Introduction to Developmental Theories

Learning Objectives

At the end of this lesson, you will be able to:

  1. Define theory.
  2. Describe Freud’s theory of psychosexual development.
  3. Identify the parts of the self in Freud’s model.
  4. List five defense mechanisms.
  5. Describe five defense mechanisms.
  6. Appraise the strengths and weaknesses of Freud’s theory.
  7. List Erikson’s eight stages of psychosocial development.
  8. Apply Erikson’s stages to examples of people in various stages of the lifespan.
  9. Appraise the strengths and weaknesses of Erikson’s theory of psychosocial development.
  10. Compare and contrast Freud and Erikson’s theories of human development.
  11. Describe the principles of classical conditioning.
  12. Identify unconditioned stimulus, conditioned stimulus, unconditioned response, and conditioned response in  classical conditioning.
  13. Describe the principles of operant conditioning.
  14. Identify positive and negative reinforcement, and primary and secondary reinforcement.
  15. Contrast reinforcement and punishment.
  16. Contrast classical and operant conditioning and the kinds of behaviors learned in each.
  17. Describe social learning theory.
  18. Describe Piaget’s theory of cognitive development.
  19. Define schema, assimilation, accommodation, and cognitive equilibrium.
  20. List Piaget’s stages of cognitive development.
  21. Describe Piaget’s stages of cognitive development.
  22. Critique Piaget’s theory of cognitive development.
  23. Describe Vygotsky’s sociocultural theory of cognitive development.
  24. Explain what is meant by the zone of proximal development.
  25. Explain guided participation.
  26. Describe scaffolding.
  27. Compare Piaget and Vygotsky’s models of cognitive development.
  28. Describe Bronfenbrenner’s ecological systems model.

What is a theory?

Students sometimes feel intimidated by theory; even the phrase, “Now we are going to look at some theories…” is met with blank stares and other indications that the audience is now lost. But theories are valuable tools for understanding human behavior; if fact they are proposed explanations for the “how” and “whys” of development. Have you ever wondered, “Why is my 3 year old so inquisitive?” or “Why are some fifth graders rejected by their classmates?” Theories can help explain these and other occurrences. Developmental theories offer explanations about how we develop, why we change over time and the kinds of influences that impact 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.


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.

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

Erikson, E. H. (1968). Identity, youth, and crisis. New York: Norton.

O’Grady, D. & Metz, J. (1987). Resilience in children at high risk for psychological disorder. Journal of Pediatric Psychology 12(1):3-23.

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


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Developmental Psychology Copyright © 2022 by Bill Pelz and Lumen Learning is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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