* Illustration: Marc Johns * 1 // They listen to the crowd. Researchers asked two sets of soccer refs to judge game clips. One group watched the footage on mute; the other with sound. The refs who heard the fans called 15.5 percent fewer fouls against the home team. So, yeah, screaming like a maniac really does help.

2 // They aren't blind, but they are seeing things. To compensate for a 100-millisecond lag in our visual system, our brain creates an illusion that shifts objects in the direction they're traveling. So a tennis ball flying toward the baseline may appear to cross it before it bounces just inside. This, according to vision scientists, explains 70 of 83 bad calls made during the 2007 Wimbledon Championships.

3 // They prefer red. Tae kwon do officials scoring fighters on film gave more points to those wearing red than blue. When asked to review the same footage after the uniform colors were digitally switched, they again ruled in favor of red. Pow!

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