His contributions include a stage theory of child cognitive development, detailed observational studies of cognition in children, and a series of simple but ingenious tests to reveal different cognitive abilities.
What Piaget wanted to do was not to measure how well children could count, spell or solve problems as a way of grading their I. What he was more interested in was the way in which fundamental concepts like the very idea of number, time, quantity, causality, justice and so on emerged.
Piaget's (1936) theory of cognitive development explains how a child constructs a mental model of the world.
He disagreed with the idea that intelligence was a fixed trait, and regarded cognitive development as a process which occurs due to biological maturation and interaction with the environment.
When Piaget talked about the development of a person's mental processes, he was referring to increases in the number and complexity of the schemata that a person had learned.
When a child's existing schemas are capable of explaining what it can perceive around it, it is said to be in a state of equilibrium, i.e., a state of cognitive (i.e., mental) balance.A baby will suck a nipple, a comforter (dummy), or a person's finger.Piaget, therefore, assumed that the baby has a 'sucking schema.'Similarly, the grasping reflex which is elicited when something touches the palm of a baby's hand, or the rooting reflex, in which a baby will turn its head towards something which touches its cheek, are innate schemas.With this new knowledge, the boy was able to change his schema of “clown” and make this idea fit better to a standard concept of “clown”. Each child goes through the stages in the same order, and child development is determined by biological maturation and interaction with the environment.Although no stage can be missed out, there are individual differences in the rate at which children progress through stages, and some individuals may never attain the later stages.Piaget was employed at the Binet Institute in the 1920s, where his job was to develop French versions of questions on English intelligence tests.He became intrigued with the reasons children gave for their wrong answers to the questions that required logical thinking.The schemas Piaget described tend to be simpler than this - especially those used by infants.He described how - as a child gets older - his or her schemas become more numerous and elaborate.Shaking a rattle would be the combination of two schemas, grasping and shaking.A 2-year-old child sees a man who is bald on top of his head and has long frizzy hair on the sides.