Developmental Theories

Brindusa Vanta, MD, DHMHS
Medical editor

Ad Disclosure: Some of our recommendations, including BetterHelp, are also affiliates, and as such we may receive compensation from them if you choose to purchase products or services through the links provided

What is Developmental Theory?

Developmental theory refers to the study of systematic changes in individuals across their lifespan, focusing on physical, cognitive, emotional, and social development from infancy through adulthood. It seeks to understand how individuals grow, adapt, and change over time, influenced by biological maturation, environmental factors, and interpersonal relationships.[1]

Understanding developmental stages is significant, as it provides insights into typical patterns of growth and behavior at different ages, guides interventions and support strategies, and promotes optimal development across an individual's lifespan.[1] It helps identify age-appropriate expectations, recognize developmental milestones, and address potential challenges or delays early on, enhancing individual well-being and fostering healthy relationships and communities.

Developmental theories present systematic ways of thinking about how human beings grow from babies to adolescents to adults to elderly people and the various changes they undergo as they make this passage. Various developmental theories describe different types of changes. For instance, Jean Piaget's influential theories describe how an individual's intellectual development evolves. Lawrence Kohlberg’s theories describe moral evolution over time as people grow. Eric Erikson and Robert Kegan have created theories that describe how identity and the nature of the self-change with increasing maturity. 


Though progress toward development is happening all the time, the changes that occur are generally gradual in nature. It's only over long periods that clear progress from one state to another is apparent. For this reason, developmental theorists tend to view development in terms of stages that people pass through. Each stage is often marked by the attainment of a milestone event (such as learning to have object permanence, to walk and talk, or to take responsibility for one's actions).

Key Theorists and Their Contributions

Many different theorists have contributed developmental theories and models that are key to understanding lifespan development. 

Jean Piaget: Cognitive Development

Therapists are Standing By to Treat Your Depression, Anxiety or Other Mental Health Needs

Explore Your Options Today


Piaget's theory of cognitive development emphasizes how children actively construct knowledge through interactions with their environment. According to Piaget, children progress through distinct stages of cognitive development, including sensorimotor, preoperational, concrete operational, and formal operational stages, each characterized by unique ways of thinking and understanding the world.[2]

Lawrence Kohlberg: Moral Development

Kohlberg's theory of moral development posits that individuals progress through a series of moral stages, each representing increasingly complex understandings of moral reasoning and ethical dilemmas. He identified three main levels of moral development: pre-conventional, conventional, and post-conventional, with each level consisting of two stages.[3]

Erik Erikson: Psychosocial Development

Erikson's psychosocial theory emphasizes the importance of social interactions and cultural influences in shaping an individual's development across their lifespan. He proposed eight stages of psychosocial development, each characterized by a unique psychosocial crisis or conflict that individuals must resolve to achieve healthy personality development.[4]

Lev Vygotsky: Sociocultural Approach

Vygotsky's sociocultural theory emphasizes the role of social interactions, cultural context, and language in cognitive development. He proposed that learning occurs through social collaboration and scaffolding, where more knowledgeable individuals provide support and guidance to learners, facilitating their cognitive growth.[5]

As Dr. Brindusa Vanta, MD, says, "Vygotsky introduced an important concept known as the zone of proximal development. This refers to the gap between learners' independent capabilities and what they can achieve with assistance. Recognizing this gap is essential for promoting cognitive growth and offers appropriate levels of support."

Cognitive Development: Stages and Milestones

In general, developmental theories view development as progress from simple to more complex understandings of the self and the world over time. Progress may be continuous in nature or occur in stages, but the momentum is almost always forward toward greater, more complex understandings. For example, prior to achieving object permanency, babies don't understand that objects (toys, people) continue to exist even when out of sight. Instead of looking for a toy hidden under a blanket, they quickly lose interest in the toy as though it never existed. As they grow, babies come to master the idea of object permanency and will begin looking for objects hidden from their view. According to developmental theories, learning to see the world in increasingly complicated ways continues to occur throughout a child's lifespan.

