Coordination and control - The nervous system - AQA Required practical activity 7
The nervous system enables humans to react to their surroundings and to coordinate their behaviour. It comprises millions of neurones and uses electrical impulses to communicate very quickly.
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 they must catch it.
The number level with the top of person A's thumb is recorded in a suitable table. Repeat this ten times.
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
Attempt
Distance on ruler
Distance on ruler
With noise
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
Distance on ruler
With noise
Distance on ruler
Without noise
Attempt
1
Distance on ruler
25 cm
Distance on ruler
18 cm
Attempt
2
Distance on ruler
38 cm
Distance on ruler
15 cm
Attempt
3
Distance on ruler
36 cm
Distance on ruler
22 cm
Attempt
4
Distance on ruler
31 cm
Distance on ruler
24 cm
Attempt
5
Distance on ruler
38 cm
Distance on ruler
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 – 30 cm compared to without noise – 20 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.