How do visual illusions occur?

Visual illusions can be broadly divided into three groups.

Physiological illusions are visual illusions in which pictures or patterns that do not actually exist are seen as a result of excessive stimulation of the eyes or brain due to light and color differences or movement. In these illusions, external stimuli are thought to create a change in the perception of the image by stimulating the brain more than once at different stages of the visual process.

Literal illusions are visual illusions where multiple images come together to form a different image. In this case, each of the pictures that make up the main picture can be easily distinguished. But the main picture is completely different from the thumbnails that make it up. Even though there are gaps between small pictures, our brain fills these gaps and ensures the perception of the big main picture. Therefore, we can see different images when we focus on different parts of the picture.

Perceptual illusions are visual illusions that result from making unconscious inferences based on one's perspective.

Research on visual illusions allows neuroscientists to obtain valuable information about the interaction between the eye and the brain and how the brain makes sense of perceptual spaces. Understanding the mechanism of visual illusions in the brain can be used in daily life. For example, when pilots are in the air, they may encounter visual illusions such as the vanishing line or the narrowing runway. Special trainings are given to pilots in order to recognize such situations and to safely land the aircraft in this case.