Baseball Science

With the World Series coming up, it’s more important than ever – In baseball, we’ve often told you how sports and science are entangled, and here’s another way: New research suggests that no pitcher can make a curveball “break” or a fastball “rise,” it’s all an optical illusion.

The term “breaking ball” describes an apparent sudden drop or other change in trajectory as the ball nears home plate. That, researchers say, is an illusion. Researcher Arthur Shapiro says, “The curveball does curve, but the curve has been measured and shown to be gradual. It’s always going to follow a parabolic path. But from a hitter’s point of view, an approaching ball can appear to break, drop or do a whole range of unusual behaviors.” He and fellow researcher Zhong-Lin Lu have also demonstrated how an object falling in a straight line can seem to change direction.

Batters tend to switch from central to peripheral vision when the ball is about 20 feet away, or two-thirds of the way to home plate. The eye’s peripheral vision lacks the ability to separate the motions of the spinning ball. In particular, it gets confused by the combination of the ball’s velocity and spin. The result is a gap between the ball’s trajectory and the path as perceived by the batter. The gap is small when the batter switches to peripheral vision, but gets larger as the ball travels the last 20 feet to home plate.

As the ball arrives at the plate, the batter switches back to central vision and sees it in a different spot than expected. That perception of an abrupt change is the “break” in the curveball that frustrates batters. Lu says, “Depending on how much and when the batter’s eyes shift while tracking the ball, you can actually get a sizable break. The difference between central and peripheral vision is key to understanding the break of the curveball. A similar illusion explains the ‘rising fastball.'”

The obvious remedy for a batter, repeated by parents and coaches everywhere, is to “keep your eye on the ball.” You also need plenty of good luck to win (NOTE: Subscribers can still listen to all Anne Strieber’s Mysterious Powers shows).

Art credit: Dreamstime.com

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