Cats perceive more than meets the eye

Research investigating cats’ susceptibility to illusory contours shows they percieve space in much the same ways as humans.

Story by Rei Fortes.

Cats have highly developed senses that aid their active lifestyle including advanced vision that makes their eyes six times more sensitive to light compared to humans. The vision of cats also plays a key part in identifying complex shapes, colours and sizes of objects similar to an average person. The process of perceptual closure allows the brain to fill in the missing information of an incomplete shape using previous experiences and knowledge.

“The brain fills in a lot of things with visual information. It takes the information it needs and reconstructs some kind of image that we experience that’s in our conscious awareness,” says Associate Professor Philippe Chouinard from the Department of Psychology and Counselling at La Trobe University.

In 2017 pet owners began sharing images on social media of their cats sitting in 2D squares under the hashtag #CatSquare. This indicated to Professor Chouinard that cats have a sense of complex visual perception. He collaborated with researcher Gabriella Smith and Sarah-Elizabeth Byosiere from Hunter College at the University of New York to conduct a study on domesticated cats and their ability to perceive 2D shapes compared to 3D enclosures.

The study involved over 500 pet cats and owners participating, with 30 completing all six trials. Due to the COVID-19 pandemic, Associate Professor Chouinard and his collaborators had to test alternative methods for the study.

“We had the idea of doing what’s called community-based research. This is research where you actually have volunteers as citizen scientists and they receive a bunch of specific instructions and do the experiments in their own houses,” says Associate Professor Chouinard.

The trials in the study made use of the phenomenon with cats’ tendency to sit in enclosed spaces by requiring owners to construct a kanizsa square illusion. This illusionary contour experiment was created by Gaetano Kanizsa in 1955 by using pacman shaped objects to form the suggestion of an enclosed shape.

“What happens is that the pacmans are positioned in a way that suggests that there might be a square there. When you have a machine, like the brain that takes shortcuts, there’s that suggestion and it’ll just fill it in,” says Associate Professor Chouinard.

“Apparently cats also have that ability which is absolutely remarkable. The cat brain utilizes shortcuts and these shortcuts lead to similar perceptual illusions as humans.”

The study showed that the cats recognised the kanizsa square illusion by sitting in the test area for a few seconds. Pet owners also recorded results showing their cats sitting in a 2D square that was also part of the trials.

“The fact that cats are behaving in such a way in response to seeing an illusion suggests that they’re having that perceptual filling in leading to some kind of awareness,” says Associate Professor Chouinard.

The research study published by Associate Professor Chouinard and his collaborators s the first published citizen scientist study on cat cognition, along with analysing cats’ attraction to 2D shapes compared to 3D objects and investigating cats’ susceptibility to illusory contours.

“Looking at simpler animals allows us to better appreciate the aspect of vision. It enables us to understand what a cat sees, how a cat sees and can appreciate more of their visual world and what they might be experiencing.”

Associate Professor Chouinard and his collaborators are already conducting a follow-up study with cats to see if they have perceptual experiences similar to humans when it comes to illusions. The study will focus on the cats’ ability to perceptually rescale shapes and objects to show an indication of having awareness.