According to Jean Piaget, a Swiss scientist, there are six stages of sensorimotor intelligence. However, Piaget categorizes them into 3 categories. Stage 1 and 2 are primary circular reactions, stage 3 and 4 are secondary circular reactions, and stage 5 and 6 are tertiary circular reactions.
Primary Circular Reactions: infants own body
Stage 1: From birth to 1 month. This stage consists of reflexes. Examples are sucking, grasping, staring, and listening.
Stage 2: From 1 to 4 months. The first acquired adaptations, which means adapting their reflexes to the environment. Children acquire new behaviors. Examples are sucking a pacifier differently than a nipple or grabbing a bottle to suck.
Secondary Circular Reactions: responses towards objects and other people
Stage 3: From 4 to 8 months. An awareness of things around them and responding to people and objects. Examples are clapping hands when mother says “patty-cake” or by kicking a child is able to make the mobile of her crib bounce.
Stage 4: From 8 to 12 months. New adaptations and anticipation break through. The child develops the ability to coordinate previously unrelated behaviors to achieve some desired end, they have acquired the concept of object permanence, their behavior is goal directed, and the child has the ability to use signs to anticipate events. Examples would be the child bringing his or her coat to the mother after seeing her put hers on or putting the mother’s hands together to get her to starts playing patty-cake.
Tertiary Circular Reactions: most creative, first with actions and then with ideas and symbolic representation.
Stage 5: From 12 to 18 months. New means through active experimentation, they become “little scientists.” Examples are flushing items down the toilet or squeezing the toothpaste out of the tube.
Stage 6: From 18 to 24 months. The child finding new means through mental combinations also known as the trial and error stage. Examples would include eating with a spoon or playing pretend.
This information came from my textbook for my Understanding Human Growth and Development class. Pages 165-170
The Developing Person: Through Childhood and Adolescence 7th Edition by: Kathleen Stassen Berger