The Coyote Illusion: Motion Blur Increases Apparent Speed

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

(© 2013 Alan Ho and Stuart Anstis)

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 Leaning Tower Illusion

2007 First prize
Frederick Kingdom, Ali Yoonessi and Elena Gheorghiu

McGill University, Canada

© 2007 Kingdom, Yoonessi & Gheorghiu

Here is a novel illusion that is as striking as it is simple. The two images of the Leaning Tower of Pisa are identical, yet one has the impression that the tower on the right leans more, as if photographed from a different angle. The reason for this is because the visual system treats the two images as if part of a singlescene. Normally, if two adjacent towers rise at the same angle, their image outlines converge as they recede from view due to perspective, and this is taken into account by the visual system. So when confronted with two towers whose corresponding outlines are parallel, the visual system assumes they must be diverging as they rise from view, and this is what we see. The illusion is not restricted to towers photographed from below, but works well with other scenes, such as railway tracks receding into the distance. What this illusion reveals is less to do with perspective, but how the visual system tends to treat two side-by-side images as if part of the same scene. However hard we try to think of the two photographs of the Leaning Tower as separate, albeit identical images of the same object, our visual system regards them as the ‘Twin Towers of Pisa’, whose perspective can only be interpreted in terms of one tower leaning more than the other.

Leaning tower illusion Frederick A. A. Kingdom, Ali Yoonessi, Elena Gheorghiu Scholarpedia 2007. 2(12):5392.

The Leaning Tower illusion: a new illusion of perspective Frederick A. A. Kingdom, Ali Yoonessi, Elena Gheorghiu Perception. 2007. 36(3):475-477

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