Our brains respond to our shadows as if they were another part of the body, according to a scientific study. When we see something about to come into contact with the edge of our shadow, brain activity suggests it is as if they are about to touch us instead. Scientists tested volunteers' reaction speeds and accuracy while distracting them with flashing lights. They found that similar errors happened when lights flashed either next to a hand's shadow or the hand itself. The brain develops an internal “map” which helps it define exactly where the body is—which helps it navigate around the world outside.
The results, by researchers at Royal Holloway College in London, suggest that the body's shadow may form part of that map. The tests used shadows cast onto a white table in front of a seated volunteer. The subject was asked to distinguish between touches on the thumb and forefinger of the hand, and the number of errors—and the overall reaction time—were recorded. When flashing lights placed near the hand are activated, the number of errors rises and reaction time slows as the brain is forced to deal with the distraction.