[The following is an exact transcript of this podcast.]

The eyes often don’t have it. Tennis referees, for example, sometimes mess up when calling a ball in or out. And a new study finds that refs are much more likely to make a mistake by calling a good ball out than by calling a bad ball in. The research is in the October 28th issue of the journal Current Biology.

It takes at least a tenth of a second for us to become aware of an image striking the retina. So we all have to construct our perception of moving objects. And the way the brain works, we consistently think something has gone slightly further than it really has. It’s not surprising then that we misjudge the position of hundred-mile-an-hour tennis balls.

When researcher David Whitney saw a call overturned during Wimbledon, he decided to check out referee error rates. He reviewed videos of more than 4,000 randomly selected tennis points, and found 83 incorrect calls. Seventy of the 83 were the type predicted. So players contesting calls are better off asking for reviews on their own shots called out than their opponent’s called in.

—Steve Mirsky 

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