paper 1998
Reaction Time

The interval of time between application of a stimulus and detection of a response.

Your hand accidentally touches the hot plate of an oven and is withdrawn immediately. A young child runs out in front of your car and you hammer on the brakes. A lottery ball falls into its position upside down and you have to shout out the correct number as fast as you can to a colleague who is checking off the numbers for your syndicate. All three examples of reaction time are the time it takes to make a movement in response to a sensory stimulus. However, even if we try to respond as fast as possible in each situation, the reaction time is quite different.

In this context, time is measured in milliseconds (ms) — thousandths of a second. It may take only 100 ms to withdraw our hand from the stove, 200 ms to stamp on the brakes, and 500 ms to read out the number on the ball. The difference occurs because of the different amount of time it takes for the central nervous system (CNS) to process the sensory signals and to choose the appropriate course of action.

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