Reaction Time

• Caffeine and exercise are factors that could affect human reaction time
• Their effect can be tested by dropping and catching a ruler.

The steps in the practical procedure are:

1. Hold a ruler vertically from one end. The test subject should have their thumb and finger either side of the ruler at the 50cm mark.
2. Drop the ruler. The subject should try to catch it between their thumb and forefinger as fast as possible.
3. Note down the distance from the 50cm mark that the ruler travels before the subject catches it.
4. Use a table to convert this distance into a reaction time.
5. Repeat the experiment on a subject who has just had a coffee, or who has just done exercise.
6. Compare reaction times.

• The independent variable is whether or not the subject has had caffeine or exercised.
• The dependent variable is the subject’s reaction time.

• Quadrats are square frames that can be used to estimate population sizes.

• Transects can be used to investigate the effect of a factor on the distribution of a species.
• A transect line is a piece of tape that is stretched across the habitat of interest.
• Quadrats are placed at regular intervals along the transect line.