Winning by spinning

Cathy M Craig and her team of researchers at Queen’s University in Belfast, Northern Ireland, have concluded that predicting the effects of lateral acceleration on such a ball’s trajectory is a Herculean task.

“Our study shows that the human visual system is poorly equipped with the mechanisms necessary to judge where balls with spin will go. This would suggest it is advantageous for players to add spin to try and dupe the goalkeeper,” Craig said.

Eleven professional footballers — attackers, midfielders and defenders — and nine goalkeepers from clubs like AC Milan, Olympique Marseille and Bayer Leverkusen were asked to judge whether a range of simulated free-kicks would end up in the goal, using a virtual reality system.

In the absence of spin, balls were consistently judged to be entering the goal. But the ace footballers were stumped when spin came into play, misjudging the future arrival point of such free-kicks. The study was published in this month’s Natur Wissenschaften journal, just days before the World Cup kicks off.

According to Craig, though the new study found that perceptual weaknesses in judging free-kicks with spin can’t be trained away, all is not lost for the goalkeepers. “In terms of pure perception, I don’t think it is possible to improve. But players can use higher cognitive strategies to help them make educated guesses about where the ball is going,” she said.

Also, the person striking the ball could give goalkeepers an indication.

“For example, David Beckham tends to add top spin to the ball causing it to dip more than expected during the trajectory. Roberto Carlos adds sidespin that bends the ball back in again. Also, by strategically placing the defensive wall, goalkeepers can force the player to kick the ball in a certain direction,” she said. Craig feels that professional footballers and teams are keen to gain from the spin trick, capitalising on defensive errors to seize free-kick opportunities.

–Tony Tharakan