IDW 2019 "A variety of visual illusions"

IDW' 19, Sapporo Convention Center, Sapporo, Japan
18:30-18:50 Wednesday, November 27, 2019 @Mid-sized Hall A

A variety of visual illusions

Akiyoshi KITAOKA, Psychology, Ritsumeikan University, Osaka, Japan email

since November 9, 2019 Handout 1 - Handout 2

Shape illusion

"Entanglement illusion"

kind of the spiral illusion of the Popple illusion (phase-shift illusion)

Two concentric rings appear to be entangled.

Illusory motion in the direction of a particular pattern arrangement

"Rotating snakes"

Each disk appears to rotate 'spontaneously' in the constant direction, from black to blue, white, yellow, back to black.

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.

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.

Illusion occurs with red and blue.

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

Motion illusion accompamied by tilt illusion

The inset appears to move depending on smooth motion of retinal images.

"Drifting Emboss illusion"
(sine type)

The inset appears to move.

"Drifting spines illusion"

The inset appears to move. The inset is a square but verticals appear to tilt clockwise and horizontals appear to tilt clockwise.

"Illusion of Y-junctions"

The inset appears to move.

Explanation

I attribute this coexistence to 4-stroke motion and 4-stroke tilt illusion.

Kitaoka, A. (2010). The Fraser illusion family and the corresponding motion illusions. 33rd European Conference on Visual Perception (ECVP 2010), EPFL, Lausanne, Switzerland, 2010/8/22-26, 8/26 poster publication. Poster （Kitaoka, A. (2010) The Fraser illusion family and the corresponding motion illusions. Perception, 39, Supplement, #61, p. 178）

In each gray square, the middle line or edge appears to tilt counterclockwise.

Motion illusion based upon the difference in visual delay

Enhanced version of the fluttering heart illusion

When retinal images are moved, hearts appear to move.

"Heart"

The heart appears to swing when the image is swayed.

"Kitaoka's publication"

Books appear to move when the image is swayed.

Motion illusion triggered by some eye movement

Illusory motion is triggered by eye movement, blinks, or some events along the direction orthogonal to stripes.

"Pack of rotating red snakes"

Rings appears to rotate slowly or quickly.

"Hatpin urchin (pink)"

The image appears to wiggle in the radial direction.

"The sun in summer"

The center appears to be bright and the image appears to wobble.

Lightness illusion

"Illusory light therapy 2018"

"Suns" appear to shine.

Induced-color illusion

"Illusory yellow spirals"

Color illusion based upon color constancy

(γ = 1.2, α = .48)

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

"Akiyoshi Kitaoka with an illusory reddish face"

The face appears to be reddish, though the pixels are green-bluish (cyan hue).

"Akiyoshi Kitaoka with an illusory bluish face"

The face appears to be bluish, though the pixels are skin color (yellowish orange).

"Vein color illusion"

Veins appear to be bluish, though they are not.

"Applied vein color illusion"

The train cars appear to be bluish, though the pixels are yellowish.

"Eye color illusion"

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

The hypothesis of "histogram equalization" proposed by Shapiro et al. (2018) can explain these phenomena.

Shapiro, A., Hedjar, L., Dixon, E., and Kitaoka, A. (2018). Kitaoka's tomato: Two simple explanations based on information in the stimulus. i-Perception, 9(1), January-February, 1-9. PDF (open access)

Lightness illusions based upon spatial color mixture

Additive color mixture image (left) and subtractive color mixture image (right)

"White and black with RGB"

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

Expanded image

Movie demo

Standard color mixture with three elemental colors

(R: red, G: green, B: blue, C: cyan, M: magenta, Y: yellow, K: black, W: white)

Spatial color mixture with three elemental color subpixels

Spatial color mixture with six subpixels

Lightness illusion based upon lightness constancy

↓Achromatic multiplicative color change (left) and achromatic additive color change (right)↓

The hair and clothes in the left image appear to be whitish whereas those in the right one to be blackish, though they are the same luminance.

Color illusion (Munker illusion)

"Green and blue spirals"

There appear to be spirals of light green or light blue. Actually, they are identical (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.

"Magenta heart and orange one"

The heart in the left image appears to be red-purple (magenta) whereas that in the right one to be orange, though they consist of the same red stripes.

This color illusion (Munker illusion) may be closely related to the perception of spatial color mixture. Please visit my booth.

Akiyoshi's illusion pages