While for many infants a thing out of sight is also out of mind, there is a developmental milestone, called object permanence, that children reach when he or she realizes that the object exists even when it can’t be seen. The term was coined by child development expert and psychologist Jean Piaget. Piaget believed most children reached the object permanence stage when they were about eight or nine months old. However, all children develop slightly differently, and may reach this stage earlier or later than others.
Piaget studied the concept of object permanence by conducting relatively simple tests on infants. He would show an infant, or young baby a toy and then cover it with a blanket. A child who had a clear concept of object permanence might reach for the toy or try to grab the blanket off the toy. A child who had not yet developed object permanence might appear distressed that the toy had disappeared.
Parents, of course, have tested object permanence for years with young babies. Games of peek-a-boo with a three month old are quite delightful because the child will often be pleasantly surprised each time one covers one’s hands with one’s face and then reappears. According to Piaget’s theory, the delight results in the sudden reappearance of the parent, who magically disappeared and came back. Children over five or six months may also hide under blankets and expect that their parents can’t possibly find them, since the child cannot see the parent.
Lack of object permanence might also explain why children tend not to fuss as much when they are younger and the parent leaves. Yet this is not always the case, and calls into question some of Piaget’s theories. For instance, studies testing breastfed week-old infants suggest they can easily differentiate between their mother’s breast milk and other breastmilk. Basing the concept of object permanence on what can be only visually perceived discounts what can be heard, smelled or touched.
In complete dark for instance, a baby far too young to have developed object permanence may feel comforted by the touch and smell of a mom sleeping nearby or picking up the baby. The mother exists even before the sight of the mother can be determined. Thus vision cannot be the only factor guiding object permanence.
However, it is clear that as infants begin to expand their visual perception they may seem quite surprised by the sudden visual disappearance of a beloved toy or person. They may however be still able to smell, hear or sense the missing object. This suggests that the infant has more ways of perceiving than were summarized by Piaget in his development and testing of the theory of object permanence.
