SCIENCE

Seeing isn't believing: Mind-bending optical illusions

Is reality an illusion? Whatever the case may be, our brain has a nasty habit of playing tricks on us, bending objective reality into the subjective. Scientists have just solved the mystery behind one optical illusion, but the wide world of illusions continues to confound.

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In this illusion, the white square on a black background appears larger than the same-size black square on a white background.

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A static image appears to be moving due to the cognitive effects of interacting color contrasts and shape position.
Fiestoforo

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Shape, position, colour, and 3D contrast converge to produce the illusion of black dots at the intersections.
António Miguel de Campos

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The edges between the diamond-shaped areas are straight lines.
Wikimedia

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The two circles seem to move when the viewer's head is moving forwards and backwards while looking at the black dot.
Fibonacci

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Stare at the crosshair long enough and the pink dots seem to disappear.
Wikimedia

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The two orange circles are the same size.
Wikimedia

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Spiral illusion.
Nevit Dilmen

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The Poggendorff illusion: Does the black line connect to the blue or the red line?
Fibonacci

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Mysid/Wikimedia

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Cornsweet illusion: The left part of the picture seems to be darker than the right one. In fact they have the same brightness.
Fibonacci

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The Fraser spiral illusion: The overlapping black arc segments appear to form a spiral; however, the arcs are a series of concentric circles.
Mysid

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The Zöllner illusion: Despite their appearance, the black lines are parallel.
Fibonacci

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All lines and edges are strictly horizontal/vertical, and fully parallel/perpendicular to each other but may appear otherwise.
Wikimedia

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Delboeuf illusion: the two dark circles are the same size.
Wikimedia

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Moving the image dissociates circle and background.
Nevit Dilmen

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The red-orange lines are strictly horizontal/vertical, and fully parallel/perpendicular to each other, but may appear otherwise.
Wikimedia

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The impossible cube.
Wikimedia/Wapcaplet

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An optical illusion similar to Rotating Snakes by Kitaoka Akiyoshi.
Cmglee

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The square A is exactly the same shade of gray as square B. Don't believe us? Here's proof.

Edward H. Adelson/MIT

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Café wall illusion: the horizontal lines are parallel, even if they seem otherwise.
Fibonacci

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Look at the red squares. Are they crooked?
Nevit Dilmen

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The Wundt illusion: The two red vertical lines are both straight, but they may look as if they are bowed inwards to some observers.
Fibonacci

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The Hering illusion: Two straight and parallel lines look as if they were bowed outwards.
Fibonacci

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This is not a GIF.
Nevit Dilmen

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Each one of the four lines is of the same length, even if the horizontal red one seems shorter.
Wikimedia

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Rectangles A, on the left, look much darker than the rectangles B, on the right. However, rectangles A and B reflect the same amount of light.
Wikimedia/Zhengyi4411

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The two squares are the same size.
Nevit Dilmen

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The "Blivet" or "Poiuyt" impossible object shown against a warped checkerboard optical illusion background. There are no curved lines in the picture, except the ovals at the ends of the tines of the fork.
Wikimedia

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Kanizsa's Triangle: These spatially separate fragments give the impression a bright white triangle, defined by a sharp illusory contour, occluding three black circles and a black-outlined triangle.
Fibonacci

Seeing isn't believing: Mind-bending optical illusions

Is reality an illusion? Whatever the case may be, our brain has a nasty habit of playing tricks on us, bending objective reality into the subjective. Scientists have just solved the mystery behind one optical illusion, but the wide world of illusions continues to confound.

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