Color illusions and others

October 26, 2022, 20:30 pm - 22:00 pm (Japan Standard Time)
for L'Oreal

Akiyoshi Kitaoka, Ph.D, professor, Ritsumeikan University email

since October 22, 2022

Self-introduction

Born in Japan, in 1961. I am a psychologist studying perception. My research is in vision, especially visual illusions. Today I will talk about visual illusions (optical illusions). Before that, I would like to thank L'Oreal for awarding me the L'Oreal prize in 2006.

I am sorry I do not speak English very well but I will do my best.

A variety of visual illusions

"Rotating snales"

Disks appear to rotate.

version 2015

Color is not indispensable. Gray-scale images also work.

"Rotating snakes: a gray scale version"

Each disk appears to rotate 'spontaneously' in the constant direction, from black to dark gray, white, light gray, back to black.

A few years ago I discovered the color-dependent motion illusion.

Figure 6 of Kitaoka, A. (2014). Color-dependent motion illusions in stationary images and their phenomenal dimorphism. Perception, 43(9), 914-925.

More info:

Phenomenal review

Kitaoka, A. (2016). Visual phantoms and perceptual transparency. in Thematic Session entitled "The visual phantom illusion revisited" organized by Jiro Gyoba, 31st International Congress of Psychology (ICP2016), PACIFICO Yokohama, Japan, July 25, 2016. Presentation (html)

Kitaoka, A. (2017). The Fraser-Wilcox illusion and its extension. A. G. Shapiro and D. Todorović (Eds.), The Oxford Compendium of Visual Illusions, Oxford University Press, pp. 500-511. PDF --- Figures

An fMRI study

As if in response to illusory motion, motor response areas (human MT+) of the brain are activated by the illusion.

Kuriki, I., Ashida, H., Murakami, I., & Kitaoka, A. (2008). Functional brain imaging of the Rotating Snakes illusion by fMRI. Journal of Vision, 8(10):16, 1-10. PDF

Journal of Vision Volume 8, Number 10, Article 16, Pages 1-10

Functional brain imaging of the Rotating Snakes illusion by fMRI
Ichiro Kuriki
Hiroshi Ashida
Ikuya Murakami
Akiyoshi Kitaoka
http://journalofvision.org/8/10/16/

"Pumpkin"

The pumpkin appears to move when the image is swayed.

"Swaying heart"

When the image is moved, the heart appears to sway.

Reference

Kitaoka, A. & Ashida, H. (2007). A variant of the anomalous motion illusion based upon contrast and visual latency. Perception, 36, 1019-1035.

"Black hole"

The black hole appears to expand. (a variation of Kouki Fujiwara's illusion and design)

Fujiwara, K., Matsuda, H., & Kitaoka, A. (2018). A proposal of designs of a new motion illusion. The Heisei-29th Kansai Branch Meeting of the Color Science Association of Japan, Osaka Electro-Communication University, Campus in front of the station, March 3, 2018 (poster presentation).

Expanding hole illusion

Laeng, B., Nabil, S. & Kitaoka, A. (2022). The eye pupil adjusts to illusorily expanding holes. Frontier Human Neuroscience, 16:877249. doi: 10.3389/fnhum.2022.877249 https://doi.org/10.3389/fnhum.2022.877249 --- All figures

https://twitter.com/AkiyoshiKitaoka/status/1531549301213921280

https://twitter.com/BrunoLaeng/status/1531523205915197441

cf.
Laeng, B. and Endestad, T. (2012). Bright illusions reduce the eye's pupil. Proceedings of the National Acedemy of Sciences of the United States of America (PNAS), February 7, vol. 109 no. 6 2162-2167.

http://www.pnas.org/content/109/6/2162

& ScienceShot: Brightness Is in the Eye of the Beholder

Your pupil may be constricted!

illnews15e.html

"Drifting Gabor patches illusion"

The inset/surround appears to move.

"A train"

A stopped train appears to run right.

Kitaoka, A. (2021). "Luminance change-dependent motion illusions"　A talk in the 15th Illusion Workshop, March 2, 2021 (Zoom Webinar). Presentation (html)

An example of the kickback illusion

Rectangles appear to wobble when caught in vertical lines, though they are in constant velocity motion.

Howe, P. D. L., Thompson, P. G., Anstis, S., Sagreiya, H., & Livingstone, M. S. (2006). Explaining the footsteps, belly dancer, Wenceslas and kickback illusions. Journal of Vision, 6, 1396–1405. doi: 10.1167/6.12.5

Kitaoka, A. & Anstis, S. (2021). A review of the footsteps illusions. Journal of Illusion, 2, #5612, 1-22. PDF --- Website --- https://doi.org/10.47691/joi.v2.5612 --- Movies and figures

"Entangling illusion"

Two concentric circles appear to be entangled.

extinction illusion

Ninio's type
Ninio, J. & Stevens, K. A. (2000). Variations on the Hermann grid: an extnction illusion. Perception, 29, 1209-1217.

classic geometrical illusions

Classic geometric illusions (late 19th or early 20th century)
(a) Müller-Lyer illusion: The lower horizontal line segment appears to be longer than the upper one, though they are the same length.
(b) Ebbinghause illusion: The circle surrounded by smaller ones appears to be larger than the circle of the same size surrounded by larger ones.
(c) Ponzo illusion: The two lines or circles are the same size, but the one nearer to the apex appears to be larger than the other.
(d) Poggendorff illusion: The upper-right line segment appears to lie above the extension of the lower-left one, but they are actually aligned.
(e) Zöllner illusion: Oblique black lines appear to tilt alternately.
(f) Hering illusion: Horizontal straight lines appear to curve outward.
(g) Münsterberg illusion (Café Wall illusion): Gray lines are horizontally drawn, but they appear to tilt alternately.
(h) Fraser illusion: Parallel rows made up of short obliques appear to tilt alternately depending of the tilts of the obliques.
(i) Fraser's spiral illusion: Concentric circles appear to be spirals.

Color illusions

Helmholtz-Kohlrausch effect

Colors of higher saturation appear to be brighter.

isoluminance Y = 0.213, saturation of red (placed at 3 o'clock) = 1.0, saturation of the other colors = 0.5

isolumimance Y = 0.072, saturation of blue (placed at 7 o'clock) = 1.0, saturation of the other colors = 0.5

Red appears to be brighter than white, though the luminance of the former is lower than the latter.

Confirm it!
Eyedropper tool　<August 1, 2, September 16, October 8, 9, 2022>

cf.

A program to plot pixel colors in the CIE Yxy color space <June 6, 19, 20, 21, 24, 26, August 14, 2022>

Munker illusion

"Blue and green spirals"

There appear to be bluish spirals and greenish ones, though they are the same color (r = 0, g = 255, b = 150).

Munker illusion

Red-purple rectangles and orange ones appear to be embedded in the upper-left block and the upper-right one, respectively, though they are the same red. Bluish-green rectangles and yellowish-green ones appear to be embedded in the lower-left block and the lower-right one, respectively, though they are the same green.

Munker, H. (1970) Farbige Gitter, Abbildung auf der Netzhaut und übertragungstheoretische Beschreibung der Farbwahrnehmung. München: Habilitationsschrift.

The Munker effect can be described in terms of color assimilation and color contrast.

I will explain the Munker illusion in the context of spatial color mixing.

What is white? What is black?

"White or black composed of RGB"

The hair and clothes in the left image appear to be whitish and those in the right one appear to be blackish, though they are the same RGB (red, green and blue) stripes.

Enlarged image