Five-month-old eric picks up his mother's keys and begins to put them in his mouth. his mother takes the keys away from eric, and he begins to cry. however, as soon as she puts the keys out of sight behind her back, eric stops crying and becomes interested in something else. this story demonstrates eric's lack of what?

Object permanence          

Explanation:

Jean Piaget has given his theory of cognitive development in 1936. In his theory, he has mentioned four stages of development in which object permanence comes under the first stage of development i.e the sensorimotor stage that lasts from birth to 18-24 months old.

Object permanence: This is the milestone of the sensorimotor stage. It is defined as the capability of a child to apprehend that an object exists even if it cannot be sensed or perceived (heard, touched, seen, etc). Object permanence develops between the age of 4-7 months.