The peripheral drift illusion (PDI) refers to a

motion illusion The term illusory motion, also known as motion illusion, is an optical illusion in which a static image appears to be moving due to the cognitive effects of interacting color contrasts, object shapes, and position. Apparent motion is the most co ...

generated by the presentation of a sawtooth luminance grating in the visual periphery. This illusion was first described by Faubert and Herbert (1999), although a similar effect called the "escalator illusion" was reported by Fraser and Wilcox (1979). A variant of the PDI was created by

Kitaoka Akiyoshi is a Professor of Psychology at the College of Letters, Ritsumeikan University, Kyoto, Japan. In 1984, he received a BSc from the Department of Biology, University of Tsukuba, Tsukuba, Japan, where he studied animal psychology (burrowing behavior ...

and Ashida (2003) who took the continuous sawtooth luminance change, and reversed the intermediate greys. Kitaoka has created numerous variants of the PDI, and one called "rotating snakes" has become very popular. The latter demonstration has kindled great interest in the PDI. The

illusion An illusion is a distortion of the senses, which can reveal how the mind normally organizes and interprets sensory stimulation. Although illusions distort the human perception of reality, they are generally shared by most people. Illusions may ...

is easily seen when fixating off to the side of it, and then blinking as fast as possible. Most observers can see the illusion easily when reading text with the illusion figure in the periphery. The motion of such illusions is consistently perceived in a dark-to-light direction. Two papers have been published examining the neural mechanisms involved in seeing the PDI (Backus & Oruç, 2005; Conway et al., 2005). Faubert and Herbert (1999) suggested the illusion was based on temporal differences in

luminance Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls withi ...

processing producing a signal that tricks the motion system. Both of the articles from 2005 are broadly consistent with those ideas, although contrast appears to be an important factor (Backus & Oruç, 2005).

Rotating snakes

Rotating snakes is an optical illusion developed by Professor

Akiyoshi Kitaoka is a Professor of Psychology at the College of Letters, Ritsumeikan University, Kyoto, Japan. In 1984, he received a BSc from the Department of Biology, University of Tsukuba, Tsukuba, Japan, where he studied animal psychology (burrowing behavior ...

in 2003. A type of peripheral drift illusion, the "snakes" consist of several bands of color which resemble coiled serpents. Although the image is static, the snakes appear to be moving in circles. The speed of perceived motion depends on the frequency of microsaccadic eye movements (Alexander & Martinez-Conde, 2019).

Gallery

Image:primrose_field_peripheral_drift_illusion.svg, Illusion similar to ''Primrose Field'' by Kitaoka Akiyoshi Image:Anomalous_motion_illusion1.svg, A peripheral drift illusion by Paul Nasca Image:Peripheral_drift.png, A peripheral drift illusion by Paul Nasca Image:Dualing Illusions.svg, Combination of a Café wall illusion and a horizontal peripheral drift illusion Image:Sunburst_peripheral_drift_illusion_fixed.svg, A peripheral drift illusion giving a throbbing effect

References

Inline citations

General references

*Faubert, J. & Herbert, A.M. (1999)
The peripheral drift illusion: A motion illusion in the visual periphery.
Perception, 28, 617–622. *Fraser, A., Wilcox, K.J. (1979). Perception of illusory movement. ''Nature'', 281, 565–566. *Kitaoka. A., Ashida. H. (2003). Phenomenal characteristics of the peripheral drift illusion. Vision, 15, 261–262. *Backus, B.T. & Oruç, İ. (2005). Illusory motion from change over time in the response to contrast and luminance. Journal of Vision, 5(11), 1055–1069

. *Conway, B.R., Kitaoka, A., Yazdanbakhsh, A., Pack, C.C., Livingstone, M.S. (2005). Neural basis for a powerful static motion illusion. Journal of Neuroscience, 25, 5651–5656. *Alexander, R. G.; Martinez-Conde, S (2019). "Fixational eye movements". Eye Movement Research. Springer, Cham, 104–106,

External links

Rotating snakes
at Akiyoshi's illusion pages

at Sarcone's optical illusion pattern page
These patterns move, but it’s an illusion
by Smithsonian Research Lab
Does your pet see Peripheral drift?
a slideshow designed for testing on animals {{Optical illusions Optical illusions Vision