I heard this story on NPR the other day talking about a study where they looked at golfers and found that golfers who were playing better perceived the hole to be larger, and those that did were not playing as well saw the hole as smaller. By creating an optical illusion and altering their perception of the hole, the researchers were able to change a golfer's putting.
It's good food for thought, not only about golf, but for marketing as well. Here's a link to the story.
Can You Think Your Way To That Hole-In-One? by Joe Palca.