is a hypothesis, developing a hypothesis (with example), hypothesis examples, other interesting articles, frequently asked questions about writing hypotheses.

A hypothesis states your predictions about what your research will find. It is a tentative answer to your research question that has not yet been tested. For some research projects, you might have to write several hypotheses that address different aspects of your research question.

A hypothesis is not just a guess – it should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations and statistical analysis of data).

Variables in hypotheses

Hypotheses propose a relationship between two or more types of variables .

• An independent variable is something the researcher changes or controls.
• A dependent variable is something the researcher observes and measures.

If there are any control variables , extraneous variables , or confounding variables , be sure to jot those down as you go to minimize the chances that research bias  will affect your results.

In this example, the independent variable is exposure to the sun – the assumed cause . The dependent variable is the level of happiness – the assumed effect .

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Step 1. Ask a question

Writing a hypothesis begins with a research question that you want to answer. The question should be focused, specific, and researchable within the constraints of your project.

Step 2. Do some preliminary research

Your initial answer to the question should be based on what is already known about the topic. Look for theories and previous studies to help you form educated assumptions about what your research will find.

At this stage, you might construct a conceptual framework to ensure that you’re embarking on a relevant topic . This can also help you identify which variables you will study and what you think the relationships are between them. Sometimes, you’ll have to operationalize more complex constructs.

Step 3. Formulate your hypothesis

Now you should have some idea of what you expect to find. Write your initial answer to the question in a clear, concise sentence.

4. Refine your hypothesis

You need to make sure your hypothesis is specific and testable. There are various ways of phrasing a hypothesis, but all the terms you use should have clear definitions, and the hypothesis should contain:

• The relevant variables
• The specific group being studied
• The predicted outcome of the experiment or analysis

5. Phrase your hypothesis in three ways

To identify the variables, you can write a simple prediction in  if…then form. The first part of the sentence states the independent variable and the second part states the dependent variable.

In academic research, hypotheses are more commonly phrased in terms of correlations or effects, where you directly state the predicted relationship between variables.

If you are comparing two groups, the hypothesis can state what difference you expect to find between them.

6. Write a null hypothesis

If your research involves statistical hypothesis testing , you will also have to write a null hypothesis . The null hypothesis is the default position that there is no association between the variables. The null hypothesis is written as H 0 , while the alternative hypothesis is H 1 or H a .

• H 0 : The number of lectures attended by first-year students has no effect on their final exam scores.
• H 1 : The number of lectures attended by first-year students has a positive effect on their final exam scores.

If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

• Sampling methods
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A hypothesis is not just a guess — it should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations and statistical analysis of data).

Null and alternative hypotheses are used in statistical hypothesis testing . The null hypothesis of a test always predicts no effect or no relationship between variables, while the alternative hypothesis states your research prediction of an effect or relationship.

Hypothesis testing is a formal procedure for investigating our ideas about the world using statistics. It is used by scientists to test specific predictions, called hypotheses , by calculating how likely it is that a pattern or relationship between variables could have arisen by chance.

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Human growth and development.

Palanikumar Balasundaram ; Indirapriya Darshini Avulakunta .

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Last Update: March 8, 2023 .

• Continuing Education Activity

Evaluation of growth and development is a crucial element in the physical examination of a patient. A piece of good working knowledge and the skill to evaluate growth and development are necessary for any patient's diagnostic workup. The early recognition of growth or developmental failure helps for effective intervention in managing a patient's problem. This activity reviews the various aspects of human growth and development and highlights the interprofessional team's role in assessing the kids for growth and developmental delay.

• Describe the stages of growth and development.
• Review the factors affecting growth and development.
• Outline the methods for growth measurements and standard screening tools for developmental assessment.
• Explain how interprofessional collaboration and communication can improve patient outcomes when assessing a patient's physical development.
• Introduction

In the context of childhood development, growth is defined as an irreversible constant increase in size, and development is defined as growth in psychomotor capacity. Both processes are highly dependent on genetic, nutritional, and environmental factors.  Evaluation of growth and development is a crucial element in the physical examination of a patient. A piece of good working knowledge and the skills to evaluate growth and development are necessary for any patient's diagnostic workup. The early recognition of growth or developmental failure helps for effective intervention in managing a patient's problem.

