Practical activity
Plan and carry out an investigation into the effect of a factor on human reaction times
You can carry out a number of investigations to determine the effect of a specific factor on human reaction times.
A suitable investigation could be the effect of caffeine or the amount of background noise in the room. A simple method to measure the effect is to use the ruler drop test.
Ruler drop test
- Work with a partner.
- Person A holds out their hand with a gap between their thumb and first finger.
- Person B holds the ruler with the zero at the top of person A's thumb
- Person B drops the ruler without telling Person A and Person A must catch it.
- The number level with the top of person A's thumb is recorded in a suitable table. Repeat this five times without background noise and five times with background noise.
- Swap places, and record another ten attempts.
- You can use the conversion table to help convert your ruler measurements into reaction time or just record the catch distance in cm.
Distance | Time |
1 cm | 50 ms |
5 cm | 90 ms |
10 cm | 140 ms |
15 cm | 170 ms |
20 cm | 200 ms |
25 cm | 230 ms |
30 cm | 250 ms |
Distance | 1 cm |
---|---|
Time | 50 ms |
Distance | 5 cm |
---|---|
Time | 90 ms |
Distance | 10 cm |
---|---|
Time | 140 ms |
Distance | 15 cm |
---|---|
Time | 170 ms |
Distance | 20 cm |
---|---|
Time | 200 ms |
Distance | 25 cm |
---|---|
Time | 230 ms |
Distance | 30 cm |
---|---|
Time | 250 ms |
Example results:
Attempt | Distance on ruler with noise | Distance on ruler without noise |
1 | 25 cm | 18 cm |
2 | 38 cm | 15 cm |
3 | 36 cm | 22 cm |
4 | 31 cm | 24 cm |
5 | 38 cm | 13 cm |
Attempt | 1 |
---|---|
Distance on ruler with noise | 25 cm |
Distance on ruler without noise | 18 cm |
Attempt | 2 |
---|---|
Distance on ruler with noise | 38 cm |
Distance on ruler without noise | 15 cm |
Attempt | 3 |
---|---|
Distance on ruler with noise | 36 cm |
Distance on ruler without noise | 22 cm |
Attempt | 4 |
---|---|
Distance on ruler with noise | 31 cm |
Distance on ruler without noise | 24 cm |
Attempt | 5 |
---|---|
Distance on ruler with noise | 38 cm |
Distance on ruler without noise | 13 cm |
Question
What effect does noise have on the speed of reaction, measured in centimetres? [2 marks]
There is a clear difference between length of ruler that passed through the fingers before they managed to catch it, with and without noise. [1 mark]
For example, the first set of data, with noise 鈥 25 cm compared to without noise 鈥 18 cm. It suggests that noise reduces the response times of the person in this experiment. [1 mark]
Tip: include at least two or three sets of data from the results.