Optical illusion is characterized by visually perceived images that differ from objective reality. The information gathered by the eye is processed in the brain to give a perception that does not tally with a physical measurement of the stimulus source. There are three main types: literal optical illusions that create images that are different from the objects that make them, physiological illusions that are the effects of excessive stimulation of a specific type (brightness, colour, size, position, tilt, movement), and cognitive illusions, the result of unconscious inferences. Pathological visual illusions arise from a pathological exaggeration in physiological visual perception mechanisms causing the aforementioned types of illusions.
Many artists in the past explored this kind of representation such as Salvador Dalì. He was fascinated with optical effects and visual perception. Dalì’s paintings present his use of various pictorial techniques, photography, and holograms to further his exploration of visual perception and the ways that optical illusion affects our sense of reality. You can see below a collection of his development of the famous double image, the “paranoiac-critical method” that produced images that could be “read” in multiple ways.
‘Old couple or musician” (1930)
“L’Amour de Pierrot” (1920)