A talk on visual illusion

August 18, 2022, 11:00 am - (online)
for L'Oreal

Akiyoshi Kitaoka (Ritsumeikan University) email

since August 11, 2022

Introduction

Here 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.

A variety of visual illusions

"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

"An expanding blue ellipse 3"

A blue ellipse appears to expand.

"Rotating snales"

Disks appear to rotate.

version 2015

"Drifting Gabor patches illusion"

The inset/surround appears to move.

"Swaying heart"

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

"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

Differences in perceived speed and a Shinkansen pic.twitter.com/fK29D2guVu
— Akiyoshi Kitaoka (@AkiyoshiKitaoka) September 6, 2021

http://www.psy.ritsumei.ac.jp/~akitaoka/saishin61.html

"Entangling illusion"

Two concentric circles appear to be entangled.

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.

"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).

"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

Original image

Movie demo

cf.

"White and black"

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 luminance.

"Illusory yellow halo"

Illusory yellow is observed outside the hearts, but the color is white.

enlarged image

"Illusory yellow"

Illusory yellow is observed in the lower-right disk, but the color is white.

expanded image

Original image

Illusory yellow is perceived. pic.twitter.com/8jgjQglo0v
— Akiyoshi Kitaoka (@AkiyoshiKitaoka) June 12, 2021

Let's assume you have no yellow pen. Can you draw yellow?

You can!

Let's assume you have no reddish pen. Can you draw a reddish object? Yes, you can!

"Illusory reddish coke can"

"Eye color illusion"

Eyes appear to be reddish, yellowish, greenish and bluish, though they are gray as shown below.

(γ = 1.2, α = .48)

Strawberries appear to be reddish, though each pixel is cyan hue.

(γ = 1.2, α = .48)

Strawberries appear to be bluish, though each pixel is yellow hue.

Web (JavaScript) program for histogram compression (color illusion creater) ver. ECVP2021 ShowTime!

How to use it (on Twitter)

My latest book explains how to use the program. (written in Japanese)

amazon

Today's main topic:
"Skin color change" and illusory blue

Color illusion creater: a web (JavaScript) program for histogram compression ver. ECVP2021 ShowTime!

"+" shows the white point (D65).

cf.

cf. The original image

Skin color and the vein color illusion (illusory blue)

Veins appear to be bluish or greenish, though the pixels are yellow or orange hue and close to gray.

part of the photo shown above

The apparent vein color quite resembles the illusory blue of the car image

Therefore, I suggest that the perception of skin color might be based on the same mechanism as the perception of the image of the illusory blue car. That is, perceptual transparency accompanied by color constancy plays an important part.