People are quicker when reacting than when initiating

Inspired by Hollywood cowboy films, researchers have delved into the science of gun fights.

Scientists discovered that people move faster when reacting to something than when they perform "planned actions".

In an experimental "duel", published in Proceedings of the Royal Society B, they studied the speed of these two types of movement.

As well as unpicking Wild West mythology, scientists hope the findings will shed light on movement disorders.

The team say the results could help diagnose conditions such as Parkinson's disease.

Gun-free duel

Pairs of participants were put in a button-pressing competition with each other. Each was secretly given instructions of how long to wait before pushing a row of buttons.

"There was no 'go' signal," said Dr Andrew Welchman from the University of Birmingham, who led the research.

"All they had to go by was either their own intention to move or a reaction to their opponent - just like in the gunslingers legend."

Those who reacted to their opponent were on average 21 milliseconds faster than those who initiated the movement.

"I wasn't expecting that we would find such a clear difference," said Dr Welchman.

"In our everyday lives we have this constant battle between things we decide to do and things we have to do to avoid a negative consequence."

"If you're making a cup of tea that would be an intentional decision. If we then knock the cup of tea off the table, the reactive comes into play as we try to catch the cup as fast as possible."

No consolation

The implications for gunslingers though are not straightforward, and the outcome of a Hollywood shoot-out, it seems, is based more on myth than science.

Dr Andrew Welchman explains the laboratory gunfight (Footage: BBSRC)

Dr Welchman explained that it took around 200 milliseconds to respond to what an opponent was doing, so, in a gunfight, the 21 millisecond reactionary advantage would be unlikely to save you.

"The person who draws second is going to die. They'll die happy that they are the faster person to move but it's not much consolation in this context," said Dr Welchman.

The scientists want to find out if there are two different brain processes underlying the two different types of action. They think there could be evidence for this in people with Parkinson's disease.

Dr Welchman says there is evidence that Parkinson's patients are more impaired in intentional movement than in reactive ones.

"If you're someone who's going to develop Parkinson's disease, this difference might get exaggerated," he said. "[So] you might be able to get an earlier idea that there could be problems with movement."