Not only are the ring and pinky fingers physically tethered together by a shared tendon, as anatomists long have known; measurements of neuromuscular activation patterns have shown that all fingers, including the ones with the greatest structural autonomy, the thumb and index finger, are keenly responsive to every flex and twitch of their neighboring digits.

“Even when you think you’re moving just one finger,” said Marc H. Schieber, a professor of neurology and neurobiology at the University of Rochester Medical Center, “you’re really controlling your entire hand.”

The pianist playing Ravel or the typist clacking on Blogspot? “People tend to think, they’re hitting one key at a time, so they must be moving one finger at a time to hit that key,” Dr. Schieber said. “But really, all the fingers are in motion all the time.”

For every keystroke, there’s a movement of every finger. “Some of the movement is to strike the key,” Dr. Schieber said, “others to lift fingers back up and away from the key, others to hold them away.”

The brain also treats the hands as unified tools, often in ways of which we’re not consciously aware. Scientists have shown that our hands start assuming the necessary configuration as soon as the brain initiates an activity — if not a micromoment earlier. If we’re reaching for a water bottle, the hand takes on a generic open cupping shape, refining the curvature and angle of the gesture as the hand closes in on the bottle.

In groping for a pen, the thumb, index and middle fingers — the masters of fine-motor manipulations — form a preliminary pincer, while the ring finger and pinky (important for gripping bulkier objects, like bottles) tuck themselves politely under and out of the way. To appreciate the centrality of manual anticipation to the seamless performance of tasks, try blocking the pre-cupping maneuver as you reach for a glass, and see how clueless you and your hand will feel about how to proceed.