Egocentrism, in relation to child development, is a characteristic of Piaget's child development stage of preoperational thought. This trait, usually present in 2-4 year olds, occurs regularly in the symbolic function substage. The concept here is the child now realizes that an object or person exists whether they can see it or not and can even create a mental image of it but cannot distinguish between their own perspective and someone else's. The affect of this is they act according to their own perspective.

The best example of egocentrism is a young child on the telephone. When talking to perhaps their parent they may be asked a question. They have a mental image of the person on the other end of the line but instead of saying "yes" to answer the question, the child will nod. They have the concept of the person existing regardless of presence but the perspective is egocentric and they nod assuming that if they can see themselves nod then that is good enough.

Piaget and Barbel Inhelder's research with this used a three-mountain model. Three model mountains were setup and the child was allowed to walk around them to see them from different sides and see the objects on them. Then the child is seated and a doll is moved around the mountains. The child is then asked to describe, or point to a picture of, what the doll sees. Children experiencing egocentrism will describe each viewpoint, regardless of where the doll is, as their own since they cannot distinguish between the two.

Resources include, but are not limited to: Piaget, J. & Inhelder, B. (1969). The child's conception of space (F.J. Langdon & J.L. Lunzer, Trans.). New York: W.W. Norton.