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Illusions

Posted by Allen

There are several different kinds of illusions. Some of them are color illusion, size illusion, geometrical illusions, motion illusions etc. Here are some really interesting types of illusion.

The Jastrow illusion is an optical illusion discovered by the American psychologist Joseph Jastrow in 1889. In this illustration, the two figures are identical, although the lower one appears to be larger.

Kanizsa Triangle. These spatially separate fragments give the impression of illusory contours (also known as modal completion) of a triangle

The Ehrenstein illusion is an optical illusion studied by the German psychologist Walter Ehrenstein in which the sides of a square placed inside a pattern of concentric circles take an apparent curved shape.

The Ponzo illusion is a geometrical-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.

Delboeuf illusion. It is an optical illusion of relative size perception.

Delboeuf illusion, underestimation of the outer circle. Here, the circle appears to be smaller than it is when a slightly smaller circle is drawn in it.

Delboeuf illusion, overestimation of the inner circle. A circle appears to be larger than it is when it is surrounded by a slightly larger circle.

Delboeuf illusion, underestimation of the inner circle. A circle appears to be smaller than it is when it is surrounded by a much larger circle.

Müller-Lyer illusion. The two horizontal bars are the same in length but the lower one appears to be much longer than the upper one.

The Necker Cube is an optical illusion first published as a rhomboid in 1832 by Swiss crystallographer Louis Albert Necker.

The Necker Cube is an ambiguous line drawing.The effect is interesting because each part of the picture is ambiguous by itself, yet the human visual system picks an interpretation of each part that makes the whole consistent. The Necker Cube is sometimes used to test computer models of the human visual system to see whether they can arrive at consistent interpretations of the image the same way humans do.

The Ebbinghaus illusion or Titchener circles is an optical illusion of relative size perception discovered by the German psychologist Hermann Ebbinghaus (1850-1909). 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.

The Hermann grid illusion is an optical illusion reported by Ludimar Hermann in 1870.The illusion is characterised by “ghostlike” grey blobs perceived at the intersections of a white (or light-colored) grid on a black background. The grey blobs disappear when looking directly at an intersection.

The scintillating grid illusion is an optical illusion, discovered by E. Lingelbach in 1994, that is usually considered a variation of the Hermann grid illusion. Dark dots seem to appear and disappear rapidly at random intersections, hence the label “scintillating”. When a person keeps his or her eyes directly on a single intersection, the dark dot does not appear. The dark dots disappear if one is too close to or too far from the image.

The Wundt illusion is an optical illusion that was first described by the German psychologist Wilhelm Wundt in the 19th century. The two red horizontal lines are both straight, but they look as if they are bowed inwards. The distortion is induced by the crooked lines on the background, as in Orbison’s illusion. Hering illusion produces a similar, but inverted effect.

The Hering illusion is a one of the geometrical-optical illusions and was discovered by the German physiologist Ewald Hering in 1861 . Two straight and parallel lines look as if they were bowed outwards. The distortion is produced by the radiating pattern and was ascribed by Hering to an overestimation of the angle made at the points of intersection.

The Orbison illusion is an optical illusion that was first described by the psychologist William Orbison in 1939. The bounding rectangle and inner square both appear distorted in the presence of the radiating lines. The background gives us the impression there is some sort of perspective. As a result, a distorted shape is seen. This is a variant of theHering and Wundt illusions.

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. Here are some examples of motion illusion.

The circles appear to rotate in the different directions when we approach or move away from the figure while fixating at the center

The inset appears to move in the horizontal direction

For more than half people, the black heart appears to move

These circles appear to rotate in clockwise or counterclockwise

The inset appear to move

Looks like 3 worms are on the move

Dots appear to move when the image slips vertically

The circles appear to rotate

The inset appears to move

The center block and the flanking blocks appear to move relative to each other

When look closer or move away from the image keeping eyes fixed on the center, the rings appear to rotate in the different directions

When observers look close or move away from the image keeping their eyes fixed on the center, the rings appear to rotate in the different direction. Each pictures differ in the direction of movement!

Looks like ripples in a pond

The picture appears expanding

The circles appear to rotate in the different directions when we approach or move away from the figure while fixating at the center

Expanding and contracting squares!

Looks like fireworks in a dark night

Expanding and contracting illusion

Appears like heat shimmer

The inset appears to move

The inset appears to hop slightly

The circles appear to expand

Ouchi illusion. It is an illusion named after its inventor, Japanese artist Hajime Ouchi. In this illusion, the central disk seems to float above the checkered background when moving the eyes around while viewing the figure

Each row appears to move in the horizontal direction

Appears like a spiral, but actually they are separate circles

The inset appears to fluctuate

The inset appears to move

When observers look close or move away from the image keeping their eyes fixed on the center, the rings appear to rotate in the different directions.

The inset appears to move

The inset appears to move slightly

When observers look close or move away from the image keeping their eyes fixed on the center, the rings appear to rotate in the different directions.

The inset appears to move

For more than half people, the red ring appears to be in front of the blue “earth”. In addition, they appear to move.

The inset appears to hop

Zöllner illusion. It is a classic optical illusion named after its discoverer, German astrophysicist Johann Karl Friedrich Zöllner. The short lines seem to be unparallel, but in reality they are parallel.