Live from VSS: When you make a bad tennis shot, the ball seems faster

Posted by Dave on May 11, 2010 | 2 Comments

Pro golfers say the hole seems bigger when they’re putting well. Baseball players say the ball seems bigger when they’re hitting well. But what about the perceived speed of the baseball?

Today at the VSS (Vision Sciences Society) conference I saw a great poster where the researchers measured real-world perception of the speed of a tennis ball. Mila Sugovic and Jessica Witt asked players enrolled in beginning, intermediate, and expert tennis lessons to return balls launched by a serving machine at 50 to 80 miles per hour. After each shot, the players walked to a computer showing an animated ball moving toward them. They pressed a button to launch the ball, and again after they estimated the ball had been in the air for the same amount of time as the ball they had just hit.

Did the advanced players see the ball as moving slower than the beginners? Actually, the ability of the players didn’t predict their estimates. But when the players made a better shot, they saw the ball as taking more time to get to them.

Sugovic and Witt videotaped each shot and measured the actual time the ball took to travel to the players. They compared this to the players’ estimates. In general, players overestimated the speed of the balls, saying they took about 70 percent as long in the air as they actually did. But when players subsequently hit the balls out of bounds, their estimates of ball speed were significantly faster than when they hit a good shot. The difference in perception corresponded to about a 5 mile-per-hour difference in speed.

After the study was over, the researchers also asked players to estimate the height of the net. Players who had hit more shots into the net were significantly more likely to make higher net-height estimates!

Sugovic, M., & Witt, J. (2011). Performance affects perception of ball speed in tennis. Poster presented at Vision Sciences Society meeting, Naples, FL.

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