Reaction time is the time between a stimulus (something you see or hear) and your response. For most alert people it is around 0.2 s, and typical values lie between about 0.2 s and 0.9 s.
Two common methods:
- Ruler drop test: a partner holds a ruler vertically with the zero mark level with your open thumb and finger. They let go without warning and you catch it as fast as you can. The distance the ruler fell is read from the scale. The ruler falls under gravity, so a longer distance means a longer reaction time. A table or a calculation turns the distance into a time.
- Computer test: the person clicks the mouse or presses a key when the screen changes colour. The computer measures the time between the change and the response.
A single result can be unreliable, so the test is repeated several times and the mean is calculated. This makes the result more reliable. The same person, the same hand and the same starting position should be used each time so that only one variable changes.
