Investigation: Reaction time
Ruler drop test
A simple method to measure reaction time is to use the ruler drop test.
Aim
The aim of this experiment is:
- to measure human reaction time;
- compare human reaction time with and without background noise.
Apparatus
- 50 cm rule;
- radio or Smart speaker.
Carrying out the investigation
- Work with a partner. Ensure that the room is totally quiet.
- 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 they must catch it.
- The number level with the top of person A's thumb is recorded in a suitable table. Repeat this five times.
- Now play loud music through a speaker and ask some friends to carry out a loud conversation beside Person A.
- Repeat the investigation again and record the number level with the top of person A's thumb in the table.
- You can use the conversion table to help convert your ruler measurements into reaction time or just record the catch distance in centimetres.
The process of catching a ruler to test reaction time
| Attempt | Distance on ruler (cm) | Distance on ruler (cm) |
| number | Without noise | With background noise |
| 1 | 18 | 25 |
| 2 | 15 | 38 |
| 3 | 22 | 36 |
| 4 | 24 | 31 |
| 5 | 13 | 38 |
| Average | 18.4 | 33.6 |
| Attempt | 1 |
|---|---|
| Distance on ruler (cm) | 18 |
| Distance on ruler (cm) | 25 |
| Attempt | 2 |
|---|---|
| Distance on ruler (cm) | 15 |
| Distance on ruler (cm) | 38 |
| Attempt | 3 |
|---|---|
| Distance on ruler (cm) | 22 |
| Distance on ruler (cm) | 36 |
| Attempt | 4 |
|---|---|
| Distance on ruler (cm) | 24 |
| Distance on ruler (cm) | 31 |
| Attempt | 5 |
|---|---|
| Distance on ruler (cm) | 13 |
| Distance on ruler (cm) | 38 |
| Attempt | Average |
|---|---|
| Distance on ruler (cm) | 18.4 |
| Distance on ruler (cm) | 33.6 |
Conversion table
| Catch distance (cm) | Reaction time (ms) |
| 1 | 45 |
| 5 | 101 |
| 10 | 143 |
| 15 | 175 |
| 20 | 202 |
| 25 | 226 |
| 30 | 247 |
| 35 | 267 |
| 40 | 286 |
| Catch distance (cm) | 1 |
|---|---|
| Reaction time (ms) | 45 |
| Catch distance (cm) | 5 |
|---|---|
| Reaction time (ms) | 101 |
| Catch distance (cm) | 10 |
|---|---|
| Reaction time (ms) | 143 |
| Catch distance (cm) | 15 |
|---|---|
| Reaction time (ms) | 175 |
| Catch distance (cm) | 20 |
|---|---|
| Reaction time (ms) | 202 |
| Catch distance (cm) | 25 |
|---|---|
| Reaction time (ms) | 226 |
| Catch distance (cm) | 30 |
|---|---|
| Reaction time (ms) | 247 |
| Catch distance (cm) | 35 |
|---|---|
| Reaction time (ms) | 267 |
| Catch distance (cm) | 40 |
|---|---|
| Reaction time (ms) | 286 |
One millisecond is one thousandth of a second. It can also be written as 10−3 s.
Conclusion
There is a clear difference between length of ruler that passed through the fingers before it was caught, with and without background noise.
For example, the average distance travelled by the ruler before it was caught with background noise was 33.6 cm compared to 18.4 cm without noise.
This suggests that background noise increases the human reaction time of the person in this experiment.