Stages in Human Growth and Development 

• Fetal stage: Fetal health issues can have detrimental effects on postnatal growth. One-third of neonates with intrauterine growth retardation might have curtailed postnatal growth. [1]  Good perinatal care is an essential factor in promoting fetal health and indirectly postnatal growth.
• Infancy (neonate and up to one year age)
• Toddler ( one to five years of age)
• Childhood (three to eleven years old) - early childhood is from three to eight years old, and middle childhood is from nine to eleven years old. 
• Adolescence or teenage (from 12 to 18 years old)

Factors Affecting Growth and Development 

The growth and development are positively influenced by factors, like parental health and genetic composition, even before conception. [3]

• Genetic factors play a primary role in growth and development. The genetic factors influencing height is substantial in the adolescence phase. [4]  A large longitudinal cohort study of 7755 Dutch twin pairs has suggested that the additive genetic factors predominantly explained the phenotypic correlations across the ages for height and body mass index. [5]  
• Fetal health has a highly influential role in achieving growth and development. Any stimulus or insult during fetal development causes developmental adaptations that produce permanent changes in the latter part of life.
• After birth, the environmental factors may exert either a beneficial or detrimental effect on growth. [6]
• Socioeconomic factors: Children of higher socio-economical classes are taller than the children of the same age and sex in the lower socioeconomic groups. Urbanization has positively influenced growth. The secular trend is observed in growth where the kids grow taller and mature more rapidly than the previous generation. This secular trend is observed significantly in developed countries like North America.
• The family characteristics: Higher family education levels have a positive impact on growth. The inadequate emotional support and inadequate developmental stimulus, including language training, might cause growth and development deterioration. 
• The human-made environment influences human growth and development significantly. Certain ongoing studies have proven the relationship of pollutants in sexual maturation, obesity, and thyroid function. [7]  The excess lead exposure antenatally significantly associates with low birth weight. Noise pollution due to transportation sources also has an association with reduced prenatal growth. 
• Nutrition  
• Malnutrition plays a detrimental role in the process of growth and development. 
• Deficiencies of trace minerals can affect growth and development. [8]  Iron deficiency usually affects psychomotor development and does not affect growth. Zinc deficiency might cause growth retardation and developmental delay. Selenium, iodine, manganese, and copper also play a significant role. 
• Growth faltering or rapid weight gain in early childhood influences health in the later part of life. The diet in early childhood has a strong association with the likelihood of obesity later in life. 'Early Protein Hypothesis' shows that lowering the protein supply during infancy helps achieve normal growth and reduce obesity in early childhood. [9]  This concept of the early protein hypothesis helps in improving the food products for children. 
• Genetic and environmental factors influence the growth and development in a perplexing interrelated pathway. Genetic and environmental risk factors are not mutually exclusive. Plasticity is the potential of a specific genotype to bring out diversified phenotypes in response to diverse environmental factors. [10]  The developmental plasticity can happen from the embryonic stage to adolescence and can be passed onto the next generation. 
• Role of experience during early childhood: Exposure to adverse experiences in early childhood might hinder development. Profound neglect during early childhood can impair development. Children adopted before six months of age have similar development when compared to their non-adoptive siblings. If children adopted after six months have a high risk of cognition deficits, behavioral issues, autism, and hyperactivity. [11]  Early intervention for children with adverse experiences is the pillar in healthy development.
• Issues of Concern

Measurement of Growth

Anthropometry is the gold standard by which clinicians can assess nutritional status. The major anthropometric measurements for age up to 2 years are weight, length, weight for length, and head circumference. The major measurements used for children above two years are weight, height, body mass index (BMI), and head circumference for the 2-3 years age group. 

