Why Cats Love to Sit in Boxes—Even Fake Ones, According to Science

It is no secret that cats adore sitting in anything square-like. Social media is filled with images of cats squeezing themselves into cardboard shipping boxes, baskets, suitcases, drawers, and plastic storage bins. In 2017, the social media tag #CatSquare showed multiple felines plopping themselves in square outlines on the floor made with masking tape.

A new study published in Applied Animal Behavior Science found cats were more likely to sit inside 2-D shapes that imitate an illusion of a square, and it may give researchers more insight into our furry friend’s perception of visual illusions, reports Ed Cara for Gizmodo. (The study is cheekily titled "If I fits I sits: A citizen science investigation into illusory contour susceptibility in domestic cats.”)

Study co-author Gabriella Smith, an animal cognition researcher at Hunter College in New York, first had the idea of testing a cat’s cognitive perception after hearing a lecture on a dog’s susceptibility to optical illusions and wondered if a domestic cat could also fall for visual trickery. “Cats like boxes and even shapes outlined on the floor—would they sit in a box that is an illusion?” Smith tells Gizmodo via email.

Smith and her team designed a citizen science experiment in which pet owners were instructed to create the illusion of shapes using paper and tape by creating corners without sides, reports Gizmodo. This exercise is known as the Kanizsa square illusion, which gives the perception of edges without the shape being there.

The "fake" square was made using four circles with 90 degree angles cut into them, sort of resembling Pac-Man. Each right-angle was used to create the illusion of a square’s corners, reports Tessa Koumoundouros for Science Alert. Once the paper shapes were made, the researchers instructed the citizen scientists to place the forms on the floor in various arrangements, reports Gizmodo. These arrangements included a regular square with edges, a perfect Kanisza square, and a misshapen Kanisza square.

To avoid any influence the cat owners might have on their feline, the owners were instructed to avoid interaction with their cats and wear sunglasses to avoid eye contact, reports Science Alert. The cats were filmed entering the room and researchers noted whether the cat sat or stood in one of the shapes for at least three seconds.

So pleased to announce that my paper, "If I Fits I Sits: A Citizen Science Investigation into Illusory Contour Susceptibility in Domestic Cats (Felis silvestris catus) has just been published in AABS! #IfIFitsISits #CatSquare #CitizenScience #CommunityScience pic.twitter.com/AXbDttnOGC

— Gabriella Smith M.A. (@Explanimals) May 4, 2021

In total, 500 cats were tested for their perception, but only 30 cat owners completed the experiment in its entirety of six days, reports Science Alert. From the sample size of 30 cats, nine cats consistently chose to sit in one of the shapes. Those nine cats sat on the regular square eight times, the perfect Kanizsa square seven times, and the misshapen Kanizsa square only once, Gizmodo reports.

“The major takeaways are that cats are susceptible to the Kanizsa illusion in a human-like way, and are most likely attracted to 2-D shapes for their contours (sides), rather than solely novelty on the floor,” Smith explains to Gizmodo.

Despite the small sample size, Smith found the cats selected the Kanizsa illusion almost as often as they chose the square. Their work is in line with previous studies about cats responding to visual illusions of sides, reports Science Alert. The study was also the first time cats were tested on visual illusions in an environment familiar to them, allowing them to behave naturally at home. In contrast, environments like lab settings are more likely to stress cats out, reports Gizmodo.

The findings in the study could help researchers understand how cats perceive illusions, which scientists could then compare to other animals, Science Alert reports.

So why do cats like to sit where they fit? More research is needed. Some researchers suspect it may provide a similar sense of security and safety that cats feel when they hide in an enclosed space, Nicholas Dodman wrote for the Conversation in 2017. To further study cats' collective obsession with boxes, Smith and her team hope to use 3-D Kanizsa squares next, reports Science Alert.

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.