Classic geometrical illusion

Access since September 18, 2004


The central circle appears to be slightly smaller than the flanks but theys are identical in size.

Copyright A.Kitaoka 2004 (September 18)

Is it size contrast?


Although the width of each rectangle is the same as the gap between two adjacent rectangles, the former appears to be shorter than the latter. In addition, the ellipses or rectangles appear to move horizontally.

Copyright A.Kitaoka 2004 (May 17)

"The shortening bar illusion"

The two black bars are identical in size but the left one appears to be shoter than the right one.

Copyright A.Kitaoka 2004 (May 14)

"Sasaki's modification of the Bourdon illusion"

The left image shows that the top-left sides of the two black triangles are actually aligned but appear to be convex toward top-left, while the right image does not show this illusion or possibly gives the reversal.

Copyright Takayuki Sasaki 2004 (April 9, 2004)
SASAKI Takayuki, one of Akiyoshi's undergraduate students, Department of Psychology, Ritsumeikan University, Japan, 2004/4/9

"The Lipps illusion of curvature of uzumaki ampan"*

*Uzumaki ampan means pieces of bread including anko (sweet food)

Each top of the upper row as well as each bottom of the lower row are linearly aligned but appear to curve inward (Lipps illusion of curvature). Concentric circles appear to be a spiral (spiral illusion). In addition, weak rotating illusion is also included.

Copyright A.Kitaoka 2004 (March 10, 2004)

"The orthogonal Zollner illusion"

The black verticals or horizontals appear to be distorted.

Copyright A.Kitaoka 2003

"A tilt"

The circles are actually aligned horizontally, but appear to tilt down to the right.

Copyright A.Kitaoka 2003

"Strange appearance"

The two rings are concentric but appear to be strange. Two types of anomalous motion illusions also contribute to this appearance.

Copyright A.Kitaoka 2003

"Half circles"

The two half circles are the same size but appear to be different from each other in shape.

Copyright A.Kitaoka 2003


Circles appear to change their sizes though they are identical. In addition, a small, black dot sparkles in each circle.

Copyright A.Kitaoka 2003

"Cat's eyes"

Free-fuse the nearest neighbors, then you see figures like cat's eyes. In addition, the central circle is the same size as the flanks but appears to be smaller.

Copyright A.Kitaoka 2002


The central circle appears to be shorter in height than the flanks. If you put the cursor on the figure, the blue crescents disappear and the circles appear to be the same in size.

Copyright A.Kitaoka 2002


*kind of lamps

Circles of the same size appear to be different in size. If you put the cursor on the figure, the oblique lines disappear and the circles appear to be the same in size

Copyright A.Kitaoka 1999


The left Y-junctions appear to lie higher than the right counterparts though they are horizontally aligned. This is a variation of the Müller-Lyer illusion.

Copyright A.Kitaoka 2001

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