During the first few months of a baby’s life, only what he or she can see with his or her eyes exists; meaning everything that is left outside his or her field of vision ceases to exist. But from the age of four months, he or she begins to understand, very slowly and progressively, that not seeing an object does not mean that it has ceased to exist but is simply not within reach of sight.

This ability, fundamental to understanding the world around us and relating to it, is called “object permanence”, and the baby will develop it during the first two years of life.

The Swiss psychologist, biologist and researcher, Jean Piaget, was the first to study object permanence in infants and children. To do so, he relied on observing their reactions when presented with a toy and then hiding it under a blanket.

According to Piaget, babies who had begun to develop the understanding of object permanence would try to grab the blanket to discover the toy, while those who had not yet developed it would be confused at what happened.

The permanence of the object evolves in the baby throughout the first two years of life, distinguishing the following stages:

1. During the first four months, babies relate to their environment through the senses and primitive reflexes. Everything the baby cannot see; smell or feel does not exist.
2. From four to eight months, babies begin to develop object permanence, but in a very subtle way. According to Piaget, while the object is in the baby’s visual field, he or she will follow it with his or her gaze and try to reach it, as he has already acquired enough dexterity to coordinate his hand-eye movements. However, if before your eyes we hide the object under a handkerchief, the baby will believe that it has simply disappeared and will do nothing to recover it.
3. From eight to 12 months, the baby already fully understands that objects exist even if they disappear from sight, but he or she still does not have enough ability to look for them when we hide them, unless we always do so in the same place or hide it before his or her eyes.
4. From 12 to 18 months, the baby is able to find any object we hide within his or her field of view, searching the hiding places we have used other times. However, if out of his sight we hide the object in a new place, he or she will not think of looking for it there, because he or she has not yet acquired the inner representation of the object to imagine it hidden anywhere else.
5. From 18 to 24 months, the baby already understands that we can hide the object anywhere, even if he or she did not see us. This happens because the child is already able to mentally represent the object and imagine it anywhere.

Piaget’s theory has been much discussed over the years, as there are researchers who consider that object permanence is acquired by the baby much earlier. To this day there is no scientific consensus on when exactly children acquire this skill.

In any case, it should be mentioned that as in any other childhood milestone, each child has their own rhythms, so the stages that Piaget classifies are not set in stone.

What is clear is that the baby’s acquisition of “object permanence” is a very important step for his or her development, because thanks to this he or she begins to understand that objects and people have an independent and permanent (they still exist even if they cannot see them) existence.

The acquisition of the object permanence’ is closely related to the separation distress developed by babies around the eighth month of life.

At the moment the babies begin to understand that their attachment figures are independent people with an existence of their own, losing sight of them will deeply distress them, for although they understand that they have not disappeared, they are not able to understand when they will see them again or if they have abandoned them forever.

Although object permanence is a natural skill that babies develop on their own over time, as with other skills such as spatial orientation or assimilation of the concept ‘time’, parents can encourage it through play.

In this sense, hide-and-seek games are the activity par excellence, although we must adapt them to the age of the baby, as the concept of permanence of the object evolves. Montessori’s permanence boxes are also a fantastic resource for the child to begin to understand that the things put in the box do not disappear even if they are not visible.