Cats, like people, can be fooled by optical illusions, nifty new research out this week suggests. The study, based on experiments conducted by pet owners at home, found that cats tend to sit inside 2D shapes that only look like squares about as often as they’ll sit inside a real square. The findings might give us a little more insight into cat cognition.
Whether they’re big tigers or domestic felines, cats just seem to love wedging themselves into boxes, crates, or other four-sided objects. This fascination doesn’t stop at 3D objects either, as the social media hashtag #CatSquare showed a few years ago; even using tape to make the outline of a square on the floor will entice cats ready to plop down at a moment’s notice.
Gabriella Smith, a recent master’s graduate from Hunter College in New York and animal cognition researcher, said inspiration for the study hit after she heard a lecture discussing dogs and their susceptibility to optical illusions and then arrived home and saw her roommate’s cat. The chance sighting, she said in an email, made her wonder: “Cats like boxes and even shapes outlined on the floor—would they sit in a box that is an illusion?”
It wasn’t until after May 2020, following her thesis defense, that Smith finally had the chance to test out her theory. By the summer, she and her colleagues put together a project asking pet owners to be scientists. On Wednesday, the findings of their study—aptly titled “If I Fits I Sits: A Citizen Science Investigation into Illusory Contour Susceptibility in Domestic Cats”—were published in Applied Animal Behavior Science.
With paper, scissors, and some tape, the owners were instructed to create several different shapes for the cats. This included the typical square, but it also included the Kanizsa square illusion, a pattern of Pacman-like shapes that fool the human brain into seeing a fully outlined square. For their control, they created a similar Kanizsa shape, but one where the illusion isn’t possible.
Once the shapes were put down on the floor, in various arrangements, the cats would enter the room. If they chose a shape to sit or stand inside for at least three seconds, the trial would be considered a success and their choice would be marked down. To monitor the trials remotely, the owners were asked to record the cats via a camera and smartphone. And to avoid influencing the cats in any way, they were told not to interact with them and to wear dark sunglasses so no eye contact could be made.
Ultimately, 30 owners completed the experiment in full, which involved six days of trials. Of these, nine cats were cooperative, meaning that they actually made a choice at least once during the trials. And out of the 16 times a choice was made, cats sat on the square eight times, the square-like illusion seven times, and the control illusion once.
“The major takeaways are that cats are susceptible to the Kanizsa illusion in a human-like way, and are most likely attracted to 2D shapes for their contours (sides), rather than solely novelty on the floor,” Smith said. “Furthermore, this study illuminates how cats are great candidates for citizen science: They have so many quirky behaviors that are just waiting to be harnessed to study their cognition!”
Smith was careful to note that the study’s sample size is small, so its findings shouldn’t be seen as the final word on cats’ perception of optical illusions. But they do support a 1988 study conducted in the lab with trained cats, which also suggested that cats could be fooled by the Kanizsa illusion. And because cats are especially prone to anxiety outside of their normal surroundings, it’s likely that these sorts of citizen science experiments allow a cat’s natural behavior to shine through more than it would in a lab. Relevant in these pandemic times is also the fact that Smith and her team were able to pull off this study without needing to risk any in-person contact indoors.
“Another advantage comes with citizen science: Many owners participated with their spouses or children, and that was very wonderful to see,” Smith said. “On the limitations side, this study was six days long, so an issue was participant attrition. However, I don’t blame owners for falling off the bandwagon—six days is a lot!”
Something that’s still mysterious is exactly why cats love squares in the first place. There are some working theories, such as the idea that it reflects their attraction to tight-fitting spaces, or that it’s related to their predatory instincts. But these explanations don’t necessarily explain why they’re drawn to 2D shapes and the theories are still pretty informal at this time, according to Smith.
Smith is now an animal cognition researcher at the Alex Foundation, which studies parrot behavior, as well as at Hunter College’s Thinking Dog Center. But she’d love to study other quirky aspects of the cat brain again.
“For example, I am fascinated by cat chattering/chirping behavior directed at prey such as wild birds,” she said. “Is this just a displacement behavior performed out of frustration as some suggest? Or does it inform the cats about the prey in some way?”
The experiment also helped inspire Smith to adopt her own cat afterward—a one-year-old tabby named Pancetta.
“And yes, every new delivery box has to be inspected by her in a thorough ‘If I Fits I Sits,’” she said.