Psychology › Development & attachment
Child development and how thinking grows
· Concept
Well replicatedStrong, repeated evidence.
How babies who cannot speak become children who reason, talk, plan and understand other minds.
See it on the Psychology map →What it says
Developmental psychology tracks how thinking grows. Jean Piaget saw children as little scientists passing through fixed stages; Lev Vygotsky stressed learning with adults and peers. From the 1980s, experiments timing how long babies stare at surprising events showed that infants of a few months expect hidden objects to keep existing, earlier than Piaget thought. By about four, children grasp that others can hold false beliefs. The brain reaches roughly 90% of adult size by age six.
Why it matters
It shapes schooling, parenting advice and early-childhood policy. Michigan's small Perry Preschool program, begun in 1962 and tracked for decades, is widely cited for long-term payoffs in earnings and lower crime.
The evidence
Status: well replicated for the broad milestones. Lab experiments across many cultures, plus long cohort studies that follow children from birth, such as New Zealand's Dunedin study, begun in 1972.
Open questions
How much infants know from birth versus learn very fast, and how fully later experiences can make up for a poor start.
Inside this (3)
Connections (3)
▸Jean Piaget's stages of cognitive development are the classic theory of Child development and how thinking growsMixed evidence
The connection
Piaget made the growth of thinking itself the core question of child development. He argued that children actively build knowledge, like little scientists, and that their errors follow age-linked patterns, which he grouped into four stages. For decades his tasks set the research agenda, and most later theories of child thinking, including Vygotsky's, define themselves against his.
Who showed it and when
Geneva, Switzerland, from the 1920s, built partly on watching his own three children; key books appeared from 1936 into the 1970s.
How solid is it?
His tasks still work as he described, but newer methods show many abilities appear earlier and less stage-like than he claimed, hence the mixed rating.
Open questions
Whether any single grand theory can replace his: newer accounts, such as core knowledge and information processing, explain specific findings better but offer no equally broad map.
▸Lev Vygotsky and the zone of proximal development stressed social learning in Child development and how thinking growsMixed evidence
The connection
Vygotsky moved the focus from the child working alone to the child learning with others. He argued that what a child can do with help reveals where development is heading, and that adults and peers pull it forward through talk and shared tasks. Even children's self-talk ('private speech'), he said, is conversation turning inward.
Who showed it and when
Developed in Moscow in the early 1930s; spread in the West after Mind in Society (1978). The term 'scaffolding' came from Wood, Bruner and Ross in 1976.
How solid is it?
Studies show children use more private speech on harder tasks and often do better when they do; tutoring research supports guided help, though the zone itself is hard to measure.
Open questions
How to measure a child's zone precisely, and whether the idea adds much beyond the principle that good teaching meets learners where they are.
▸Theory of mind (the false-belief test) emerges around age four in Child development and how thinking growsWell replicated
The connection
Around age four, most children grasp that other people can hold false beliefs. In the classic test, three-year-olds usually say Maxi will look for his chocolate where it was moved while he was out; five-year-olds say where he left it. This milestone opens the way to keeping secrets, telling white lies and seeing other viewpoints.
Who showed it and when
Heinz Wimmer and Josef Perner, University of Salzburg, Austria, 1983; Simon Baron-Cohen, Alan Leslie and Uta Frith's 'Sally–Anne' version followed in London in 1985.
The evidence
Beyond the 2001 meta-analysis, Wellman and Liu's 2004 scale of five tasks found false belief arrives in a steady order, after children grasp that people can want, think and know different things.
Open questions
Why timing varies: children with siblings, or with parents who often talk about feelings, tend to pass earlier; deaf children of hearing parents often pass later.