Sensorimotor Stage

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Piaget (1954, 1964) described this stage from birth to approximately 2 years as a period of rapid cognitive growth.

Initially equipped with a set of reflex movements and a set of perceptual systems, an infant quickly begins to build up direct knowledge of world through trial and error learning. Through the processes of assimilation and accommodation actions become progressively adapted to the world.

Infancy is characterized by extreme egocentrism, where the child has no understanding of the world other than her own current point of view. The main development during this stage is the understanding that objects exist and events occur in the world independently of one's own actions ('the object concept', or 'object permanence').

Object permanence means knowing that an object still exists, even if it is hidden. It requires the ability to form a mental representation (i.e. a schema) of the object.

For example, if you place a toy under a blanket, the child who has achieved object permanence knows it is there and can actively seek it. At the beginning of this stage the child behaves as if the toy had simply disappeared. The attainment of object permanence generally signals the transition to the next stage of development (preoperational).

piaget object permanence

Sub Stages

From careful observation of his own children (Jacqueline, Lucienne and Laurent) Piaget (1952) concluded that thought developed through 6 sub stages during the sensorimotor period.

  1. The first sub stage (first month of life) is the stage of reflex acts. The neonate responds to external stimulation with innate reflex actions. For example, if you brush a baby’s mouth or cheek with your finger it will suck reflexively.

  2. The second sub stage is the stage of primary circular reactions. The baby will repeat pleasurable actions centred on it’s own body. For example babies from 1 – 4 months old will wiggle their fingers, kick their legs and suck their thumbs. These are not reflex actions. They are done intentionally – for the sake of the pleasurable stimulation produced.

  3. Next comes the stage of secondary circular reactions. It typically lasts from about 4 – 8 months. Now babies repeat pleasurable actions that involve objects as well as actions involving their own bodies. An example of this is the infant who shakes the rattle for the pleasure of hearing the sound that it produces.

  4. The fourth sub stage (from 8 – 12 months) is the stage of co-ordinating secondary schemes. Instead of simply prolonging interesting events babies now show signs of an ability to use their acquired knowledge to reach a goal. For example the infant will not just shake the rattle but will reach out and knock to one side an object that stands in the way of it getting hold of the rattle.

  5. Fifth comes the stage of tertiary circular reactions. These differ from secondary circular reactions in that they are intentional adaptations to specific situations. The infant who once explored an object by taking it apart now tries to put it back together. For example it stacks the bricks it took out of its wooden truck back again or it puts back the nesting cups – one inside the other.

  6. Finally, in sub stage six there is the beginning of symbolic thought. This is transitional to the pre operational stage of cognitive development. Babies can now form mental representations of objects. This means that they have developed the ability to visualise things that are not physically present. This is crucial to the acquisition of object permanence – the most fundamental achievement of the whole sensorimotor stage of development.

Object Permanence Experiment

Blanket and Ball Study

Aim: Piaget (1963) wanted to investigate at what age children acquire object permanence.

Method: Piaget hid a toy under a blanket, while the child was watching, and observed whether or not the child searched for the hidden toy. Searching for the hidden toy was evidence of object permanence. Piaget assumed that the child could only search for a hidden toy if s/he had a mental representation of it.

Results: Piaget found that infants searched for the hidden toy when they were around 8-months-old.

Conclusion: Children around 8 months have object permanence because they are able to form a mental representation of the object in their minds.


Piaget assumed the results of his study occur because the children under 8 months did not understand that the object still existed underneath the blanket (and therefore did not reach for it). However, there are alternative reasons why a child may not search for an object:

The child could become distracted or loose interest in the object and therefore the lack motivation to search for it, or simply may not have the physical coordination to carry out the motor movements necessary for the retrieval of the object.

There is also evidence that object permanence occurs earlier than Piaget claimed. Bower and Wishart (1972) used a lab experiment to study infants aged between 1 – 4 months old. 

Instead of using a Piaget’s blanket technique they waited for the infant to reach for an object, and then turned out the lights so that the object was no longer visible. They then filmed the infant using an infra red camera. They found that the infant continued to reach for the object for up to 90 seconds after it became invisible.

Again, just like Piaget's study there are also criticisms of Bower's 'reaching in the dark' findings. Each child had up to 3 minutes to the complete the task and reach for the object. Within this time period it is plausible they may have successfully completed the task by accident. For example randomly reaching out and finding the object or even reaching out due to the distress of the lights going out (rather than reaching out with the intention of searching for an object.

Further Information

Jean Piaget

Preoperational Stage

Concrete Operational Stage

Formal Operational Stage

Cognitive Development

Piaget: Cognitive Development (Undergraduate Notes)

Sensorimotor Sub-Stages


Bower, T. G. R., & Wishart, J. G. (1972). The effects of motor skill on object permanence. Cognition, 1, 165–172.

Piaget, J. (1952). The origins of intelligence in children. New York: International Universities Press.

Piaget, J. (1954). The construction of reality in the child (M. Cook, Trans.).

Piaget, J. (1964). Part I: Cognitive development in children: Piaget development and learning. Journal of research in science teaching, 2(3), 176-186.

Piaget, J. (1963). The Psychology of Intelligence. Totowa, New Jersey: Littlefield Adams.

How to cite this article:

McLeod, S. A. (2015). Sensorimotor Stage. Retrieved from

piaget stage of development

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Piaget believed that children think differently than adults and stated they go through 4 universal stages of cognitive development. Development is therefore biologically based and changes as the child matures.

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