September 22, 2005
in Young Perceptionist's Seminar 2005
Cháteau de L'espoir, Fureai-no-oka
Ohtawara city, Tochigi, Japan

Illusion design "Turtles"

Lecture after receiving the first Imai Award (Award of Illusion House) 2004

Akiyoshi KITAOKA
Department of Psychology, Ritsumeikan University, Kyoto, Japan

since September 22, 2005

"Turtles"

geometrical illusion

Vertical or horizontal edges appear to tilt.

"Turtles: Day and Night"

Each turtle appears to tilt counterclockwise. This image is a figure-ground reversible one, too.

Turtles

Illusion of fringed edges

"Cultured turtles"

geometrical illusion with 3D appearance

Vertical or horizontal edges appear to be distorted and the image appears to wave.

"Turtle spirals"

(Kame wa mannen)

spiral illusion (geometrical illusion)

The concentric arrays appear to be spirals.

Kitaoka, A., Pinna, B., and Brelstaff, G. (2001). Last but not least: New variations of spiral illusions. Perception, 30, 637-646. (p. 642, Figure 6c) PDF request

"Turtle spirals 2"

(Kame wa mannen 2)

spiral illusion (geometrical illusion)

The concentric arrays appear to be spirals.

"Midorigame"*

*Green turtle.

anomalous motion illusion

The inset appears to move.

Ascending and descending turtles"

geometrical illusion and anomalous motion illusion

Vertical edges appear to tilt and the image appears to be unstable.

The elemental illusion of illusion designs "Turtles" is

Illusion of fringed edges.

Elemental images

The horizontal edge in the middle of each image appears to tilt counterclockwise. This illusion was proposed by Kitaoka, Pinna and Brelstaff (2001, 2004).

References

Kitaoka, A., Pinna, B., and Brelstaff, G. (2001). New variations of spiral illusions. Perception, 30, 637-646.

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

"Men with sunglasses"

geometrical illusion

Vertical or horizontal edges appear to be distorted and each quarter region appears to move.

"Noshi"*

*kind of decorations for cerebration

geometrical illusion

Inner gold squares appear to tilt counterclockwise.

"Field of flowers"

The horizontally or vertically aligned blue squares appear to tilt.

The elemental image of primrose's version

"Primrose's field"

geometrical illusion with 3D appearance and anomalous motion illusion

This checkered background consists of squares but appears to wave. In addition, this figure shows a great amount of anomalous motion illusion.

"Primrose's hill"

geometrical illusion with 3D appearance and anomalous motion illusion

It looks as if the checkered surface bulges out, though this figure actually consists of squares.

"Bulge of the ground surface"

The image appears to bulge out.

"Primrose's spirals"

spiral illusion (geometrical illusion)

Concentric arrays of "flowers" appear to be spirals.

"Rotation of primroses 2"

spiral illusion (geometrical illusion) and rotating illusion (anomalous motion illusion)

When we approach or move away from the figure fixing our eyes at the center, the hidden ring appears to rotate.

"Potted plants"

Plants appear to move.

The elemental image
(copyright free; citation is necessary)

The horizontal edge on which black or white stars are placed appears to tilt counterclockwise. This configuration includes anomalous motion illusion, too.

Kitaoka, A., Pinna, B., and Brelstaff, G. (2001). New variations of spiral illusions. Perception, 30, 637-646.

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

Also see:

Kitaoka, A. (2002) Trick Eyes. Tokyo: Kanzen.

Kitaoka, A. (2003) Trick Eyes 2. Tokyo: Kanzen.　

Nearly elemental image

"The autumn color swamp"

The inset appears to move.

"Neural circuits"

The two concentric arrays of stars appear to rotate in the different directions when we approach or move away from the figure while fixating at the center.