A four-stage theory of how cognition, thinking, and reasoning develop in and throughout the lifecourse.
The stage from birth until about two years old where humans primarily "know" the world through their physical senses of touching, smelling, tasting, seeing, and hearing.
The stage from ages two to seven where humans learn to use symbols and language.
The stage from approximately ages seven to eleven where children learn to recognize cause and effect relationships in their environment.
The stage from approximately age 12 onwards where we can think abstractly and use advanced symbolic representation.