Vision Sciences Stuff -- the skinny on a new illusion

This week I’m attending the annual meeting of the Vision Sciences Society in Naples Florida. Every day or so, I’ll post about a subset of the cool, interesting, funny, or quirky (I won’t say which) talks/posters I happened to catch. You can read the first installment here. Here’s a fun one from my University of Illinois colleague Diane Beck.

“Why women wear heals: A new size illusion?” by Diane Beck, Barbara Emanuele, and Silvia Savazzi. This study looks at why tall people sometimes look thinner than short people of comparable girth and also looks to see whether thin people look taller. The task was simple: view two stimuli and judge which is wider (or taller). On most trials, the stimuli differed in width, but on critical trials they were actually identical on the judged dimension. Look at the image below — the tall figure looks skinnier even though the two are exactly the same width.

Which body looks skinnier? They're actually identical in width.

When the stimuli have the same width, people should pick at random — there is no correct answer. Yet, people judge the taller one to be skinnier more than 80% of the time. They also judged skinnier bodies to be taller more than 70% of the time. The clinching experiments showed that the effect is a more general illusion rather than some bias about person perception: People judge a taller rectangle to be narrower nearly 70% of the time and a narrow rectangle to be taller nearly 60% of the time. Apparently, being tall makes you look thin, so those of you who are trying to lose some weight just need to try being taller instead.

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