Cats love boxes. It’s thought that this behaviour is driven by animal instinct: as ambush predators they’re attracted to confined places where they can hide, observe prey and feel safe.


The calming effect of this curious habit was proven in 2014, when a study carried out at the University of Utrecht found that shelter cats provided with boxes to hide in recovered more quickly and adapted to their new environments more easily than their box-less counterparts.

Now, a citizen science project led by Gabriella Smith from Columbia University, New York, has found that this behaviour is so ingrained in cats that they are even drawn to sit in square shapes created by optical illusions.

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The researchers asked cat owners to set up different shapes on their living room floors to see if the cats were compelled to sit in them. Some simply made a square out of tape on the floor while others set up an optical illusion known as the Kanizsa square – an arrangement of four Pac-Man-like shapes positioned to look as if they are forming the four corners of a square.

The Kanizsa figures trigger the perception of an actual square existing by tricking the brain into filling in the missing information. They also set-up a Kanizsa control pattern in which the Pac-Man shapes were reversed so no optical illusion was created.

They then had the owners record their cats’ behaviour over six days.

Cats sitting in the various squares © Gabriella Smith
Cats sitting in the various squares © Gabriella Smith

“The cats in this study stood or sat in the Kanizsa and square stimuli more often than the Kanizsa control, revealing susceptibility to illusory contours and supporting our hypothesis that cats treat an illusory square as they do a real square,” the researchers said.


The team say that the trial is limited by its small sample size, of the original 561 cat owners that signed up just 30 made it all the way through the experiment. But the findings confirm pre-existing research of cats’ susceptibility to optical illusions.

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Reader Q&A: Why are Sphinx cats hairless?

Asked by: Catherine Murphy, via email

It’s due to a mutation in the gene that is responsible for providing hairs with their keratin protein as they emerge from the follicle. The hair is formed, but it has a weaker structure and becomes easily damaged and dislodged.

This genetic mutation can occur in cats naturally, but selective breeding for this trait since the 1960s has produced the Sphynx breed. Some Sphynx cats are completely bald, while others have short downy fur over their bodies or in isolated areas.

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Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.