Developmental Psychology

Jean Piaget proposed that children progress through four universal stages of cognitive development: sensorimotor (0-2 years), preoperational (2-7), concrete operational (7-11), and formal operational (11+). Each stage represents a qualitatively different way of thinking about the world.

Developed by John Bowlby and Mary Ainsworth, attachment theory holds that infants form emotional bonds with primary caregivers that serve as a secure base for exploration. The quality of this attachment (secure, anxious-avoidant, anxious-resistant, or disorganized) shapes social and emotional development across the lifespan.

Erik Erikson proposed eight stages of psychosocial development spanning the entire lifespan. Each stage presents a central conflict (e.g., trust vs. mistrust, identity vs. role confusion) that must be resolved for healthy psychological growth.

Lev Vygotsky's concept describing the gap between what a learner can do independently and what they can achieve with guidance from a more skilled partner. Learning is most effective when instruction targets this zone through scaffolding.

The longstanding debate over the relative contributions of genetic inheritance (nature) and environmental factors (nurture) to human development. Modern developmental psychology recognizes that genes and environment interact dynamically through processes like epigenetics and gene-environment correlation.

Critical periods are specific time windows during which certain experiences are essential for normal development, and their absence causes permanent deficits. Sensitive periods are broader windows during which the organism is especially responsive to environmental input but can still develop the ability later with more effort.

The cognitive ability to attribute mental states (beliefs, desires, intentions, knowledge) to oneself and others, and to understand that others may hold beliefs different from one's own. This capacity typically emerges around age 4-5 and is central to social cognition.

Lawrence Kohlberg proposed six stages of moral reasoning grouped into three levels: preconventional (self-interest), conventional (social conformity), and postconventional (universal ethical principles). People progress through these stages in a fixed order, though not everyone reaches the highest stages.

A teaching strategy in which a more knowledgeable person provides structured support to help a learner accomplish a task within their zone of proximal development, then gradually withdraws that support as the learner gains competence.

The brain's ability to reorganize itself by forming new neural connections throughout life. While neuroplasticity is greatest during early development, the brain retains significant capacity for change in response to learning, experience, and injury across the lifespan.