| Mr.
Angry and Ms. Calm Distance changes face perception? ) |
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| This
is probably one of the best illusions ever! Please do the following:
look at the above images from your seat in front of the computer;
Mr. Angry is on the left, and Ms. Calm is on
the right. Now, get up from your seat, and move back 10 or 12
feet. Who’s
the angry and calm now? This illusion was made by Phillippe G. Schyns and Aude Oliva. |  |
| Comment: This striking illusion helps us understand the role of the neuronal brain mechanism for size constancy in visual perception. I don’t know what the creators of the illusion would say, but this is how it seems to me. The two images are each composed of two facial expressions, namely *calm* and *angry*. However, in the face on the left the angry features are composed of high spatial-frequency components, and the calm features are composed of low spatial-frequency components. For the face on the right, calm is expressed by high spatial-frequency features and angry is low frequency. If we view the two faces from a distance of 1 foot, the high-frequency features dominate so the left face is angry while the right face is calm. If we view the faces from a distance of 10 feet, the low-frequency features dominate so the left face is calm while the right face is angry. This all happens because the size-constancy mechanism in the visual system expands the brain’s representation of the faces to compensate as their retinal size contracts tenfold when we move back from a 1-foot view to a 10-foot view. As this happens, visual resolution is degraded with the increase in viewing distance, and the low-frequency features become dominant. Hence the switch in facial expression. For a detailed neuronal model of the brain’s putative size-constancy mechanism see *The Cognitive Brain*, pp. 89-93. If there is another explanation for this illusion, I would very much like to see it. —Arnold Trehub |
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