IMAGES: Tricks of the Light

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Science  28 Mar 2003:
Vol. 299, Issue 5615, pp. 1957c
DOI: 10.1126/science.299.5615.1957c

To learn how the brain works, neurobiologists such as Dale Purves of Duke University Medical Center try to dupe it. These 16 animations, from Purves's lab use illusions to explore how factors such as orientation, lighting, contrast, and background shape our visual perception. Above, for example, the central squares on the front and top face of the cube are the same shade of brown, but they can appear yellow, depending on how much light seems to be hitting the face. Background articles provide in-depth explanations for each visual trick.

OK, so we're suckers for subtle illusions, but surely we'd notice if a gorilla shambled into the room. Maybe not, as these short movies from the Visual Cognition Lab at the University of Illinois, Urbana-Champaign, demonstrate. (The flicks are about halfway down the page.) Concentrating on one demanding task, such as tallying the number of passes a basketball team tosses, can make you oblivious to even bizarre events within your field of vision. The phenomenon, called inattentional blindness, might explain why drivers blathering on cell phones are more likely to get in accidents.

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