Reacting to an opponent drawing their pistol faster than deciding to draw first, scientists say, confirming what often happens during duals in old Western films.
Credit: wikimedia
SYDNEY: Just like in the old Western gunfights, people move faster when reacting to a trigger than if they initiate movement, which shows movement has different brain pathways, scientists said.
Published today in the journal Proceedings of the Royal Society B, the study suggests that reactive movements and intentional movements use different brain pathways.
"In our daily lives, we constantly mix intentional movements, for example putting a cup on a table, with reactive movements, for example catching the cup after we knock it off the table by mistake," said lead researcher Andrew Welchman, a psychologist from the University of Birmingham, UK.
Parkinson's points to different brain pathways
"Your movement time - that is, how long it takes to move - is swifter when you react," he added.
Scientists working with Parkinson's disease patients have long thought that different brain pathways must be involved in different movement types.
People with Parkinson's disease often struggle more with intentional movement than reactive movement - while they can't pick a ball up from a table, they may be able to catch it.
Tip-off from Western films
This hints that the brain area damaged by Parkinson's disease controls only specific types of movement.
Nobel laureate Niels Bohr also pondered intentional versus reactive movement. Observing gunfights in wild western movies, he wondered why the cowboy who drew his gun first always got shot.
Bohr tested his theory - that reaction is faster than action - by duelling with colleague George Gamow using toy pistols.
Racing to push buttons
In a more rigourous experiment, Welchman and coworkers pitched 10 volunteers against each other in a series of 'lab-duels'.
Sitting opposite each other, each with their own set of buttons, pairs of volunteers duelled with each other, trying to complete a series of button presses faster than their opponent.
There was no start signal - like in a gunfight, volunteers either chose to start the duel by reaching for the first button, or raced their opponent when they saw them start.
On average, volunteers completed the button-press task 21 milliseconds, or 9% faster when reacting to an opponent than when initiating the duel. This advantage is unlikely to help you win a gunfight, however - although faster, reactive movements were less accurate.
It also takes around 200 milliseconds to start reacting to someone - during which time you are likely to get shot.
Despite limited use in a gunfight, Welchman speculates that this reactive advantage may have evolutionary roots.
Fast reaction is survival strategy
"As a general strategy for survival, having this system in our brains that gives us quick-and-dirty responses to the environment seems pretty useful.
"Twenty-one milliseconds may seem like a tiny difference, but it could mean the difference between life and death when you are trying to avoid an oncoming bus!" he said.
His experimental set-up could also be medically useful.
"Our study in normal participants might tap into the brain systems that are sensitive to Parkinson's - as such using our test could provide an early warning for people who might go on to develop a movement disorder," he speculated.
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