Science -- Your Future, Scotland's Future
SCI-FUN Roadshow Exhibits -- Reaction Timer
SCI-FUN Roadshow Exhibits -- Reaction Timer
In this exhibit you learn about how quickly you are able to respond to things.

Our reaction time is the time it takes for us to respond to something happening. In this time, our senses notice something and send a signal back to the brain, the brain then comes up with an appropriate response and sends a signal down to our muscles to carry out an action.

The fastest possible conscious human reactions are around 0.15 s, but most are around 0.2 s. Unconscious, or reflex, actions are much faster, around 0.08 s because the signal doesn't have to go via the brain. Reflex actions occur in response to danger, for example moving your hand away from something hot or blinking when something moves quickly towards your eyes.

In sport, reaction time is very important. Players must be able to respond very quickly to the actions of another player, or the movement of a ball. Sprinters need to be able to react fast to the starting pistol, as a difference of 0.05 s in reaction time can be the difference between first and second place.

False starts are common in sprints because the runners are keen to respond quickly and often anticipate the gun before it goes off. The International Association of Athletics Federations takes reaction time into consideration when judging false starts. If a sprinter moves within 0.1s of the pistol, this is considered to be a false start, as it is impossible for them to have reacted that fast.

Reaction time can be improved with training, by doing activities that require a fast reaction time. People who play sport or play computer games often have fast reaction times because they practise responding quickly to things. Having fast reaction times is important in driving, as drivers often have to respond quickly to avoid accidents.

Our reaction times change depending on circumstances. Tiredness greatly reduces our reaction times, as does drinking alcohol. That is why driving whilst tired is not advised, and drink-driving is illegal. Old age also reduces our reaction times, and driving ability lessens with age.

1 Our reaction time is the time it takes for us to ________ to something happening.
2 What do reflex actions respond to?
3 Is moving 0.09 s after the gun in a sprint race a false start?
4 What activities might improve your reaction time?
5 Why shouldn't you drink and drive?
6 Can you think of any simple games that you could use to improve your reaction times?

1 You can use a regular ruler as a reaction timer, however you will only be able to read off reaction times in terms of the number of cm that fell, and not in seconds. Test out your reaction time at different times of the day: when you get up, lunchtime, early evening and bedtime. Try it out before and after exercise to see how it changes.
2 Choose a particular activity to train yourself and improve your reaction time, and do that activity on a regular basis (this can't be something you'd be doing anyway). Test your reaction time using a ruler, and see how it changes with training. Do you notice a difference after a week, a month? Does your time improve immediately after training?