The intersection of physics and gunslingers

Draw! [Link]

In Western films, the gunslinger that draws first always gets shot. This seems like a standard Hollywood trope but it diverted the attention of no less a scientist that Niels Bohr, one of history's greatest physicists. Taking time off from solving the structure of the atom, Bohr suggested that it takes more time to initiate a movement than to react to the same movement. Perversely, the second gunslinger wins because they're responding to their opponent's draw.

Now, Andrew Welchman from the University of Birmingham has found that there's something to Bohr's explanation. People do indeed have a "reactive advantage", where they execute a movement about 10% more quickly if they're reacting to an opponent. Of course, ethics committees might frown on scientists duelling with the pistols in the name of discovery, even if the people in question were graduate students. So Welchman designed a laboratory gunfight, played out using buttons rather than guns.

Two opponents faced each other and had to press a series of three buttons as quickly as possible. To begin with, they held a central "home key" with their trigger fingers and they had to wait for a short spell before before starting the round. The point where they were allowed to begin varied from trial to trial and the players weren't told how long it would be. There was no starting pistol or countdown. Either player could start the race but if they went too soon, an alarm would sound to signal a false-start.

These button-mashing duels revealed that, on average, the players completed their sequence 21 milliseconds faster if they reacted than if they initiated. That's an improvement of around 9%, and most of this advantage came at the very beginning, when they pressed the first button. It's an interesting result and like all good scientists, Welchman systematically considered and ruled out several possible explanations for it.