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Optical illusions & the art of seeing

Explore optical illusions, impossible objects and illusion art with pictures, viewing instructions and explanations. Follow the science and history behind each example, from classic visual puzzles to fractals and camouflage in nature and human design.

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The collection

Three cylindrical prongs apparently connected to two rectangular supports.

Impossible trident

Original creator uncertain; reported by D. H. Schuster

Three prongs quietly become two supports.

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Sierpiński Carpet — A square becomes an endlessly nested lattice of holes.

Sierpiński Carpet

Wacław Sierpiński

A square becomes an endlessly nested lattice of holes.

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Vertumnus — Rudolf II appears as a face assembled from fruit, flowers, and vegetables.

Vertumnus

Giuseppe Arcimboldo

Rudolf II appears as a face assembled from fruit, flowers, and vegetables.

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An animated red-and-green ring with striped surfaces whose apparent depth can reverse.Moving image

Ambiguous Ring

Donald E. Simanek

You should experience a sense of perceptual confusion as you note the paradoxical nature of the depicted ring.

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Identical gray patches displayed on contrasting light and dark backgrounds.

Simultaneous contrast

Longstanding phenomenon; studied by Michel Eugène Chevreul

One gray looks light; the same gray looks dark.

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Repeating asymmetric light-to-dark gradients arranged in circular patterns.

Peripheral drift

Jocelyn Faubert & Andrew M. Herbert

Still gradients seem to drift at the edge of vision.

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Original plan-view diagram of Pepper’s Ghost: a hidden figure is reflected in angled glass, appearing as a virtual figure on the visible stage.

Pepper’s Ghost

Henry Dircks and John Henry Pepper

A figure appears on an empty stage, transparent enough for the scenery to show through. Its real source is hidden elsewhere.

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Bertrand’s 1865 engraving showing a Pepper’s Ghost stage, audience sight lines and the concealed illuminated figure beneath it.

Victorian ghost shows — Pepper at the Polytechnic

John Henry Pepper; optical arrangement developed with Henry Dircks

A ghost shares the stage with a living actor, then fades away. Victorian ghost shows turned hidden performers and sheets of glass into public spectacles of apparent presence.

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An animated black-and-white spiral used to induce a motion aftereffect.Moving image

Waterfall Illusion

Robert Addams popularised the illusion in 19th century; but it was known much before.

You should experience the dots in the test pattern as moving - even though they are stationary.

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Moiré Pattern — Overlapping fine patterns produce a larger rippling pattern.

Moiré Pattern

Pattern interference; drawing by Fibonacci

Overlapping fine patterns produce a larger rippling pattern.

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Adjacent unequal parallelograms containing two highlighted diagonals of equal length.

Sander’s parallelogram

Friedrich Sander; earlier Matthew Luckiesh

Equal diagonals look unequal inside different frames.

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Chevreul Staircase — Uniform gray steps appear shaded along their borders.

Chevreul Staircase

Michel Eugène Chevreul

Uniform gray steps appear shaded along their borders.

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The Hall of Perspectives at Villa Farnesina, with painted columns framing landscape views.

Walls That Become a Loggia

Baldassarre Peruzzi

A room’s walls appear to open through columns into the landscape beyond.

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Enlarged image from the selected gallery entry