Charles Darwin is credited with conducting the first systematic study of developmental psychology. In 1877 he published a short paper detailing the development of innate forms of communication based on scientific observations of his infant son, Doddy. However, it was the 1900s that saw two key psychologists - Jean Piaget (1896-1980) and Lev Vygotsky (1896-1934, – develop theories that have heavily influenced our understanding of how children grow up and learn to understand the world around them.
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 intellectual development as a process of biological development and interaction with the world.
He became interested in the way that fundamental concepts like the very idea of number, time, quantity, causality, justice, and so on emerged. Piaget showed that young children think in strikingly different ways compared to adults.
According to Piaget, children are born with a very basic mental structure (genetically inherited and evolved) on which all subsequent learning and knowledge are based. The goal of his theory is to explain the mechanisms and processes by which the infant, and then the child, develops into an individual who can reason and think using hypotheses. Children construct an understanding of the world around them, then experience discrepancies between what they already know and what they discover in their environment.
Imagine what it would be like if you did not have a mental model of your world. It would mean that you would not be able to make so much use of information from your past experience or to plan future actions.
Schemas are the basic building blocks of such cognitive models, and enable us to form a mental representation of the world. Piaget called the schema the basic building block of intelligent behaviour – a way of organizing knowledge. Indeed, it is useful to think of schemas as “units” of knowledge, each relating to one aspect of the world, including objects, actions, and abstract (i.e., theoretical) concepts. Think of schemata (the plural of schema) as 'index cards' filed in the brain, each one telling an individual how to react to incoming stimuli or information.
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.
For example, a person might have a schema about buying a meal in a restaurant. The schema is a stored form of the pattern of behaviour that includes looking at a menu, ordering food, eating it and paying the bill. This is an example of a type of schema called a 'script.' Whenever they are in a restaurant, they retrieve this schema from memory and apply it to the situation.
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. When faced with new objects or new situations, the brain searches its existing schemas and finds the best match. We then absorb this situation into our existing schemata (assimilation) or adapt the schemata as required (accommodation). New situations can be very disconcerting, as they don’t fit existing schemata. This causes a state of disequilibrium. Equilibration is the force which drives the learning process as we do not like to be frustrated and will seek to restore balance by mastering the new challenge (accommodation). Piaget theorises that we make progress is leaps and bounds, rather than on a steady trajectory.