Jean Piaget's Theories on a child's cognitive development are the most known of all cognitive development theories. Although greatly criticized for his depiction of children' s thinking being more continuous than it is, underestimating infants' and young children's cognitive competency, the absence of an explanation for the cognitive processes that give rise to children's thinking, what mechanisms produce its growth, and how underplayed the contribution of the child's social world is within his descriptive theories, these theories are still widely recognized as the most influential in understanding cognitive development.

Piaget took a constructivist approach to children: he viewed kids as typically active participants in the evolution of their own development- learning most of the larger concepts on their own and internally motivated. He described their development as a simple result of the interaction between their assimilation, accommodation and equilibration of new information: integrating new information into a form they could understand, changing their knowledge structures in accordance to the new information they had acquired, and creating a more stable understanding at the end of the whole process. (Click on the file below to see this concept represented visually.)





Piaget viewed children's development as discontinuous and organized it in stages set by the child's age.

Stage Name
Age Range
Description
Sensorimotor Stage
0- 2
years of age

Infants explore the objects in their world through their five senses, e.g. feeling the petals of a flower, smelling its sweet odor, and then trying to eat it to get a better understanding of its taste and possible uses.
Preoperational Stage
2- 7
years of age

Children in this stage begin to be able to represent their world through language and symbolic imagery. However, children are considered limited by their own perspective, unable to recognize that others' may have one that differs from their own, and exhibit problems understanding the concept of conservation.
Concrete Operational
7- 12 years of age
At this stage children are enabled to think logically, categorize objects, and understand that events can be influenced by more than one factor. At this stage they are no longer limited by their own perspective and are now able to begin to see the world through other people's perspectives as well as their own or at the very least recognize that others may have a different ones. Children no longer have trouble with the conservation concept.
Formal Operational
12 years of age and older
At this stage individuals can think abstractly and reason on a higher level, understanding concepts like politics, philosophy, humanitarian ethics, etc.

In accordance with the common belief that a large part of the cognitive development of children occurs in the first two years Piaget naturally went more into detail in describing these with his sensorimotor substages.

Substage
Age Range
Description
1
0-1
month
Infants adapt innate reflexes for more purposeful uses.
2
1-4
months
Infants organize and connect said reflexes to larger behaviors centered around their own bodies.
3
4-8
months
Infants become more interested in their surroundings, and develop a concept of object permanence.
4
8-12 months
Children often make "A-Not-B errors" in which they reach for objects where they have been previously found as opposed to their last hiding place.
5
12-18 months
Toddlers actively explore and manipulate the objects within their environment.
6
18-24 months
Children retain formed mental representations and exhibit deferred imitation.

*All information on this page was derived from source number 2 found on reference page.*

For more information about Piaget and his theories visit:
http://webspace.ship.edu/cgboer/piaget.html
http://video.google.com/videoplay?docid=-9014865592046332725#