What the study, published last week in the online journal Cerebral Corex, revealed was that the movement-control areas of the brain called the "mirror system" were activated in the dancers when they saw a movement they had themselves performed.

The non-dancers' mirror-system areas did not show any activity.

Daniel Glaser, of the Institute of Cognitive Neuroscience at UCL, said that although dancers frequently make reference to "body memory," movement is really learned in the brain. "But what wasn't clear," Glaser said, "was that that bit of the brain was also activated when you see movement, and that is the critical insight here. You use your ability to move, your movement-control part of the brain, to help you see better."

An expert's physical skill, therefore, helps him understand what he is seeing.

The study's findings suggest that dancers and athletes might benefit from training mentally while recovering from injury. It might also help in the rehabilitation of stroke victims whose motor skills have been damaged.