Science and art of visual illusions

Memorial Talk of the Gold Prize of the 9th L'ORÉAL Art and Science of Color Prize
Izumi Garden Gallery; December 1, 2006
Award news   Four seasons in Japan   Lipsticks

Gold prize

by Tini & Einen Miura

Akiyoshi Kitaoka (Department of Psychology, Ritsumeikan University)

since November 30, 2006    Japanese

1. What is visual illusion?

1.1 Motion illusion in a stationary image

"The time tunnel show"

Rings appear to rotate.

Copyright Akiyoshi.Kitaoka 2006 (February24)

"Brownian motion"
(a remake)

Particles appear to move.

Copyright Akiyoshi Kitaoka 2006 (September 6)

"The autumn color swamp 2"

The inset appears to move.

Copyright Akiyoshi Kitaoka 2003 (corrected April 12, 2006)

"Soft magnets"

The blue and yellow bars are actually rectangles but appear to be distorted.

Copyright Akiyoshi Kitaoka 2005 (June 18)

Macromedia Flash Player is necessary. For QuickTime version, click here.

For reversed phi movement, see Professor Anstis' site.

1.2 Color illusion

"Lemon-yellow spiral and cream-colored spiral"

It appears as if there were a lemon-yellow spiral and a cream-colored spiral, but the colors are identical (= yellow: R255, G255, B0).

Copyright Akiyoshi Kitaoka 2005 (April 22)

"Four tanks"

There are two pairs, each of which consists of two squares of the same color. Which are the two pairs?

Copyright Akiyoshi Kitaoka 2006 (May 1)

Answer: the pair of the leftmost square and the neighboring one, and the pair of the rightmost square and the neighboring one

"Sakai's color contrast"

The squares of the upper row appear to be gray, but they are tinted as shown in the lower row that exchanges between the left fives and the right fives. This illusion is based upon a finding of Kasumi Sakai's graduational thesis (2003, Department of Psychology, Ritsumeikan University) entitled "Color representation by Land's retinex theory and Belsey's hypothesis" (in Japanese).

Copyright A.Kitaoka 2002

Larger image

Contrast of color

1.3 Brightness or lightness illusion

"The morning sunlight"

It appears as if intense morning sunlight were projected.

Copyright Akiyoshi.Kitaoka 2005 (April 5)

The four squares are identical in luminance. 

"Light of Sweden"

Blue light appears to scintillate in white circles.

Copyright Akiyoshi.Kitaoka 2005 (April 25)

I have never been to Sweden...

For the scintillating grid illusion, see below.
Schrauf, M., Lingelbach, B., Wist, E.R. (1997) The scintillating grid illusion. Vision Research, 37, 1033-1038.

1.4 Shape illusion (Geometrical illusion)

"Baby turtles lightened by the moon"

Each border of adjacent turtles is vertical or horizontal, but appears to be tilted by the illusion of fringed edges (Kitaoka et al., 2004). In addition, the turtles appear to wave.

Copyright Akiyoshi Kitaoka 2006 (June 17)

Kitaoka, A., Pinna, B., and Brelstaff, G. (2004). Contrast polarities determine the direction of Café Wall tilts. Perception, 33, 11-20.

"Packed spirals"

Concentric rings appear to be spirals. Moreover, each set of rings appears to rotate.

Copyright Akiyoshi .Kitaoka 2006 (June 13)

"Sakushi hakken! Kakenhi kofu"

Some rows appear to tilt counterclockwise while the others clockwise. These Chinese characters mean "Discovery of illusion! Grant is awarded".

Copyright Akiyoshi Kitaoka 2006 (July 22)

1.5 Binocular stereopsis or space perception

"3D-wave of the autumn color swamp"

The image appears to wave in depth.

Copyright Akiyoshi.Kitaoka 2006 (August 22)

By the way, Ritsumeikan University

"Lake Ritsumeikan"

It appears as if there were a lake in the campus of the Ritsumeikan University.

Copyright A.Kitaoka 2006 (August 14)

Original photo

Kinkaku (Golden Palace)
One of the most popular sightseeing spots in Kyoto

This lake is real.

Ten minutes walk from the Ritsumeikan University

2. How have I won the Gold Prize?

Applied works and paper

1. Illusion design "The four seasons in Japan"
2. Illusion design "Lipsticks"
3. Paper entitled
     "The effect of color on the optimized Fraser-Wilcox illusion"
          (MS-Word file, 75MB !)

Graphic summary of the paper

"Rotating snakes"

Circular snakes appear to rotate 'spontaneously'.

Copyright A.Kitaoka 2003 (September 2, 2003)

The page of "Rotating snakes"
The page of "Rotating snakes 2"
The page of "Rotating snakes 3"
The page of "Rotating snakes 4"

Explanation of the elemental illusion (optimized Fraser-Wilcox illusion) (PDF)

My current classification of the optimized Fraser-Wilcox illusion

The following is explanation using Type I

Black » Gray; White » Gray

Black » Gray

White » Gray

Black » Gray  is replaced with  Black » Magenta

Observation 1 The illusion from dark to light is enhanced by red or blue.

White » Gray  is replaced with  Yellow » Green

Observation 2 The illusion from light to dark is enhanced by yellow or green.

Black » Gray  is replaced with  Black » Magenta

White » Gray  is replaced with  Yellow » Green

Observation 3 The illusion from dark to light is enhanced by red or blue, and the illusion from light to dark is enhanced by yellow or green. Both illusions work additively.


Illusion design should contribute even more to the development of the science and art of color!

This Japanese phase "Arigato gozaimashita" means "Thank you".

Akiyoshi's illusion pages