• Length or height:  For children less than two years or children with severe cerebral palsy, the length is the ideal way of measuring stature. Length is measured by placing the child supine on an infant measuring board. For children aged more than two years, standing height is measured in the stadiometer after removing shoes. The supine length is usually 1 cm higher than standing height. Length and height can be documented to the closest 0.1 cm. For children with severe cerebral palsy or spinal deformities, upper arm length, tibial length, and knee height can be useful to assess stature. [12]
• Weight:  The kids below one year are weighed on a scale after removing the clothes, shoes, diaper, and documented to the closest 0.01 kg. The kids outside the infancy phase should be measured without shoes, with little or no outer clothing, and documented to the closest 0.1 kg. 
• Head circumference or occipitofrontal circumference:  Head circumference is assessed by measuring the largest area from the prominent site at the back (occiput) to the frontal prominence above the supraorbital ridge. Brain growth is maximum in the first three years of life, so head circumference is used in children less than three years.  It is measured as the maximum diameter through the supraorbital ridge to the occiput and documented to the closest 0.01 cm. Microcephaly is more than two standard deviations below the mean. Macrocephaly is more than two standard deviations above the mean. 
• < 5th percentile - underweight 
• 5th to 84th percentile - normal 
• 85th to 95th percentile - overweight 
• 95th to 98th percentile - obesity 
• More than 99th percentile - severe obesity
• The weight to length ratio is an alternative for body mass index in predicting adiposity in less than two years. 
• Self-assessment of the hip to waist ratio can help to guide the measure of central adiposity,
• Triceps and subscapular skinfolds can also be a useful measure of adiposity. [13]
• The upper segment to lower segment (U/L) ratio is 1.7 at birth, 1.3 at three years, and reaches 1.0 at greater than seven years. A higher U/L ratio is a feature in short-limb dwarfism.
• Arm span to height ratio is a fixed ratio across all ages. The ratio of more than 1.05:1 is suggestive of Marfan syndrome. [14]
• Sexual maturity:  Tanner's stage can be used to assess sexual maturity.
• Skeletal maturity:  Bone age can be determined by doing Hand & Wrist radiographs from 3 to 18 years of age. 
• Dental assessment:  Primary tooth eruption begins with the central incisors at six months. No single tooth by 13 months of age is of concern. Permanent tooth eruption starts at six years of age and continues up to 18 years of age. 

Growth Velocity 

The growth velocity is different at different stages of life. Also, different tissues grow at different rates at the same stage of life. The lymphoid tissues can exceed adult size at six years of age. Girls are taller than boys at 12 to 14 years, but later they will not grow taller than their boy's counterpart. Growth velocity is maximum during infancy and adolescence. The head circumference reaches closer to adult size by six years of age. The prepubertal height velocity of less than 4 cm per year is of concern. During puberty, the height velocity is 10 to 12 cm per year in boys and 8 to 10 cm per year in girls. The prepubertal weight velocity of less than 1 kg per year is of concern. Weight velocity is highest during puberty, up to 8 kg per year.

Stages of Development

Development is a continuous process from neonatal to adulthood. Though the growth ceases after adolescence, adolescence is not the end for development. Each developmental stage has a new set of challenges and opportunities. 

• Infancy : Development progress in cephalo-caudal direction and also from the midline to the lateral direction.  A three to four-month variation can be there in achieving the developmental milestone. Social development is a cortical function that develops earlier than motor skills. Lack of social smile by four weeks is of concern. At birth, the infant is equipped with primitive reflexes. Certain primitive reflexes help in the normal physiology of infants. Sucking and rooting reflex helps inefficient feeding. Most of the primitive reflex disappears to facilitate the mature development process. For example, the grasp reflex disappears by six months, and the child develops mature grasp development from 6-12 months.
• Early and late childhood: Between ages 1 and 3 years, locomotion and language are crucial. The best predictor of cognitive function is language. Fine motor skills are related to self-help skills. The most common development in early childhood is to establish self-identity. A child may have independent existence by three years of age. The kids learn independent existence skills like feeding behavior, toilet training, and self dressing during this stage of early and late childhood. Questioning skills develop during early childhood development.   
• Adolescence:  Adolescence is hallmarked by puberty changes, which occur two years earlier in females than in males. Puberty changes are assessed using the Tanner staging. Acceptance of a new body and separation from home, and establishing oneself as an independent adult in society are the significant challenges in puberty.

Psychosocial Development 

Erikson has postulated eight stages of psychosocial development.

• Trust and mistrust in infancy (< 1 year):  Infants develop trust with a warm response from the caretaker.  
• Autonomy and doubt in the toddler age group ( one to three years):   Children feel autonomous if caregivers encourage independence. Otherwise, they will doubt their abilities.
• Initiative and guilt in the preschool age group (three to six years):  By imaginative play, kids experiment with their ambitions. If parents do not encourage their initiative, the kids will feel guilt.  
• Industry and inferiority in early school years:  In school, children learn to work as a group. They will have inferiority feelings if the peer environment is hostile.
• Identity and role confusion in adolescence:  Self-identity is a significant development during adolescence. 
• Intimacy and isolation in early adulthood:  Those who cannot establish relationships or intimacy are prone to be socially isolated.
• Generativity and stagnation in middle adulthood:  Parenting is the best example to guide the younger generation. 
• Ego integrity and despair in late adulthood:  People who are not satisfied with what they did during their lifetime will be in despair.
• Clinical Significance

Understanding normal growth and development milestones are important for a clinician evaluating pediatric patients. It isn't easy to recognize aberrance if you are not familiar with normal. By using growth charts and doing the developmental screening, oftentimes, challenges in care can be identified early.

