An optical illusion or visual illusion is a perception deception of vision.
Optical illusions can affect virtually all aspects of vision. There are deep illusions, color illusions, geometric illusions, motion illusions, and some more. In all these cases, the visual system appears to be incorrect assumptions about the nature of the visual stimulus to hit as it can be shown with the aid of other senses, or by removing the triggering factors.
Optical illusions are examined in the psychology of perception, because from them conclusions about the processing of sensory stimuli in the brain can be obtained. Optical illusions are based on the fact that the perception is subjective and is influenced by the brain (see top-down and bottom-up). Systematically produced and analyzed optical illusions in the Gestalt psychology.