What is Optical Illusion

The broad definition of an optical illusion is essentially any image perceived by your eyesight to be visually deceptive.

For example, an optical illusion pertaining to color can be created when a bar of one color is surrounded by a box containing a gradation of color. The result of these two objects together cause us to perceive the bar within the box possesses a gradated color scheme as well, even though it is in actuality a single color.

An optical illusion occurs because the different cells and receptors of the eye perceive images and colors at different rates which sometimes result in a flase image beig relayed to the brain. The brain receives information from receptors in the eye, but in actuality, the eye only  perceives a certain quantity of visual information at any given time, while our brain continuously decodes, constructs and reconstructs visual information, giving us the illusion of continuos sight. The right combination of colors, shapes, spatial realtions, and other stimuli viewed by the eyes and reported to the brain during the relays of information can achieve the effect of an optical illusion

Types of Optical Illusion

Literal Illusions : 
The difference in the image and the actual physical objects that  make the picture.

Example :

Physiological Illusions : 
When the eyes or the brain get stimulated in excess by a particular type of stimulation. mainly like motion, color, brightness, tilt, etc.

Example :

Cognitive Illusions :
Based on the interactions with different levels perceptual processing and not physiological processing.

Example :