One and a half decades ago, human development textbooks taught that babies of 6 months or younger had no sense of whether an object still exists even when it is out of sight. For example, if the parents were not in the same room as the infant, the infant believed that his parents did not exist anymore, which, in psychological terms is called not having a sense “object permanence”.
Nowadays psychologists know that the saying ‘out of sight, out of mind’ is untrue and does not automatically apply to young babies. The question is, how much can infants remember about their environment, and what specific information must be obtained by their brains to help them keep track of those things?
According to a new study by a Johns Hopkins psychologist and child development expert that was published in a recent issue of the journal Psychological Science, babies’ brains possess a set of built-in ‘pointers’ and although they are unable to remember details of an object they were shown and which was then hidden, these ‘pointers’ help them in retaining a notion that something they saw remains in their memory even when it is not in sight anymore.
Melissa Kibbe, a postdoctoral researcher at the Department of Psychological and Brain Sciences at the Krieger School of Arts and Sciences at Johns Hopkins, who both collaborated with Alan Leslie at Rutgers University commented:
“This study addresses one of the classic problems in the study of infant development: What information do infants need to remember about an object in order to remember that it still exists once it is out of their view? The answer is, very little.”
The team discovered that even though infants are unable to remember shapes of two hidden objects, they are surprised when those objects disappear completely, which leads researchers to the conclusion that babies can remember the existence of an object without remembering what that object is.
Kibbe, who did the majority of the work on this study while pursuing her doctorate in Leslie’s laboratory at Rutgers, highlights the importance of this discovery, saying that it gives an insight into the brain’s mechanisms that support memory in infancy and later.
“Our results seem to indicate that the brain has a set of ‘pointers’ that it uses to pick out the things in the world that we need to keep track of. The pointer itself doesn’t give us any information about what it is pointing to, but it does tell us something is there. Infants use this sense to keep track of objects without having to remember what those objects are.”
The study, which was supported by the National Science Foundation, could also assist other researchers in establishing a more precise timeline regarding infants and children’s mental milestones.
In their study, researchers first placed a triangle behind a screen whilst being watched by 6-month-old babies, before they placed a second item (a disk) behind the screen. When they removed the first screen to reveal the expected original triangle, the unexpected disk, or nothing at all, they observed the infants’ reactions and measured the time span of the infant looking at the expected outcomes compared with the unexpected outcomes.
The observed that the babies hardly appeared to notice a difference when the objects were swapped, suggesting that they did not retain a memory of the object’s shape. In the babies’ mind a triangle and a disk were virtually identical, whereas when one of the objects had disappeared, the babies were surprised and looked for a longer period of time at the empty space, suggesting they expected something to be there where they saw something previously.
Leslie of Rutgers concluded:
“In short, they retained an inkling of the object.”
Written by Petra Rattue