If a basketball player is flummoxed by his foul shooting, he might turn to a Stanford professor for a little solace.
Experiments on rhesus monkeys by Stanford electrical engineering professor Krishna Shenoy suggest that the brain may not be wired to duplicate the same movements time after time.
Mr. Shenoy and his colleagues trained the monkeys to reach either quickly or slowly to touch a dot on a computer screen, depending on its color, to get a juice reward.
The experimenters measured not only the monkey's muscle movements, but the activity of their brains before they made their moves. They discovered that about half the variations in the monkey's movements were caused by muscle problems, and half were caused by the brain's neurons firing in different patterns before the motions.
"Let's say you're at the free-throw line, and you know you want to extend your hands in the same way and release the ball at the same point each time, but the real problem is the speed with which you do that," Mr. Shenoy said.
"You're trying your very best to reach that exact speed each time, but our experiments show the brain doesn't always permit that."
One possible reason is that our brains may have evolved to be flexible.
"It could well be we evolved because we mostly have to confront novel situations with a huge variability in how we need to move," Mr. Shenoy said.
"As fans," he said, "we tend to overly focus on the fact that players can't make all their free throws, but what's amazing is that they make any of them at all, and even more so, that they can make all these shots from all over the court."