Human visual system not trained to handle spinning balls, says psychologist

LONDON: Football goalkeepers and baseball catchers, who miss spinning balls coming their way, cannot be held responsible this lapse as new research has shown that humans cannot normally anticipate the spinning balls’ trajectory.

A psychologist in Northern Ireland, Cathy Craig, who studied the ability of athletes to follow the path of spinning balls, has found that the human visual system is not equipped to track the curved course of a fast-spinning ball. Craig of Queen’s University in Belfast reported her findings in New Scientist magazine.

She said she was motivated to examine the ability of humans in following the course of a spinning ball after witnessing a 1997 soccer game in which Roberto Carlos scored a goal for Brazil.

“Everybody seemed to think it was going wide,” she told the magazine. “Then it curved in at the last minute.”

She said she asked professional players watching a virtual game to forecast whether a ball with a spin of 600 revolutions per minute would land in the goal. None of them could predict the trajectory of the ball.

Craig says spin produces a force that adds to the speed of the ball in such a way that human eyes cannot process the movement of the ball. She has a reason: spinning is not a natural process and human visual capacity is not equipped to detect its course.

 

She is of the opinion that many top players work hard at trying to develop cognitive and behavioural compensatory strategies in order to counteract this shortcoming.

She says humans can predict how gravity will affect a body in motion and get ahead of it. But, a curveball or spinner involves a Magnus force pushing it sideways — a feature that does not happen in nature — and hence the human eyes and minds are not trained to handle them.