Jean Piaget's conclusions from his work with children continue to exert the most lasting influence on cognitive developmental theory. This approach sees cognitive development as essential to moral, ethical, and self-concepts. To Piaget, humans develop through attempting to understand and to adapt to their environments.

Terms:

1. Assimilation - the process of adding new material/information to an existing schema
2. Accommodation - the process of altering or revising an existing schema in light of new information
3. Equilibration - keeping balance by creating new concepts
4. Schema - a system of organized general knowledge stored in long-term memory that guides the encoding and retrieval of information.

Piaget's Stages of Cognitive Development:

1. Sensorimotor Stage (birth to 2 years)
a. Knowledge gained through active interaction with environment
b. Beginning awareness of cause and effect relationships
c. Learning that objects exist even when not in view (object permanence)
d. Crude imitation of actions of others

2. Pre-operational Stage (ages 2 to 6 years)
a. Initially very egocentric
b. Development of language and mental representations
c. Classification of objects by a single characteristic at a time

3. Concrete Operations Stage (ages 6 to 12 years)
a. Understanding of conservation of volume, length, etc.
b. Organization of objects into ordered categories
c. Comprehension of rational terms (i.e., bigger than, above)
d. Beginning use of simple logic

4. Formal Operations Stage (over 12 years of age)
a. Thinking becomes abstract and symbolic
b. Development of reasoning skills and a sense of hypothetical concept

These four stages apply to all individuals and indicate a qualitative process, not a quantitative one (i.e. children do not just tack on additional information to their knowledge base, rather they change HOW they think as they go through these developmental stages).