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Cognitive Illusions

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Physiological Illusions
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Cognitive Illusions Literal Illusions
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Cognitive Illusions

Cognitive illusions are assumed to be an interaction based on assumptions about the world, which lead to unconscious inferences an idea first suggested in the 19th century by Hermann Helmholtz.

There are 4 categories of Cognitive illusions, they are:

  1. Distorting illusions are characterized by distortions of size, length, or curvature. A striking example is the Café wall illusion. Another example is the famous Müller-Lyer illusion.
  2. Ambiguous illusions are pictures or objects that elicit a perceptual ‘switch’ between the alternative interpretations. The Necker cube is a well known example; another instance is the Rubin vase.
  3. Paradox illusions are generated by objects that are paradoxical or impossible, such as the Penrose triangle or impossible staircases seen, for example, in M. C. Escher’s Ascending and Descending and Waterfall. The triangle is an illusion dependent on a cognitive misunderstanding that adjacent edges must join.
  4. Fictional illusions are defined as the perception of objects that are genuinely not there to all but a single observer, such as those induced by schizophrenia or a hallucinogen. These are more properly called hallucinations.

Illusion Deck 1: Distorting Illusions

Select the illusion you want to see by clicking on its title bar (on the left).

Black & White are the Same

Q: Do you think the square marked 'A'  is the same shade of gray as the square marked 'B'?

optical illusion same coloured squaree

A: Roll your mouse over the image to see if they are the same

Bendy Ruler

Q: Are the horizontal lines perfectly straight?

bendy lines illusiuon

A: Hold a ruler to the screen to find out (or download the image and print out)

Checkerboard Illusion

Q: Do the lines through the centre of the lego square look curved?

bent lines illusion

Click below to see the illusion change before your eyes

[rokbox title="Checkerboard." thumb="http://www.unisaustralia.com/wp-content/uploads/checkerboard-small.jpg" size="600 450" album="demo"]http://www.unisaustralia.com/wp-content/uploads/Checker_Board_Illusion_Video_Mighty_Optical_Illusions.flv&buffer=10&autostart=true&fullscreen=true&width=854&height=505[/rokbox]

Illusion Deck 2: Ambiguous Illusions

Hidden Necker Cube

Do you see the peace signs and arrows or the hidden Necker Cube?

ambiguous illusion 1

Old or Young lady

Do you see the old lady or young girl?

ambiguous illusion 2

Secret Writing

Do you see the words or the blocks?


hidden writing illusion

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