Major Theories of Human Development — Summary of Chapter 2 from The Developing Person Through the Life Span

How do we explain human growth, personality, and behavior across the lifespan? Chapter 2 of Kathleen Stassen Berger’s The Developing Person Through the Life Span introduces students to the most influential developmental theories in psychology. This chapter breaks down how leading thinkers like Freud, Erikson, Piaget, Vygotsky, and Skinner interpreted the complex journey of human development.

Watch the video above for an audio summary of each theory, or read below for a structured guide to the foundational ideas shaping developmental psychology.

Psychodynamic Theory: Freud and Erikson

Sigmund Freud proposed that development occurs through a series of psychosexual stages, where unconscious desires and conflicts shape personality. Each stage focuses on different erogenous zones and unresolved conflicts that influence adult behavior.

Erik Erikson extended Freud’s ideas with his psychosocial theory, identifying eight developmental stages from infancy to old age. Each stage presents a crisis that must be resolved for healthy psychological growth, such as trust vs. mistrust or identity vs. role confusion.

Behaviorism: Learning Through Experience

Behaviorism focuses on observable behaviors and emphasizes the role of the environment. Key figures include:

• Ivan Pavlov: Introduced classical conditioning, where individuals learn by associating stimuli.
• John Watson: Argued that psychology should focus solely on behavior, not internal thoughts.
• B.F. Skinner: Developed operant conditioning, highlighting reinforcement and punishment as tools for shaping behavior.
• Albert Bandura: Introduced social learning theory and modeling, where behavior is learned by observing others.

Cognitive Theory: Understanding Thought Development

Jean Piaget emphasized how children think differently at various stages. His cognitive theory identifies four stages of cognitive development:

• Sensorimotor
• Preoperational
• Concrete operational
• Formal operational

He introduced terms like assimilation (adding new info to existing ideas) and accommodation (altering existing frameworks to fit new info), emphasizing the need for cognitive equilibrium.

The information-processing theory builds on Piaget’s work by likening the human mind to a computer—input, storage, and output of information are central to learning and memory development.

Sociocultural and Evolutionary Theories

Lev Vygotsky developed sociocultural theory, highlighting how culture, social interaction, and mentorship drive development. Key concepts include:

• Guided participation: Learning through support from knowledgeable individuals
• Zone of proximal development (ZPD): The gap between what a learner can do alone and what they can do with help

The evolutionary theory, grounded in Darwinian principles, suggests that certain psychological traits and behaviors persist because they enhance survival and reproduction. This theory introduces the idea of selective adaptation—how inherited behaviors benefit individuals in specific environments.

The Eclectic Perspective

Because no single theory can explain every aspect of human development, many psychologists adopt an eclectic perspective. This approach integrates elements from multiple theories, offering a more flexible and holistic understanding of development.

Glossary of Key Terms from Chapter 2

• Accommodation: Altering old concepts to fit new experiences
• Assimilation: Integrating new information into existing cognitive structures
• Behaviorism: The study of observable behavior shaped by learning
• Classical conditioning: Associating a neutral stimulus with a meaningful one
• Operant conditioning: Learning based on consequences like reinforcement or punishment
• Modeling: Learning behaviors by observing others
• Social learning theory: Emphasizes observation and imitation in learning
• Information-processing theory: Views human cognition as similar to computer functions
• Sociocultural theory: Stresses the role of social and cultural influences on development
• Zone of proximal development: Skills a learner can develop with guidance
• Evolutionary theory: Considers inherited traits that aid survival
• Selective adaptation: Inherited behaviors that enhance environmental fit
• Eclectic perspective: Integrates elements from various theories

Conclusion: Why These Theories Matter

Each theory discussed in Chapter 2 contributes to our understanding of human growth from a unique lens. Whether emphasizing unconscious drives, environmental reinforcements, or cultural influences, these frameworks allow us to better understand how and why people change. By adopting an eclectic perspective, students and professionals can draw on the strengths of each theory to address the complexities of real-world development.

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If you’re preparing for an exam or just want to understand the psychology of human growth, this chapter is a perfect starting point. Be sure to check out Chapter 1 if you haven’t already, and continue following along for future summaries in this series.

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