The Disappearing Faces Illusion

Stuart Anstis
University of California, San Diego, USA

In the movie the test stimuli were two transparently superimposed, low-contrast greyscale photos. We used one photo of Albert Einstein and one of Marilyn Monroe. Two identical Einstein+Marilyn photos were set up side by side with a fixation point between them; each looked like a confused jumble, and neither face could be seen clearly. The adapting stimuli were high-contrast flickering versions of the two single components: Einstein on the left and Marilyn on the right. Result: Adaptation made Einstein fade out subjectively from the left- hand Einstein+Marilyn, which now looked like Marilyn. Conversely, Marilyn subjectively faded out from the Einstein+Marilyn on the right, which now looked like Einstein. This adaptation selectively picked out (and degraded) the test photo with which it was congruent, and had little effect on the other, superimposed but noncongruent test photo.

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The Coyote Illusion: Motion Blur Increases Apparent Speed

Alan Ho and Stuart Anstis
Ambrose University College, Canada, and UC San Diego, USA

Cartoonists are known to use multiple illustrative techniques to depict fast moving objects. In the Road Runner and Wile E. Coyote Show, for example, cartoonists drew multiple numbers of feet, usually streaky and blurred inside distorted loops under the cartoon characters’ torsos to symbolize rapid motion. Our illusion demonstrates that the perceived speed of objects can go twice as fast as their actual speed when objects getting blur while that are revolving rapidly in circular paths. This finding supports the view that the human brain uses many strategies to estimate speed of moving objects in the environment.

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The colored dot/peripheral vs. central vision

Stuart Anstis
UC San Diego, USA

You will see that the spots move along straight horizontal paths. But now look at it in peripheral vision – look away, but attend to the movie out of the corner of your eye. The paths of the spots now appear to be bent, in the direction of the background stripes. In this example, the spots move around in a circle. But in peripheral vision they appear to slide vertically when the background stripes are vertical, and horizontally when the stripes are horizontal.

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Attention-induced motion displacement

Peter Tse, Patrick Cavanagh, David Whitney & Stuart Anstis
Dartmouth College, USA, UC San Diego, USA, Université Paris Descartes, France

Fixate the blue dot.
When you attend to the whole white layer”s motion, the red dots appear to be slanted to the right.
When you attend to the whole black layer”s motion, the red dots appear to be slanted to the left.

When you don”t attend to either layer, the dots are aligned vertically, which they in fact are in every case.

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Illusions from rotating rings

Stuart Anstis & Patrick Cavanagh
UC San Diego, USA, Université Paris Descartes, France

A rotating figure 8 made of two overlapping rings is ambiguous. Small spots painted on the rings can resolve the ambiguity, forcing them to look like an 8 or like 2 rings. Even without any spots, if the brightness of the intersections where the rings overlap makes the rings look transparent, they slide. If not, they stick.

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