Youtuber rasmusab has posted a video that's as adorable as it is thought provoking. In it, a small orange kitten with white feet appears transfixed by an 8.5 x 11 printout of the famous "rotating snakes" illusion (just one variation on the "peripheral drift illusion" — see an example for yourself below). The kitten paws at it in vain, presumably attempting to pin down the parts of the picture that appear to be moving at the fringes of its vision. Then again, it could just be batting at the sheet of paper. Because it's a kitten, etc.
"My cat can see the rotating snake illusion!" writes rasmusab, who encourages other cat owners to try the experiment for themselves and add their observations to this Google doc. "If enough people do this we might be able to crowdsource some real evidence that cats can see visual illusions!"
The experiment is already well under way, and results have been... mixed. Redditor st33lb0ne posted a picture of their cat's reaction that highlights a flaw in the study's design, namely: we can't say the cat doesn't see the illusion, just that it isn't reacting to it:
If we had to make a wild guess we'd say that cats probably can see the optical illusion, reason being that the mammalian visual system is pretty highly conserved (plus, scientists still aren't totally clear on the mechanisms at work when humans fall for it — see the "Potential Mechanisms" section of this paper). We're honestly not sure whether a crowdsourced internet experiment comprising Google doc surveys could give rise to publishable data or not — but having seen the video, and the kinds of responses it's already generating, we at the io9 Internal Review Board grant our enthusiastic approval of this adorable animal protocol. Please feel free to contact us when seeking peer review.