“For skills to improve, we must update an existing memory with new information,” the researchers conclude. If you practice the exact same thing the exact same way every time, you’re not layering much new knowledge over what you already know.

But, the theory goes, subtly changing things up and adding tension between what your body already knows and what it doesn’t can help you learn skills faster.

The researchers caution that it’s important not to change things up toomuch. If you’re trying to improve your golf swing and spend 20 minutes a day shooting hoops, you’re probably not doing yourself any favors. “If you make the altered task too different, people do not get the gain we observed,” Celnik said. “The modification between sessions needs to be subtle.”