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  • I guess we are all familiar with Hollywood portrayals of gun fights in the Wild West?

  • What we see there is that it is normally the good guy who is responding to the bad guy

  • pulling their gun and shooting at them who wins the dual. And this idea that the response

  • to what you see in the environment might be quicker to execute is really what was the

  • seed that lay at the heart of this piece of research. So we wanted to go beyond that just

  • quirky idea of a difference between reactive movements being faster than decisions to move

  • made by themselves and see whether this might actually map on to what different parts of

  • the brain might be doing to control those different types of actions.

  • So to try and test this idea about the difference between movements that we choose to make and

  • movements that we make in response to something else that is happening, we designed an experiment

  • where we got 2 people in the lab performing a virtual gun fight, a rather simple one that

  • involved pressing 3 buttons. We have 2 people facing each other and they compete to make

  • this movement as quickly as possible. On some trials 1 of the individuals would start off

  • the movement sequence and their opponent would then react to them making a movement and then

  • on other trials that same individual would not be making the decision to move but would

  • rather be reacting to it.

  • So what we found was that when people reacted to their opponent they made the movement about

  • 20 milliseconds faster than if they had been making that movement as an intention movement

  • - so reaction was quicker by about 20 milliseconds. So that really suggests that there might be

  • an advantage in responding to what is happening in the environment in that it makes you a

  • little bit quicker. Although you are 20 milliseconds faster in making the movement there is obviously

  • a delay between seeing what the other person is doing and then responding to that and that

  • is in the region of 200 milliseconds. So the system has probably evolved as a useful means

  • of getting out of the way of things. So if there is a bus coming towards us and want

  • to get out of the way as fast as possible and this ability to make quick, fast movements

  • is probably what we are tapping into with this experiment.

  • So having seen this difference in movement times the obvious question is "what is happening

  • in the brain that is responsible for this?" Our experiment hasn't tested that directly

  • but 1 speculative idea is that there are different routes to the production of these different

  • types of movement. One idea is that when we are reacting to things around us in the world

  • then information comes in through the eyes, gets sent to the back of the brain and then

  • from the back of the brain up towards the areas that control our movements. In contrast

  • to that when we make a decision to move the decision areas at the front of the brain get

  • sent back towards the motor areas of the brain. And the key idea is that effectively the brakes

  • get taken off faster when we make a reactive movements, so we can get moving faster than

  • when we make an intention movements, and that would be responsible for us being 20 milliseconds

  • quicker when we make a response to our opponent.

I guess we are all familiar with Hollywood portrayals of gun fights in the Wild West?

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