Jean Piaget

Jean Piaget's (1896 - 1980) theory of cognitive development during childhood was regarded as the typical example in which to understand the complex procedure of mental progression through different levels of thinking and understanding. One of the most important contributions that Piaget made was to establish the fact that the cognitive processes of young children are not simply immature versions of that of an adult, but that they have their very own rules. Although Piaget's theory has been widely challenged, his ideas still maintain a fundamental influence in both general psychology and existing education.

Piaget argued that cognitive development can be divided into four stages. Each stage is characterized by an overall structure and a sequence of development which occurs within this structure. According to Piagetian theory, these structures consist of "schemas", which are for all intents and purposes, ways of organizing experience; schemas are the primary component of intelligent behavior. These schemas adapt through a continuous process of "assimilation" and "accommodation," in an endeavor to attain "equilibrium" which is essentially balance. Assimilation is the process of adapting new experiences to fit into existing schemas whereas accommodation is the process of changing existing schemas to fit new experiences.

The first of Piaget's stages of cognitive development is the "sensorimotor stage". This stage occurs around zero to two years. It is in essence a stage of practical discovery, which occurs by interaction with the environment through the senses and by using motor skills. A baby accommodates and assimilates information which it encounters into schemas. Piaget contends that a baby is born with no sense of "object permanence". This is the understanding that objects continue to exist in their own right, when they are not being directly manipulated or immediately perceived. Piaget conducted an experiment to demonstrate the failure of object permanence on his daughter Jacqueline. This involved her trying to locate a rattle under a bed cover. He concluded from his observations of infants that it is during the first two years of a baby's life (during the sensorimotor stage) that it acquires object permanence (Piaget 1963).

The second of Piaget's stages is the "pre-operational stage". This stage lasts from around two to seven years. Piaget contended that at this time a child fails to "conserve". This is basically the understanding that things remain constant in terms of number, quantity and volume regardless of changes in appearance. In experiments to test number conservation, Piaget showed the child two sets of checkers which had exactly the same number of checkers in each set. He then re-arranged one of the sets, keeping the same amount of checkers in it, so that it was only different in appearance. In Piaget's findings the children in this stage of development believed that the sets were in fact of different quantity. Piaget argued that this occurred because the child is unable to conserve previous information. (Piaget 1952).

Within the pre-operational stage, Piaget identified a characteristic that he referred to as "egocentrism." This is the child's inability to see the world from another's perspective. They are quite literally self-centered. Piaget observed this phenomenon in his "Three mountains scene" experiment (Piaget & Inhelder, 1956). In this experiment the child was sat on one side of a model of three mountains, with a teddy sat at the opposite side. The child was asked to choose a picture which showed the scene that the teddy was able to see. Piaget discovered that until the age of seven, a child is unable to perceive a different viewpoint, from its own and is therefore said to be egocentric. Therefore, children do not realize when they have hurt someone else's feelings or why what they have done may be wrong. This also hinders a child's ability to communicate with others: A child will assume that the person she is talking to has the same perspective and knowledge that she does and will therefore leave out specific details that are needed in order to understand what the child is trying to say.

The next stage is the "concrete operations" stage which lasts from about age seven to eleven years. In this stage, children can perform operations requiring logic such as conservation. But this ability only holds for what he called concrete situations. That is, the child is only able to perform mental actions on actual objects and not in