Classic geometrical illusion 17

Classic geometrical illusion 17

since May 14, 2011

"Endo's size illusion"

In each circle, the middle part appears to be smaller or shorter than the rest, though they are of the same size.

Professor Mitsuo Endo, University of the Ryukyus, discovered this illusion.

This illusion cannot be explained with Kanizsa amodal expansion.

amodal expansion and amodal shrinkage

References

Kanizsa G, Luccio R, 1978 ``Espansione di superficie da completamento amodale'', reports from the Institute of Psychology, University of Trieste, Trieste, Italy.

Vezzani, S. (1999) Shrinkage and expansion by amodal completion: a critical review. Perception, 1999, 28, 935-947.

"Soccer"
(a remake)

The image consists of only squares but it appears to be distorted.

"Length illusion of the Kanizsa square"

The gap of adjacent pacmen appears to be shorter than the radius of them, though they are the same length.

"A size illusion of chromatic Mach band rings"

The illusory blue ring in the left disk appears to be smaller than the illusory yellow ring in the right disk.

The size illusion is reversed by reversing the gradation.

"An illusion of squares"

The right square appears to be larger than the left one though they are the same size.

"Diamond"

Radial lines appear to be parallel every two pairs.

"Chopsticks"

The upper black rectangle appears to taper to the left while the lower one to the right.

"Shepard illusion with Mona Lisa"

The left Mona Lisa appears to be slimmer than the right one.

"Shepard illusion with Mona Lisa 2"

The left Mona Lisa appears to be taller than the right one.

"Mona Lisa sisters"

The left Mona Lisa appears to be taller than the right one (Müller-Lyer illusion or Waite-Massaro illusion).

"Necktie illusion"

The rectangle with a necktie appears to be slimmer than that without necktie.

"An illustration of Yang's iris illusion"

The four irises are placed with the same interval. When each iris is relatively located toward the nasal side within the eye contour ("Asian" faces), the interval of both irises in a face appears to be larger than the interval between the middle two. On the other hand, when each iris is relatively located toward the temporal side within the eye contour ("Caucasian" faces), the interval of both irises in a face appears to be smaller than the interval between the middle two. These effects were proposed by Yang and Schwaninger (2011).

References

Yang, J. and Schwaninger, A. (2011). Yang's iris illusion: External contour causes length-assimilation illusions. Japanese Psychological Research, 53, 15-29. Abstract

Top 10 of the Best Visual Illusion of the Year Contest 2008

Another demo

Akiyoshi's comments

The authors claimed Yang's iris illusion is quite new because this illusion is featured by length-assimilation though e.g. the Giovanelli illusion is a length-contrast effect. To my knowledge, however, the gravity-lens illusion (Naito and Cole, 1994) shows a length-assimilation effect. In each of the images shown below, four small dots are placed on the apices of a virtual parallelogram but the position of each dot appears to be shifted toward the large circle nearby.

References

Naito, S. and Cole, J. B. (1994) The gravity lens illusion and its mathematical model. in G. H. Fischer and D. Laming (Eds.), Contributions to Mathematical Psychology, Psychometrics and Methodology. New York: Springer-Verlag (pp. 39-50).

Both Yang's iris illusion and the Giovanelli illusion work simultaneously.

T-shaped illusion (Lee and Freire, 1999)

The left ellipse appears to be taller and narrower than the right one, though they are the same shape and size.

Reproduced on May 21., 2011

References

Lee, K. and Freire, A. (1999). Effects of face configuration change on shape perception: A new illusion. Perception, 28, 1217-1226.

Yang, J. and Schwaninger, A. (2011). Yang's iris illusion: External contour causes length-assimilation illusions. Japanese Psychological Research, 53, 15-29. Abstract