“Impossible objects” like the etchings of M.C. Escher have fascinated adults for centuries. You can’t help but stare and wonder at a drawing like this, which seems to defy the laws of nature:
The drawing seems strange to us because our visual system tells us that when an object or part of an object occludes another, it’s in front. Since the parts of the cube are all connected, it’s clear that the vertical bar in the “back” of the cube shouldn’t be in front of any other bars.
Some research has suggested that young babies don’t have the same ability as adults to determine how close objects are to them. Babies younger than 6 months, for example, aren’t able to reach the right distance for objects after seeing a three-dimensional display. But babies do recognize real objects after seeing pictures, and they recognize possible and impossible events involving solid objects. Can they recognize impossible objects?
A team led by Sarah Shuwairi showed an image like the one above to 10 four-month-olds, but with one crucial difference: the portion of the image determining whether the object was possible or impossible was obscured with a red oval:
This image was shown to them repeatedly, at least five times, until they were obviously quite bored with it (they were “habituated”). Then they were shown the entire, unobscured object. The “possible” cube was alternated with the “impossible” cube six times, so each cube was viewed a total of three times. An experimenter watching on video pressed a button when the baby looked at the cubes, so that the total looking time for each type of object could be computed. Here are the results:
The babies looked significantly longer at the impossible cube, suggesting that this was a surprising or novel object to them.
The study was repeated on a new set of infants, but instead of using a realistic image, they were just shown a line-drawing. This offers much less detail, and only one method of determining whether the object is possible or impossible. This time some infants were habituated as before, while others were just shown the possible and impossible objects without habituation. Here are those results:
In both cases, once again, the babies looked at the impossible objects longer than the than the possible objects — suggesting that these objects were novel or surprising to them.
The researchers say this demonstrates that infants are able to use the relative placement of objects (occlusion) to make judgments about how far away the objects are. Even at this early age, their visual system is able to make some of the same types of depth judgments as adults are.
Perhaps more importantly, this suggests that very young infants might already be able to appreciate the work of M.C. Escher!
Sarah M. Shuwairi, Marc K. Albert, Scott P. Johnson (2007). Discrimination of Possible and Impossible Objects in Infancy Psychological Science, 18 (4), 303-307 DOI: 10.1111/j.1467-9280.2007.01893.x