Growth Charts

• The CDC charts include children raised in a variety of nutritional conditions in the United States. In the CDC charts, the normal range between 5th and 95th percentiles. 
• The WHO growth chart describes children from birth to five years raised under optimal environmental conditions. The normal range is expressed as a Z score between -2.0 and +2.0, corresponding to 2 and 98 percentiles. Z-scores are the number of Standard deviations from the mean.
• The WHO growth charts represent a growth standard, whereas the CDC growth chart represents a growth reference. WHO growth charts are used for children under two years of age, and the CDC growth charts are used in children for more than two years. 
• When using the WHO charts, the prevalence of short stature and obesity is similar to the CDC charts, but the underweight prevalence was lower than the CDC charts. [15] [16]
• Preterm infants 
• During the stay in the neonatal intensive care unit, preterm growth charts like Fenton growth charts are used for all preterm infants less than 37 weeks gestational age. Fenton charts can be used from 22 weeks gestational age and up to ten weeks post-term.
• WHO charts are useful to monitor the growth of preterm infants less than 37 weeks after discharge. The corrected postnatal age is used for up to two years. Corrected age for preterm kids is calculated as actual age in weeks - (40 weeks - gestational age at birth in weeks). [17]

Developmental Screening 

Only 20% of the children with developmental delay in the United States receive early intervention before three years. Early intervention is useful in high-risk children to improve their cognitive and academic performance. Less than 50 % of clinicians are only using standardized screening tools in practice. Time constraints, lack of training are essential barriers in using the developmental screening tool. The Ages and Stages Questionnaire (ASQ), the Parents' Evaluation of Developmental Status, and the Child Development Inventory are standard screening tools used in practice. ASQ tool can be used for up to 66 months. The PEDS tool can be used up to eight years of age.  Gross and fine motor milestones are assessed at every well-child visit in the first four years. Standardized developmental assessments using ASQ are mandatory at 9, 18, and 24 or 30 months. [18]  

The clinician may screen more frequently if there are risk factors like prematurity, lead exposure, or low birth weight. Autism screening needs to be done at 18 and 24 months of age. If the screening tool reveals developmental delay, the child needs referrals to developmental pediatricians. Children up to three years with developmental delay are referred to early intervention programs, and children above three years of age are referred to special education services. 

Red Flags in Growth and Development 

• Red flag signs in motor development are persistent fisting for more than three months, the persistence of primitive reflexes and rolling before two months, and hand dominance before 18 months. 
• No babbling by twelve months, no single words by sixteen months, no two-word sentences by two years, and loss of language skills are red flags.
• Children whose height or weight readings below the 5th percentile, above the 95th percentile, or cross two major centile lines need further evaluation.
• Enhancing Healthcare Team Outcomes

The health care team should understand the developmental stages that their patients go through during early childhood. We should increase the awareness of health care professionals about the importance of standardized growth monitoring and the appropriate use of growth charts. Also, they need adequate training for using standard developmental screening tools.

Every clinician and nurse managing pediatric patients should have appropriate awareness of referral service to early intervention for eligible patients. Interprofessional collaboration between clinicians, mid-level practitioners, and nurses can improve patient outcomes as developmental delays require prompt intervention when caught, and earlier is always better. Children up to three years with developmental delay are referred to early intervention programs, and children above three years of age are referred to special education services.

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Disclosure: Palanikumar Balasundaram declares no relevant financial relationships with ineligible companies.

Disclosure: Indirapriya Darshini Avulakunta declares no relevant financial relationships with ineligible companies.

This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal.

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By Emily Leclerc | Waisman Science Writer

*Note: The Travers lab has chosen to use identity first language in response to the growing preference for this type of language in the autism community. The language in this story reflects that choice.*

Autism is often associated with complex tasks like social processing and language and the later-developing brain regions that control them. But what if autism is more rooted in the earliest developing and most reflex-like part of the brain – the brainstem? This brainstem focused hypothesis about autism was put forth nearly 60 years ago by scientists but was left virtually untested due to the challenges of imaging the area in living individuals.

