Fish susceptible to optical illusions

Scientists from the School of biological Sciences at the University of Queensland and Kvinslendskih brain Institute found that fish family spinarova (lat. Balistidae), common in the waters of the Great Barrier reef, in the same way as we can be deceived by optical illusions.

According to Dr. Karen Cheney, illusions constitute an interesting area of study. “They demonstrate a situation when our brain is not able to perceive the true properties of what we consider, from the point of view of color, brightness, size, shape, and movement,” she said. — “It is not clear why we see illusions, but there are a few different ideas. In General, it is known that they occur due to processes on the retina or in the nerve pathways closer to the brain”.

To determine whether fish perceive complex illusion in the same way as men, Dr. Chaney, Professor Justin Marshall, and student Elisha Simpson held a “cubic illusory test”.

In an experiment that still baffles observers and not fully explained by science, the orange square on the cube seems very different from the brown square on the side, but actually their color and brightness are identical. Scientists believe that the illusion occurs because the brown color is perceived in the shadows, and so our brain encodes it darker “orange”.

First fish learned to swim to a pair of squares where one was brown and one orange, the rest of the image was filled with gray background. Four fish were trained to peck an orange square, and the other four brown. in the case of a “hit” in “his” square, the fish received the food. Then the fish showed the cube, where all the colors were different, but it was not orange instead it was identical to brown in color, but the apparent “orange” fragment on the shady side.

In the experiment it turned out that fish also take brown over orange, as the fish, accustomed to the orange most often chose the brown on the light side, and brown to brown to dark. In other words, the subjects chose “their” square.

It’s quite interesting, says Dr. Cheney, that, apparently, different types of deceptive perceive things similarly to humans. Since the nervous system of fishes is less complex, it is possible that at least part of their basic mechanisms of illusory perception was formed in the early stages of visual evolution.
To know, perceive whether the fish this imaginary difference in color, the team used behavioural experiments reward in the form of food.

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