Required Practical - Human Reaction Times
Biology: AQA GCSE Higher, topic 5.2.6
Investigating Human Reaction Times
It is possible to investigate the effects of various factors on human reaction times through a practical experiment.
Testing reaction time
- If the reaction time is reduced this means it takes less time to react.
- So, a reduction in the reaction time does NOT mean that someone is reacting more slowly, it means they are reacting more quickly.
Factors
- Caffeine and exercise are factors that could affect human reaction time
- Their effect can be tested by dropping and catching a ruler.
Procedure
The steps in the practical procedure are:
- Hold a ruler vertically from one end. The test subject should have their thumb and finger either side of the ruler at the 0cm mark.
- Drop the ruler. The subject should try to catch it between their thumb and forefinger as fast as possible.
- Note down the distance from the 0cm mark that the ruler travels before the subject catches it.
- Use a table to convert this distance into a reaction time.
- Repeat the experiment on a subject who has just had a coffee, or who has just done exercise.
- Compare reaction times.
Variables
- The independent variable is whether or not the subject has had caffeine or exercised.
- The dependent variable is the subject’s reaction time.
Test yourself on Required Practical - Human Reaction Times
In a ruler-drop test investigating how caffeine affects the body, what is the dependent variable?
In the ruler-drop test, a subject catches the ruler at a shorter distance after drinking coffee than before. Based on the known effect of caffeine, what does this result confirm?
In the ruler-drop experiment, why is the test repeated on a subject after they have had coffee or exercised?
The source states that caffeine reduces reaction time. What does the source tell us about how exercise affects reaction time?