A-not-B error

From Freepedia

A-not-B error was a term coined by Jean Piaget, referring to a particular error made by young children during substage 4 of their sensorimotor stage. This is all part of his classic theory of cognitive development.

The error is made by infants who have successfully uncovered a toy at location "A", and continue to reach to that location even after they watch the toy hidden in a nearby location "B." This demonstrates a lack of, or otherwise incomplete, object permanence.

The exact cause of A-not-B errors seems to be a little harder to uncover than we might expect. Tradionally it has been explained as the child seeing an image and remembering where it was, rather than where it is. However a more comprehensive view takes into account the development of planning, reaching, and deciding things.