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Archive for the ‘optical illusion’ Category


An optical illusion (also called a visual 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 percept 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 ones that are the effects on the eyes and brain of excessive stimulation of a specific type (brightness, tilt, color, movement), and cognitive illusions where the eye and brain make unconscious inferences. there are most types of illusions but mainly ebbinghaus,ponzo,necker and illusory motion illusions are known commonly.

Ebbinghaus illusion

In the best-known version of the illusion, two circles of identical size are placed near to each other and one is surrounded by large circles while the other is surrounded by small circles; the first central circle then appears smaller than the second central circle at Figure.1.


 Figure.1. The two orange circles are exactly the same size; however, the one on the left seems smaller.

Ponzo illusion

The Ponzo illusion is an optical illusion that was first demonstrated by the Italian psychologist Mario Ponzo (1882-1960) in 1913. He suggested that the human mind judges an object’s size based on its background. He showed this by drawing two identical lines across a pair of converging lines, similar to railway tracks. The upper line looks longer because we interpret the converging sides according to linear perspective as parallel lines receding into the distance. In this context, we interpret the upper line as though it were farther away, so we see it as longer – a farther object would have to be longer than a nearer one for both to produce retinal images of the same size.


Figure.2. An example of the Ponzo Illusion. Both horizontal lines are the same size.

Necker Cube

The impossible cube or irrational cube is an impossible object that draws upon the ambiguity present in a Necker Cube illustration. An impossible cube is usually rendered as a Necker Cube in which the edges are apparently solid beams. This apparent solidity gives the impossible cube greater visual ambiguity than the Necker Cube, which is less likely to be perceived as an impossible object. The illusion plays on the human eye’s interpretation of two-dimensional pictures as three-dimensional objects.


Figure.3. Viewed from a certain angle, this cube appears to defy the laws of geometry.

Illusory motion

The term illusory motion, also known as motion illusion, is used to define the appearance of movement in a static image. This is an optical illusion in which a static image appears to be moving due to the cognitive effects of interacting color contrasts and shape position.




Other Figures For Optical Illusion

**Try to count the number of black dots on the image below…


**Are the lines below straight or are they curved?


**How many legs does this elephant have?



**What do you see below?


    A lady or a musician? See both?

**The numbers 0 through 9 using only 8’s and 4’s!