What Happens During the Sensorimotor Stage of Cognitive Development?

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Swiss psychologist Jean Piaget developed a defining theory of childhood development which posits that children progress through a series of four critical stages of cognitive development. Each stage is marked by shifts in how children understand and interact with the world around them. 

Piaget's four stages of intellectual development included the sensorimotor stage, from birth to about age 2; the preoperational stage, from age 2 to about age 7; the concrete operational stage, from age 7 to 11 and the formal operational stage, which begins in adolescence and continues into adulthood.

The Sensorimotor Stage

This the earliest in Piaget's theory of cognitive development. He described this period as a time of tremendous growth and change.

During this initial phase of development, children experience the world and gain knowledge through their senses and motor movements. As children interact with their environments, they go through an astonishing amount of cognitive growth in a relatively short period of time.

The first stage of Piaget's theory lasts from birth to approximately age 2 and is centered on the infant trying to make sense of the world. During the sensorimotor stage, an infant's knowledge of the world is limited to his or her sensory perceptions and motor activities. Behaviors are limited to simple motor responses caused by sensory stimuli.

Children utilize skills and abilities they were born with (such as looking, sucking, grasping, and listening) to learn more about the environment.

Object Permanence

According to Piaget, developing object permanence is one of the most important accomplishments at the sensorimotor stage of development. Object permanence is a child's understanding that objects continue to exist even though they cannot be seen or heard.

Imagine a game of peek-a-boo, for example.

A very young infant will believe that the other person or object has actually vanished and will act shocked or startled when the object reappears. Older infants who understand object permanence will realize that the person or object continues to exist even when unseen.

Substages of the Sensorimotor Stage

The sensorimotor stage can be divided into six separate sub-stages that are characterized by the development of a new skill:

  1. Reflexes (0-1 month): During this substage, the child understands the environment purely through inborn reflexes such as sucking and looking.
  2. Primary Circular Reactions (1-4 months): This substage involves coordinating sensation and new schemas. For example, a child may suck his or her thumb by accident and then later intentionally repeat the action. These actions are repeated because the infant finds them pleasurable.
  3. Secondary Circular Reactions (4-8 months): During this substage, the child becomes more focused on the world and begins to intentionally repeat an action in order to trigger a response in the environment. For example, a child will purposefully pick up a toy in order to put it in his or her mouth.
  4. Coordination of Reactions (8-12 months): During this substage, the child starts to show clearly intentional actions. The child may also combine schemas in order to achieve a desired effect. Children begin exploring the environment around them and will often imitate the observed behavior of others. The understanding of objects also begins during this time and children begin to recognize certain objects as having specific qualities. For example, a child might realize that a rattle will make a sound when shaken.
  1. Tertiary Circular Reactions (12-18 months): Children begin a period of trial-and-error experimentation during the fifth substage. For example, a child may try out different sounds or actions as a way of getting attention from a caregiver.
  2. Early Representational Thought (18-24 months): Children begin to develop symbols to represent events or objects in the world in the final sensorimotor substage. During this time, children begin to move towards understanding the world through mental operations rather than purely through actions.


Piaget, J. (1977). Gruber, H.E.; Voneche, J.J. eds. The Essential Piaget. New York: Basic Books.

Piaget, J. (1983). Piaget's Theory. In P. Mussen (ed). Handbook of Child Psychology. 4th edition. Vol. 1. New York: Wiley.

Santrock, John W. (2008). A Topical Approach to Life-Span Development (4 ed.). New York City: McGraw-Hill.