What Is Object Permanence?

How Infants Know That Unseen Objects Continue to Exist

Object Permanence during peek-a-boo
Bambu Productions / The Image Bank / Getty Images

The term object permanence is used to describe a child's ability to know that objects continue to exist even though they can no longer be seen or heard.

If you have ever played a game of "peek-a-boo" with a very young child, then you probably understand how this works. When an object is hidden from sight, infants under a certain age often become upset that the item has vanished. This is because they are too young to understand that the object continues to exist even though it cannot be seen.

Object Permanence and Piaget's Theory of Development

The concept of object permanence plays a significant role in the theory of cognitive development created by psychologist Jean Piaget. In the sensorimotor stage of development, a period that lasts from birth to about age two, Piaget suggested that children understand the world through their motor abilities such as touch, vision, taste, and movement.

During early infancy, babies are extremely egocentric. They have no concept that the world exists separate from their point of view and experience. To understand that objects continue to exist even when they are unseen, infants must first develop a mental representation of the object.

Piaget referred to these mental images as schemas. A schema is a category of knowledge about something in the world. For example, an infant might have a schema for food, which during early infancy will be either a bottle or breast.

As the child grows older and has more experiences, his or her schemas will multiply and become much more complex. Through the processes of assimilation and accommodation, children develop new mental categories, expand their existing categories, and even completely change their current schemas.

How Does Object Permanence Develop?

So how exactly do infants develop object permanence?

At what age does it begin to emerge? Piaget suggested that there were six substages that occur during the sensorimotor stage of development.

  1. Birth to One Month: Reflexes
    During the earliest part of the sensorimotor stage, reflexes are the primary way that infants understand and explore the world. Reflexive responses such as rooting, sucking, and startling are how the infant interacts with its environment.

  2. One to Four Months: Development of New Schemas
    Next, primary circular reactions lead to the formations of new schemas. A baby might accidentally suck on his thumb and realize that it is enjoyable. He will then repeat the action because he finds it pleasurable.

  3. Four to Eight Months: Intentional Actions
    Around the ages of four to eight months, infants begin paying much more attention to the world around them. They will even perform actions to create a response. Piaget referred to these as secondary circular reactions.

  4. Eight to Twelve Months: Greater Exploration
    Between eight and twelve months, intentional actions become much more evident. Babies will shake toys to produce sounds and their responses to the environment become more cohesive and coordinated.

  5. 12-18 Months: Trial-and-Error
    Tertiary circular reactions appear during the fifth stage. These involve trial-and-error, and infants might start performing actions to gain attention from others.

  1. 18-24 Months: Object Permanence Emerges
    Piaget believed that representational thought begins to emerge between 18 and 24 months. At this point, children become able to form mental representations of objects. Because they can symbolically imagine things that cannot be seen, they are now able to understand object permanence.

How Did Piaget Measure Object Permanence?

To determine if object permanence was present, Piaget would show a toy to an infant before hiding it or taking it away. In one version of his experiment, Piaget would hide a toy under a blanket and then observe to see if the infant would search for the object.

Some of the infants would appear confused or upset by the loss while other infants would instead look for the object. Piaget believed that the children who were upset that the toy was gone lacked the understanding of object permanence, while those who searched for the toy had reached this developmental milestone. In Piaget’s experiments, this tended to occur around the age of 8 months.

Recent Findings Suggest Object Permanence Occurs Earlier

While Piaget’s theory was enormously influential and remains quite popular today, it has also been the subject of criticism. One of the major criticisms of Piaget’s work is that he often underestimated children’s abilities.

Recent research on object permanence has also called into question some of Piaget's conclusions. Researchers have been able to demonstrate that children as young as three-and-a-half months can understand that objects continue to exist even though they are unseen or unheard.

Other researchers have suggested alternative explanations for why infants do not look for hidden toys. Very young children simply may not have the physical coordination necessary to search for the item. In other cases, babies might simply not have an interest in finding the hidden object.


Baillargeon, R, DeVos, J.Object permanence in young infants: further evidence". Child Development. 1991; 62(6): 1227–46. doi:10.2307/1130803. PMID 1786712

Bower, T.G.R. Development in infancy. San Francisco: Freeman; 1974.