Developmental Psychology 101: Theories, Stages, & Research

Developmental psychology stagesDevelopmental psychology looks at how we grow and change in our thoughts and behaviors.

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.

What Is Developmental Psychology?

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).

4 Popular Theories, Stages, & Models

Developmental Psychology TheoriesThe key figures in the history of developmental psychology are predominantly known for their own theories and models.

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).

2 Questions and Research Topics

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).

Fascinating Case Studies & Research Findings

Developmental psychology has included many fascinating case studies and research findings. Here are two that we found particularly interesting.

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).

This case study illustrates the importance of inheritance and genes in the development of emotions and behaviors in children.

A Look at Positive Developmental Psychology

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.

Applying Developmental Psychology in Education

Developmental Psychology in EducationThe theory and findings we have shown you from developmental psychology have implications in real life.

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.

Five applications of developmental psychology in education
Principle 1: Teacher’s response:
Students who believe that intelligence is fixed are unlikely to take on challenging tasks and are vulnerable to negative feedback. Teachers should encourage children to understand that intelligence is malleable and promote a growth mindset.
Principle 2: Teacher’s response:
Cognitive development and learning are not limited by general stages of development. Developmental psychology stage theories do not fit well for all students. This does not mean the student has failed, and teachers should make this known to students.
Principle 3: Teacher’s response:
Emotional learning and self-regulatory skills can be learned by students. Students should be supported to control their emotions and behavior to enhance learning. This means using attention, organization, memory strategies, and planning.
Principle 4: Teacher’s response:
Creativity can be fostered in students. Creative thinking can be developed and nurtured by teachers by using innovative approaches to learning. Teachers should emphasize diverse perspectives and methods to foster creativity.
Principle 5: Teacher’s response:
Emotional wellbeing is vital in learning, performance, and development. Teachers should use emotional vocabulary, teach emotional regulation strategies, promote emotional understanding of others, and encourage all students.

Resources From

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.

A Take-Home Message

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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