Piaget’s theory of cognitive development discusses these stages in more detail as they relate to learning, problem-solving, and cognitive milestones in children and adolescents. Here’s an overview:[6]

  • Sensorimotor stage (birth to 2 years): Infants explore the world through their senses and motor actions. This is when object permanence develops, allowing infants to understand that objects continue to exist even when they're out of sight.
  • Preoperational stage (2 to 7 years): Children engage in symbolic play and develop language skills. For example, a child may engage in animistic thinking, attributing human characteristics to inanimate objects like their trucks or cars.
  • Concrete operational stage (7 to 11 years): Children understand conservation and can perform mental operations on concrete objects. For example, a child may be able to understand that the amount of liquid remains the same even when poured into different-shaped containers.
  • Formal operational stage (11 years and older): Adolescents develop abstract thinking and hypothetical reasoning skills. These may include deductive reasoning and problem-solving tasks that involve considering multiple variables.

Cognitive development provides the foundation for learning and problem-solving by shaping an individual's ability to perceive, interpret, and organize information.[1]. As children and adolescents progress through Piaget's stages, they acquire increasingly sophisticated cognitive skills that enable them to engage in more complex learning tasks and problem-solving activities. For example, as children develop conservation skills during the concrete operational stage, they can apply these concepts to mathematical problems and scientific experiments, enhancing their ability to understand and manipulate abstract concepts.

Cognitive milestones in children and adolescents include the development of language, memory, attention, executive function, and metacognitive skills.[1] Key milestones include the emergence of symbolic play during the preoperational stage, the ability to understand cause-and-effect relationships during the concrete operational stage, and the capacity for abstract thinking and hypothetical reasoning during the formal operational stage. 

Monitoring cognitive milestones can help educators and caregivers assess children's progress, identify potential areas of difficulty, and provide appropriate support and interventions. However, it’s also important to acknowledge the broad spectrum of development that children fall on and not to overemphasize milestones rigidly.

As Dr. Brindusa Vanta, MD, says, "Piaget's theory of cognitive development is a valuable resource for teachers and parents, not only for psychologists. Teachers can use it to create teaching methods aligned with children's age-specific needs. Parents can adjust their interactions with their children based on their abilities."

Moral and Ethical Development: Kohlberg’s Theory

Kohlberg’s theory, instead of focusing on typical developmental milestones, focuses on moral stages of development. Here’s an overview of his moral development stages.

Pre-Conventional Level

  • Stage 1: Obedience and punishment orientation, in which individuals obey rules, avoid punishment, and seek rewards.
  • Stage 2: Individualism and exchange, in which people recognize that there are different perspectives and interests and behave in ways that satisfy their own needs.

Conventional Level

  • Interpersonal relationships: People value approval from others and maintain positive relationships by conforming to societal norms.
  • Maintaining social order: Individuals uphold laws and societal rules to ensure stability and social order.

Post-Conventional Level

  • Social contract and individual rights: People recognize the importance of social contracts and laws but understand that these can be changed for the greater good.
  • Universal principles: Individuals adhere to universal ethical principles based on justice, equality, and human rights.

These stages represent progressive levels of moral reasoning and ethical decision-making, where individuals move from self-interest and obedience to universal principles of justice and human dignity. It's important to note that people may not reach higher stages of moral development, and moral reasoning can vary depending on cultural, societal, and personal factors.

Application in Educational and Parenting Strategies

Kohlberg's stages of moral development can be applied in educational and parenting strategies, as they emphasize moral reasoning and ethical decision-making skills in children and adolescents.[7]

Strategies may include promoting open dialogue about moral dilemmas, encouraging perspective-taking and empathy, modeling ethical behavior, and providing opportunities for students to engage in moral reasoning and reflection.[8]

Additionally, educators and parents can create environments that support the development of moral autonomy and encourage students to consider the broader implications of their actions on others and society.   

