For many sports, performance is all about hitting a target: striking a ball with a bat, placing a golf or soccer ball in just the right spot, etc. A common refrain among athletes who have had a successful performance is that those targets seemed large—they perceived the ball as huge, the goal mouth as enormous. Now, some researchers have found that these perceptions work the other way around, too. By making a target look larger or smaller than it actually was, they could change the performance of golfers.
The experiment was pretty simple. The authors set up a small putting green with a hole that was 5cm in diameter. They then projected a series of circles surrounding the hole. When the circles were larger than the hole, it was perceived as smaller; when they were smaller, participants thought the hole was larger. And this made a big difference. Putting performance with the perceptually larger hole was about double that when the golfers were made to think the hole was smaller.
The authors use their discussion to consider whether this suggests that slumps and hot streaks are matters of changes in perception. But they get to their real (and currently relevant) thought in the introduction: they like going to college basketball games and watching the home crowd attempt to distract the visitors during free throws. It's possible that, in coming up with an effective optical illusion, they've given attentive college students a new recipe for doing so.