Cowboys in the lab
22 Apr 2010 by Evoluted New Media
It was no secret in the Wild West that he who draws their pistol last draws quickest - but why is this, and what use is it to biologists today?
It was no secret in the Wild West that he who draws their pistol last draws quickest - but why is this, and what use is it to biologists today?
PLAYING cowboys is something boys never grow out of – no matter how old. Nobel Prize winning physicist Niels Bohr could not resist – in between fathoming the constitution of the atomic nuclei and developing the concept of complementarity, he is reported to have found the time to explain why in films, cowboys who drew their weapon second always won the shoot out.
Using cap guns, he and colleagues enacted Wild West duals – Bohr, playing the 'goodie', drew his weapon second, but won every time. He concluded that this was because humans respond quicker in reaction to something than when they are initiating an action.
Nearly a century on from Bohr’s work, scientists funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and the Wellcome Trust has carried out “laboratory gunfights”, but rather than drawing toy guns, participants pressed a panel of buttons instead.
Dr Andrew Welchman, a BBSRC David Phillips Fellow at the University of Birmingham who led the research, explains: “In our everyday lives, some of the movements we make come about because we decide to make them, while others are forced on us by reacting to events. Bohr’s suggestion reflects this everyday intuition. This idea that the response to what you see in the environment might be quicker to execute is the seed for this piece of research. We wanted to know if there was evidence for these reactive movements being swifter than the equivalent proactive ones.”
Dr Welchman and his team developed a behavioural paradigm to test movement dynamics for intentional versus reactionary movements and look for evidence of a reactive advantage in movement execution. Fifty four men and women aged between 18 and 39 took part. The competition consisted of pairs of participants sitting opposite each other and pressing three buttons in sequence as quickly as possible. There was no ‘go’ signal to start the competition, so all they had to go by was either their own intention to move or a reaction to their opponent. Dr Welchman found that when reacting, participants were about 21 milliseconds (ms) or 10% faster than when initiating the button pressing, although they did not respond as accurately in the test.
Another avenue Dr Welchman wanted to explore was whether the social context in which the competitor was competing might have an impact on reaction times. Research has shown a difference in performance when people believe they are competing against a computer rather than another person. So, as well as competing against each other, participants also played against a computer, sometimes being told it was a ‘computer opponent’ and other times being told they were playing another human interfaced via the computer. Interestingly the team found the reactive advantage was consistent throughout, regardless of the social set-up.
“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. 21ms may seem like a tiny difference, and it probably wouldn’t save you in a Wild West dual because your brain takes around 200ms to respond to what your opponent is doing, but it could mean the difference between life and death when you are trying to avoid an oncoming bus!” explains Dr Welchman.
While this research did not look directly at what is happening in the brain to cause the faster reaction movements, Dr Welchman speculates that it is all to do with the route taken by the movement message when it is sent to the brain.
“When we are reacting to things around us, the information comes in through our eyes, gets sent to the back of our brains and up towards the motor cortex which controls our movements. In contrast, when we actively initiate a movement, signals from the decision areas at the front of the brain get sent back towards the motor areas of the brain. The key idea is that the brakes keeping our bodies in place effectively get taken off faster when we make a reactive movement. This quick release mechanism could be responsible for us being 20ms swifter when we make a response to our opponent.”
But far from being a quirky piece of research about reaction times, Dr Welchman
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| “I suspect the reason that Bohr won his mock duals had more to do with him being a crack shot, in addition to being a brilliant physicist,” |
There is already quite a lot of evidence that different brain areas are associated with different types of action. For instance, Parkinson’s disease seems to affect intentional movement more than reactive movements. Anecdotal reports suggest that people with Parkinson’s disease find intentional movements far more difficult than reactive ones – if you ask someone with Parkinson’s to pick up a ball from a table they can find it far more difficult than they would to catch the same ball if it were thrown at them. This might be evidence that particular areas of the brain affected by Parkinson’s contribute more to intentional actions than reactive ones. If this turns out to be the case, then it might also be possible to develop some strategies to ease movement in such patients.
Dr Welchman currently holds two BBSRC grants, one looking at movement control and timing and the other looking how the brain combines different sensory signals to estimate properties of the world around us. “As humans, we adapt our behaviour based on our brain responding to the statistical regularities of the environment to maximise its use of available information. One area we are investigating in detail is the ability to synchronise actions with environmental events – ensuring that we are in the right place at the right time. We are currently looking at ways to use the new knowledge generated by the project to help athletes and performers as well as our ageing population,” he explains.
Using a lab-based task of finger tapping in time with a metronome, the team in Birmingham have found that movement timing is improved if there are two cues available – such as a flash of light alongside the metronome. The team hopes that such findings could be translated in to a simple hand held device which could help older people pace their walking by giving them a touch or light-based cue, rather than relying on a loud noise, which in the outside environment can get lost.
“Evidence suggests that older people often lose their confidence after a fall, so we are looking at ways to develop confident, steady walking using simple electronics in people’s homes, to help them remain independent for longer,” he says.
Replacing sound cues for timing not only has implications for movement in older people and rehabilitation of stroke patients; athletes and musicians could also benefit from this work. “Timing is crucial in events such as rowing. We are used to the idea of sound cues for timing, but there are a number of situations where sound can be unreliable. In a rowing boat for example there is an interface effect in sound due to reflection from water and so sound may not be the best thing to use. Using a flashing light alongside the cox’s instruction could help improve the boat’s synchronised rowing,” he explains.
Coming back to gunfights, interestingly, Dr Welchman’s research has not actually proved Bohr’s Wild West theory to be correct. While he has confirmed that reactive movements are swifter than intentional ones – shown by the 21ms difference in carrying out a button-pressing challenge in the lab – the overall time from event to completion of the reaction would not be quicker for the good-guy due to the 200ms it takes our brains to process that something has happened and needs to be responded to.
“I suspect the reason that Bohr won his mock duals had more to do with him being a crack shot, in addition to being a brilliant physicist,” he concludes.