Sensitive Periods and Development 

Due to a phenomenon known as sensitive periods, some development can only take place during certain times of life. When development is interrupted during a sensitive period, the normal development that occurs at that time does not occur.

Efforts to resume the development of affected skills or capabilities after the sensitive period has ended may meet with partial success, but it won't typically fully recover what has been lost. It's easier for young children to learn languages than for older children, for instance.

Progress through the developmental stages cannot be forced; instead, it needs to occur at its own pace. This is particularly true when speaking about early development because certain complex mental achievements can't occur until physical brain development has achieved a certain maturity (brain development continues to evolve long after birth!). Attempts to force a person to achieve a particular developmental stage or state before they are ready will typically fail.

Development progresses at its own pace, but it can easily become delayed or disrupted. Challenges can affect progress, leading to serious consequences. Success at each stage is dependent on earlier achievements; therefore, delays can have lasting impacts.

Not all people grow and change at the same rate. Even within a given person, growth can be uneven. A person may grow intellectually into a scholar but become developmentally delayed with regard to emotional maturity and fail to develop the emotional intelligence typical of their peers. This sort of domain-specific developmental delay may occur for any number of reasons, including abuse, drug or alcohol addiction, or even the individual's overwhelmed reaction to parental conflicts or divorce. 

Whatever the cause, developmentally delayed emotional immaturity can be expected to make that person's life more difficult than it might otherwise have been (filled with loneliness and difficulty forming and maintaining satisfying intimate relationships). In extreme cases, severe developmental delays can result in clinically significant disorders, including mental retardation (when intellectual functioning is severely delayed), certain personality disorders (when emotional coping and maturity are severely delayed), or anger and emotional control problems.

The key insights to take from developmental theories are that:

  1. Development is best understood as progress through an ordered series of increasingly complex progressive stages;
  2. Early developmental delays (interrupting progress towards a particular stage) threaten the developing person's overall progress; and 
  3. Uneven or incomplete development in any important life domain can lead to serious life problems.

It's important to identify and correct developmental delays while they are first occurring and as soon as possible to minimize the cumulative damage that delays may cause.

Additional Resources

As advocates of mental health and wellness, we take great pride in educating our readers on the various online therapy providers available. MentalHelp has partnered with several thought leaders in the mental health and wellness space, so we can help you make informed decisions on your wellness journey. MentalHelp may receive marketing compensation from these companies should you choose to use their services.

MentalHelp may receive marketing compensation from the above-listed companies should you choose to use their services.


  1. Santrock, J. W. (2019). Life-Span Development (17th ed.). McGraw-Hill Education.
  2. Erikson, E. H. (1950). Childhood and society. New York: W.W. Norton & Company.
  3. Kohlberg, L. (1969). Stage and sequence: The cognitive-developmental approach to socialization. In D. A. Goslin (Ed.), Handbook of socialization theory and research (pp. 347-480). Rand McNally.
  4. Piaget, J. (1952). The origins of intelligence in children. New York: International Universities Press.
  5. Vygotsky, L. S. (1978). Mind in society: The development of higher psychological processes. Harvard University Press.
  6. Piaget, J. (1954). The construction of reality in the child. New York: Basic Books.
  7. Kohlberg, L. (1984). The Psychology of Moral Development: The Nature and Validity of Moral Stages. Harper & Row.
  8. Berkowitz, M. W., & Gibbs, J. C. (1983). The Psychology of Character Development: The Moral Domain. Quorum Books.

Additional Resources

As advocates of mental health and wellness, we take great pride in educating our readers on the various online therapy providers available. MentalHelp has partnered with several thought leaders in the mental health and wellness space, so we can help you make informed decisions on your wellness journey. MentalHelp may receive marketing compensation from these companies should you choose to use their services.

MentalHelp may receive marketing compensation from the above-listed companies should you choose to use their services.