This new research by Brittany Travers, PhD , Waisman investigator and associate professor of kinesiology, is the first to officially test this hypothesis in children thanks to the advancements in brain imaging techniques. Her work reveals that the brainstem may indeed be central to core autism features. “It is a pivotal brain structure and deserves some attention, particularly in autism,” Travers says.

A stalk-like structure located at the base of the brain, the brainstem controls the body’s involuntary and automatic processes such as heart rate, blood pressure, breathing, digestion, and swallowing, among other functions. Even though we may not be aware of it, this autonomic nervous system – the name given to the specific bundle of nerves in the brainstem that regulate those processes – is in a constant state of responding to external and internal information.

The brainstem has reactions and sets of reactions to a variety of stimuli to try to keep our body in a state of balance, or homeostasis. Increase heart rate when this happens. Lower blood pressure when that happens. Disrupt digestion to reallocate energy when this happens. In turn, our behavior may be subtly or not so subtly affected by the underlying autonomic nervous system processing, even if we are not aware of it. So, what happens when this system is acting differently in a person?

“The brainstem is one of the earliest developing parts of the brain. So, it makes sense, in a neurodevelopmental condition like autism, that there would be differences that are happening in the brainstem that help explain the individual differences in autism,” Travers says.

Travers’ recent paper, “ Role of autonomic, nociceptive, and limbic brainstem nuclei in core autism features ” published in the journal Autism Research , shows that several core autism features, such as social communication differences and restrictive or repetitive behavior, may be directly related to the areas of the brainstem involved in autonomic functions, which may lead autistic individuals to experience or interpret the world’s stimuli in different ways.

Travers and her team utilized diffusion tensor imaging (DTI), a type of magnetic resonance imaging (MRI) that specifically measures how water diffuses through different tissue types, to look at the brainstem’s structure in autistic individuals and non-autistic individuals. Traditionally, the brainstem is a hard structure to image due to its location and the similarities in its tissue composition. DTI makes it possible to visualize the brainstem’s unique structure and tissue composition. Travers found differences in the autonomic nervous system’s structure between the two groups of participants that correlated with social communication differences and more restrictive or repetitive behavior.

DTI allowed Travers to focus specifically on the nuclei in the brainstem that are involved in our autonomic functions, pain systems, and the limbic system – which handles memory, emotion, and stress responses. “The autonomic nervous system is very much tied to the pain network and also to emotional structures. The original theories were also in line with these parts of the brainstem,” Travers says. “So, we chose to look at this particular grouping of brainstem structures.”

In particular, Travers found two nuclei in the brainstem that showed microstructural differences in autistic individuals and significant association with core autism features. The first nucleus, LPB, is involved in the pain processing system for internal organs and showed a significant relationship with an increase in repetitive behaviors. The second nucleus, PCRtA, is involved in digestion, swallowing, eating, and cardio-respiration and showed a meaningful relationship with more pronounced social communication challenges. Travers hypothesizes that structural changes in PCRtA could contribute to why it is fairly common for autistic individuals to have gastrointestinal discomfort and struggles eating or swallowing.

“This study was the first to be able to test this 60-year-old hypothesis in living children, and found that specific areas within the brainstem are linked to autism features,” Travers says. “This study directly tests and confirms this prior theory while also extending the literature to show that it is not all of the brainstem but some very specific nuclei that are involved in autonomic processing.”

Even the oldest and most rudimentary part of the brain still presents with great complexity. This work indicates that the brainstem likely plays an important role in the core features of autism but the mechanisms behind it are still a mystery. The study’s results did not reveal to Travers what exact changes to the brainstem are contributing to the core features. “We don’t know from our DTI if it is the myelination or the number of neurons or something else because we’re only looking at how water interacted with the tissues. This study helps us locate differences within the brainstem, but It brings up more questions than it solves,” Travers says. She hopes to answer those questions in future research.

“The brainstem is so important because it is this intersection between the brain and the rest of the body. So much information is transmitted through the brainstem and yet we’ve omitted it from most of our studies,” Travers says. “I’ve learned that the brainstem seems to be important in autism and it’s time that we really dug into this.”

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