nown as assimilation and accommodation are
thought to be responsible for changes in schema. Assimilation is
the cognitive process by which the person integrates new
perceptual matter or stimulus events into exiting schemata or patterns of behavior (Wadsworth, 1971, p. 14). However, while assimilation accounts for the way in which the individual organizes and adapts to his environment, it is the process of accommodation that accounts for the change in schemata. Accommoda-tion takes place when the child is not able to fit the incoming stimulus to the already existing schemata, in two ways. The child can create a new schemata in which to fit the new stimuli or the stimuli may be modified to fit already existing schemata. Both modes create changes or development of cognitive structures.
Equilibrium is the balance that takes place between assimilation and accommodation. It is necessary to insure an efficient interaction with the environment and is placement in the child's schemata is always considered appropriate to that person's level of conceptual development. This placement is not considered right or wrong but as better and better. These concepts are found to occur at all levels of Piaget's theory of cognitive development.
Piaget's theory of cognitive development is composed of four stages which proceed according to chronological age. However, a child might show aspects of a more advance stage at an earlier age and vice versa, but in one aspect Piaget is very definite. No child may pass through the stages except in the prescribed order. A more intelligent child may proceed more quickly than a slower child but they will both follow the same sequential stages of development.
The four stages are; the sensori-motor intelligence period (birth - 2 years), the preoperational thought period (2 - 7 years) the concrete operations period (7 - 11 years) and the formal operations period (1l - 15 years) (Wadsworth, 1971, page 26)...