I had previously been under the impression that babies don’t have object permanence– the knowledge that things continue to exist when you’re not looking at them. However, I recently learned that the balance of the evidence in developmental psychology is that babies have object permanence from an extremely young age.

If babies perceived the world as a series of images rather than a set of stable permanent objects, they wouldn’t have size constancy– that is, they wouldn’t understand that if a near object is moved farther away, then it’s the same object. However, research suggests they do. One- and two-month old babies who receive a reward when they move their head in the presence of a certain box move their head when that box is placed farther away, but do not move their head when a smaller box is placed closer.

In another experiment, infants were shown a screen which moved back and forth 180 degrees, then shown a box centered behind the screen. When the box stopped the screen, the infants were unsurprised; however, when the screen passed through the box, the infants were surprised– even though they couldn’t see the box through the screen. (You can tell when infants are surprised because they look at the event longer.) By extension, five-month-olds must understand not only that things continue to exist when they can’t look at them but also that solid objects do not move through the space occupied by other objects.

In a third experiment, “Object permanence and identity in Piaget’s theory of infant cognition”, done by G Butterworth in 1981, which unfortunately does not appear to be on Google Scholar which is why I am giving you all this information, infants whose mothers broke eye contact and looked at a specific point on the wall also looked at that point on the wall. Thus, the infants understood that something might be happening that their mother could see and they couldn’t, and turned their heads to look at it– implying knowledge of a stable and enduring world.

The most delightful experiment along these lines replicated the original research that found that infants were confused about object permanence. In the original experiments, the experimenter several times placed the rattle under blanket A in full view of the infant; the infant retrieved it. The experimenter then placed the rattle under blanket B in full view of the infant; the infant proceeded to look under blanket A and then get confused and do something else. The new experiment changed one detail: it left out the blankets. Instead, the child had to get a toy that was in a new location which it could see. The infant continued to look in location A for the toy even when the infant could see it was in in location B– therefore, this strange behavior could not possibly be a product of lack of object permanence.

In a similar study, the experimenters turned the baby around 180 degrees before putting the rattle in location B. This time, the baby correctly grabbed the toy. On the other hand, if they turned the baby around 180 degrees and continued to put the rattle in location A, the baby would fail to grab the toy. In conclusion, the real explanation isn’t that babies lack object permanence; it’s that babies tend to remember “this is the action I need to perform to obtain the toy”, rather than coming up with a plan like “I am going to figure out where the toy is and then obtain it.”