Key to Barry Bonds' success is eyeing the ball

By Corey Binns

updated 1:51 p.m. ET July 23, 2007

Barry Bonds has his eyes on home-run history, but exactly why some pros excel at keeping their eyes on the ball has remained a baseball marvel until now.

Deciphering curveballs from fastballs and balls from strikes requires that a player's eyes precisely lock onto the ball, as described in recently published research on humans' ability to track balls and other moving objects.

"Our results show that individuals vary tremendously in this ability to lock their eyes onto a moving object, called smooth pursuit, and that this variation relates strongly to a specific type of motion perception ability, so-called high-level motion perception," said study co-author and University of Pennsylvania cognitive psychologist Jeremy Wilmer.

Tracking bodies in motion
Humans use two skills to see bodies in motion. First, our eyes first need to catch up to a moving object, a skill called low-level motion perception, when we sense something fluttering before we can recognize exactly what it is. Next, high-level motion perception occurs, at which point our eyes lock on, identify and examine the object.

Wilmer and his colleagues conducted two tests on the low- and high-level motion perception abilities of 45 participants. In one test, study participants were unable to move their eyes and had to describe the speed at which they saw objects zooming by. The second test tracked the movement of people's eyes and measured their ability to follow moving objects.

Some volunteers excelled at low-level motion perception and easily caught up to a moving object with their eyes—they perceived motion more quickly out of the starting block. Meanwhile, a different group of volunteers exhibited more skill at high-level motion perception and were better at locking onto a moving target once their eyes caught up to it (smooth pursuit).

The two different aspects of perceiving motion drive different stages of smooth pursuit, Wilmer said.

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