For an overview of the stages of sensorimotor thought, it helps to group the six stages into pairs.

The first two stages involve the infant’s responses to its own body, called primary circular reactions.

Stage One (birth to 1 month) Reflexes: sucking, grasping, staring, listening

Stage Two (1–4 months) The first acquired adaptations: accommodation and coordination of reflexes

Examples: sucking a pacifier differently from a nipple; attempting to hold a bottle to suck it

The next two stages involve the infant’s responses to objects and people, called secondary circular reactions.

Stage Three (4–8 months) Making interesting sights last: responding to people and objects

Example: clapping hands when mother says “patty-cake”

Stage Four (8–12 months) New adaptation and anticipation: becoming more deliberate and purposeful in responding to people and objects

Example: putting mother’s hands together in order to make her start playing patty-cake

The last two stages are the most creative, first with action and then with ideas, called tertiary circular reactions.

Stage Five (12–18 months) New means through active experimentation: experimentation and creativity in the actions of the “little scientist”

Example: putting a teddy bear in the toilet and flushing it

Stage Six (18–24 months) New means through mental combinations: thinking before doing, new ways of achieving a goal without resorting to trial and error

Example: before flushing the teddy bear, hesitating because of the memory of the toilet overflowing and mother’s anger