Developmental Psychology: Change Across the Lifespan
Core concepts
Developmental psychology examines physical, cognitive and social change across the lifespan. Know Piaget's stages (sensorimotor, preoperational, concrete operational, formal operational) with key achievements: object permanence, conservation, egocentrism, abstract reasoning. Understand criticisms: underestimating children's abilities, vague stage boundaries, and cultural variation.
Know Vygotsky's sociocultural theory: zone of proximal development, scaffolding, and language as a tool of thought. Understand attachment (Bowlby's monotropic theory, Ainsworth's Strange Situation: secure, insecure-avoidant, insecure-resistant, disorganised), and the role of sensitive responsiveness. Know parenting styles (authoritative, authoritarian, permissive, neglectful) and Erikson's psychosocial stages at a general level.
Common traps
- Saying a preoperational child cannot conserve because they are "not intelligent"; the explanation is centration and inability to reverse operations.
- Confusing attachment type with attachment quality or with temperament.
- Presenting Piaget's ages as fixed cut-offs; they are approximate.
- Mixing cross-sectional (different ages at one time) with longitudinal (same participants over time) designs and their confounds.
Rule of thumb
For any developmental claim, ask: is this describing a normative pattern (typical sequence) or individual differences (variation between children)? Evaluation should address both.
Worked example
A four-year-old insists a tall thin glass holds more water than a short wide one containing the same volume. This demonstrates failure of conservation, explained by centration on height and inability to mentally reverse the pouring.