Chapter 2: How We Grow - Developmental Psychology

Developmental Psychology is the study of the processes of change throughout the human lifespan. We don’t just get older; we mature through complex psychological stages.

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1. Theories of Personality and Social Development

(1) Freud’s Psychosexual Development Stages

Freud defined human mental energy as Libido and divided development stages based on where this energy is concentrated.

• Oral → Anal → Phallic → Latent → Genital
• He believed that if needs are not properly met at each stage, “fixation” can occur in adulthood.

(2) Erikson’s Psychosocial Development Stages

Expanding on Freud’s theory, Erikson proposed an 8-stage model spanning the entire life. Each stage involves a Psychosocial Crisis to be resolved.

• Infancy: Trust vs. Mistrust
• Adolescence: Identity vs. Role Confusion (The most critical stage)
• Early Adulthood: Intimacy vs. Isolation

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2. Development of Intelligence and Thought: Jean Piaget

Piaget observed that the way children understand the world is fundamentally different from that of adults.

Development Stage	Key Features	Core Concept
Sensorimotor	Exploring the world through senses/motor	Object Permanence
Preoperational	Beginning of language use, egocentrism	Symbolic Play
Concrete Operational	Beginning of logical thinking	Concept of Conservation
Formal Operational	Abstract and hypothetical thinking	Deductive Reasoning

Mechanisms of Knowledge Construction

• Assimilation: Fitting new information into existing frameworks (Schemas).
• Accommodation: Modifying existing frameworks to fit new information.

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3. Moral Development: Lawrence Kohlberg

Human moral judgment evolves from “Avoiding Punishment” to “Social Contract” and eventually to “Universal Ethical Principles.”

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Key Checklist

• In Erikson’s 8 stages, which period focuses on forming an identity and asking “Who am I?” (Answer: Adolescence)
• In Piaget’s theory, what is the process of taking in new information to fit existing cognitive structures? (Answer: Assimilation)
• What is the concept of understanding that the essential quantity of an object remains the same even if its appearance changes? (Answer: Conservation)

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