Human Development
This domain tests lifespan development, stage theories, and the heredity–environment interaction.
Core frameworks
Development is multidimensional (physical, cognitive, social, emotional, moral) and lifelong. Piaget proposed four stages: sensorimotor (0–2; object permanence), preoperational (2–7; egocentrism, centration, failure of conservation), concrete operational (7–11; conservation, classification) and formal operational (11+; abstract, hypothetical reasoning). Schemas change by assimilation and accommodation. Vygotsky emphasised culture and the zone of proximal development (ZPD), with scaffolding by more able others. Kohlberg described preconventional, conventional and postconventional moral reasoning. Erikson framed psychosocial crises across the lifespan (trust versus mistrust, identity versus role confusion, and others). Bowlby and Ainsworth studied attachment; the strange situation classifies secure, avoidant and ambivalent patterns.
Worked example
A 5-year-old sees water poured from a wide glass into a tall thin glass and says there is now more water. This is preoperational thought: the child centres on height and fails conservation. The reasoning is stage-based, not a measure of intelligence.
Traps
Do not attribute conservation to the preoperational stage. The ZPD is Vygotsky, not Piaget. Concrete operational children solve problems about real objects; formal operational adolescents reason hypothetically. A correlation between parenting and child outcome does not prove that parenting caused it.