3.1 Theories of Development

Piaget's Cognitive Development

Piaget proposed children move through four stages: sensorimotor (birth–2, object permanence), preoperational (2–7, symbolic thought, egocentrism, lacks conservation), concrete operational (7–11, conservation, logical thinking about concrete objects), and formal operational (12+, abstract reasoning). Development occurs through schemas, assimilation, and accommodation as children adapt to new information.

Erikson's Psychosocial Stages

Erikson described 8 psychosocial stages across the lifespan, each with a crisis to resolve, such as trust vs. mistrust (infancy), identity vs. role confusion (adolescence), and integrity vs. despair (late adulthood). Successfully resolving each stage builds healthy personality development; failure can create lasting struggles.

Vygotsky & Kohlberg

Vygotsky emphasized the social and cultural context of learning, introducing the zone of proximal development (ZPD)—tasks a child can do with guidance but not alone—and scaffolding to support learning. Kohlberg proposed stages of moral development: preconventional (self-interest), conventional (social rules), and postconventional (abstract ethical principles).

Key terms

Piaget's Stages

Sensorimotor, preoperational, concrete operational, formal operational — stages of cognitive development.

Object permanence

Understanding that objects continue to exist even when not seen; develops in the sensorimotor stage.

Zone of proximal development (ZPD)

Vygotsky's term for the gap between what a learner can do alone vs. with guided assistance.

Erikson's psychosocial stages

8 stages across the lifespan, each involving a crisis (e.g., trust vs. mistrust, identity vs. role confusion).

Kohlberg's moral development levels

Preconventional (self-interest), conventional (social rules), postconventional (abstract ethical principles).

Try an AP-style question

A longitudinal study follows…

1. different age groups at once
2. animals only
3. one person in depth
4. the same people over time