USA – A Bucknell University professor led researchers in an explanation as to why a curveball in baseball breaks so much when seen by a batter. Their imagery won them Best Illusion of the Year for 2009 by Vision Sciences Society.

Dr. Arthur G. Shapiro, of the Department of Psychology at Bucknell University (Lewisburg, Pennsylvania), along with Zhong-Lin Lu, Emily Knight and Robert Ennis (University of Southern California, Dartmouth College, and SUNY College of Optimetry, respectively) won the 2009 award for the Best Illusion of the Year at a meeting of the Vision Sciences Society.

The 2009 contest was held on May 10, 2009, at the Naples Philharmonic Center, in Naples, Florida, during the week of the Vision Sciences Society conference.

Their demonstration, called “The break of the curveball,” explains why a baseball pitcher’s curve ball seems to break so much as it is thrown toward a batter.

The physics of a baseball states that it curves because of the topspin put on the ball. It curves gradually during its flight toward the batter’s box by a couple of feet.

However, for a player standing in the batter’s box, it seems to be going straight during the first part of its flight but then jumps several feet, later on, almost instantaneously.

Why does its trajectory appear to change so abruptly to the batter?

The animation provided by the Shapiro team illustrates why the batter sees an abrupt change in the ball.

The Shapiro team animation is shown on the website IllusionContest.

The animated baseball, at the website, is spinning and, also, falling vertically. When you look at it directly (with your central system, like a batter would see it coming off of the pitcher) it appears to be moving straight down.

However, when you look at it out of the corner of your eye (looking directly at the blue dot), then it appears to be moving at an angle. When a batter looks at the ball with his or her peripheral vision, it appears to move to the side.

The website states, “In baseball, a curveball creates a physical effect and a perceptual puzzle. The physical effect (the curve) arises because the ball’s rotation leads to a deflection in the ball’s path. The perceptual puzzle arises because the deflection is actually gradual but is often perceived as an abrupt change in direction (the break).”

And, “Our illusions suggest that the perceived “break” may be caused by the transition from the central visual system to the peripheral visual system. Like a curveball, the spinning disks in the illusions appear to abruptly change direction when an observer switches from foveal (central) to peripheral viewing.”

Thus, when the spinning ball is seen moving directly in front of one’s eyes (using our central visual system), it appears to move in a straight line.

However, eventually it is seen out of the corner of one’s eye (using our peripheral visual system), as if standing sideways in the batter’s box, and the spin of the ball makes the ball appear as if it is curving. The batter sees the ball leave the pitcher’s fingers with the central system, but as it gets closer to the plate, the peripheral system takes over.

Somewhere along the trajectory of the ball, the changeover from the central visual system to the peripheral visual system appears to make the ball suddenly change its flight path.

It suddenly jumps. Oftentimes, it’s the ultimate demise of the unwary batter.

Photo courtesy of illustrationsof.com

This article was written by William Atkins/iTWIRE

Tags: Feature