Explain theories of human development

What this dot point is asking

Nature versus nurture

A core debate asks whether development is driven mostly by genetics and maturation (nature) or by experience and environment (nurture). Most psychologists now take an interactionist view, that genes and environment work together. Twin and adoption studies are used to estimate the influence of each.

Cognitive development: Piaget

Jean Piaget proposed children actively build knowledge through schemas (mental frameworks), using assimilation (fitting new information into existing schemas) and accommodation (changing schemas to fit new information). He described four stages:

• Sensorimotor (0 to 2 years): learning through senses and movement; achieving object permanence.
• Preoperational (2 to 7 years): symbolic thinking but egocentrism and a lack of conservation.
• Concrete operational (7 to 11 years): logical thinking about concrete objects; conservation achieved.
• Formal operational (11 plus): abstract and hypothetical reasoning.

Piaget's conservation tasks showed young children think a taller glass holds more water even when the amount is unchanged. Critics argue he underestimated children's abilities. Lev Vygotsky offered an alternative, stressing social and cultural learning through the zone of proximal development and scaffolding by more knowledgeable others.

Attachment

John Bowlby argued attachment is an innate, evolutionary bond that aids survival, with a critical period in the early years. He proposed monotropy (a primary attachment figure) and an internal working model that shapes later relationships.

Mary Ainsworth's "Strange Situation" (1970) observed infants' reactions to separation and reunion with a caregiver, identifying attachment types: secure, insecure-avoidant and insecure-resistant. Secure attachment was linked to sensitive, responsive caregiving. Harlow's monkey studies (1958) showed infant monkeys preferred a soft cloth "mother" over a wire one that provided food, suggesting comfort matters more than feeding for attachment.

Psychosocial development: Erikson

Erik Erikson described eight stages across the whole lifespan, each with a conflict to resolve, such as trust versus mistrust in infancy, identity versus role confusion in adolescence, and integrity versus despair in old age. Successfully resolving each stage builds a healthy personality.

Moral development: Kohlberg

Lawrence Kohlberg studied moral reasoning using dilemmas such as the Heinz dilemma. He proposed three levels:

• Preconventional: morality based on rewards and punishment.
• Conventional: morality based on social approval and law.
• Postconventional: morality based on abstract ethical principles.

Evaluating developmental theories

No single theory captures development. Piaget mapped how thinking changes but underestimated children and downplayed culture; Vygotsky corrected this by stressing social learning. Bowlby's attachment theory is supported by Ainsworth and Harlow but the idea of a fixed critical period is now softened to a more flexible sensitive period. Erikson extended development across the whole lifespan, which fits modern views, though his stages are hard to test precisely. Kohlberg's moral stages were criticised for being based mainly on male samples and for valuing abstract justice over care. A strong TASC answer names the theory, its supporting evidence and a limitation, then notes that the theories are complementary rather than competing.

Putting it together

When the exam describes a child or a developmental change, first identify the domain (cognitive, attachment, psychosocial or moral) and the matching theorist, then apply the specific stage or concept and, where the question asks, evaluate it. These theories help explain how thinking, relationships, identity and morality develop, and they link directly to wellbeing across the lifespan and to the nature versus nurture debate that runs through the whole course.