Thursday, November 29, 2012

Pickpockets and Saccades

Did you ever wonder how a pickpocket manages to pick a pocket, even in a magic show for example when you, the volunteer, knew you were going to be pickpocketed? Turns out a pickpocket is successful only when he moves his free hand in an arc instead of a straight line. It has to do with saccades, eye movements that are among the fastest movements made by the human body and that precede conscious decisions about where to focus one’s gaze. Generally, eyes are quicker than hands. When you see a hand moving in a straight line, your eyes automatically move toward the end point. See a hand moving in an arc, however, and your eyes cannot predict where the arc is going to end. The arc shape seems to interfere with your saccades. The consequences? You tend to fixate on the hand itself, which prevents you from noticing that the pickpocket’s other hand is reaching somewhere else, into your pocket, for instance.

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