Source/credit: Hosico Cat
Can animals see optical illusions?
Many animals will fall for the same optical illusions as we humans do. Studies have been done with all kinds of animals ranging from birds (parrots, pigeons, doves, chickens) to monkeys (capuchins, rhesus, macaques) and from cats (domestic and large) to sharks and even fruit flies.
By tricking animals with optical illusions and watching them fall for it or not, we not only learn a lot about the vision of other species, but also about perception and the evolution of brains. Optical illusions, of course, have more to do with perception than vision. It is the misinterpretation of visual cues by the brain.
It turns out that most animals process visual information in the same way as we do and will fall for similar optical illusions. A few surprising results were the fact that sharks cannot be tricked with the Müller-Lyer illusion. They will not think that one is bigger than the other. And birds can actually be tricked by forced perspective illusions.
How do scientists know?
You may wonder how scientists do studies with animals to see if they would fall for optical illusions. Animals are first trained to make a distinctinction between different shapes, lengths of an object, or colors.
For example, in one study a fish tank with a circle on one side and a triangle on the other side was used to train fish. By always giving food near the triangle, the fish would learn to stay near the triangle. Even if the triangle was not real, but just an optical illusion, the fish would stay near it waiting for food, no matter on which side of the tank the image was placed.
Test your cat’s ability to see optical illusions
Where it may seem a lot of work to train a goldfish to discriminate between different shapes, it is not difficult to make use of natural characteristics of some animals. Your house cat probably loves to sit in boxes. Most cats do. It is very easy for you to create the illusion of a box (Kanizsa square) with some tape on the floor and see if the cat is interested in sitting inside this “box”.
Another optical illusion that will work great on cats, but also many other animals is the perception of illusory motion. Many animals will follow a moving object with their eyes, or turn towards it with their body. Presenting your pet with a static image that appears to be in motion, like the famous rotating snakes illusion, should give a similar reaction as when they would actually see a moving object. Your cat will probably attempt to catch the rotating snakes illusion.
You may also have seen videos on social media where people have bought a rug or mat with an optical illusion on it, and filmed the reaction of their pets to it. Newly appeared sinkholes, vortexes and stairs have tricked many cats and dogs already.
Animals using illusions in nature
There are also animals who trick other animals with optical illusions of their own. This is usually a defense mechanism or a means to catch prey. Think about:
- Camouflage. Colors and patterns on an animal are often to make them blend in with their backgrounds. The arctic fox is white as snow, a gecko or owl blends in perfectly with a tree. A chameleon is even capable of changing its color in order to blend in better. Sometimes animals have a camouflaging shape, like stick insects.
- Motion dazzle is a pattern that helps prey when it is moving by confusing the predator. The stripes on a zebra make it hard to pick out an individual when it is moving in a group. (A group of zebras is called a dazzle.) Dragonflies also use motion dazzle to make it hard to judge their speed or trajectory.
- Mimicking and shape changing. An octopus is a master of deception and can mimic objects and other animals to confuse predators. The Attacus Atlas also uses an illusion as defense.
Optical illusions featuring animals
We have a collection of all our optical illusions and accidental illusions featuring animals on this site, organised by species and properly sourced. Please link to the original source if you want to use any of these images in social media.