Reaction Time (Ruler Drop Test)
Aim:
To investigate how a factor (e.g. caffeine, distraction) affects human reaction time using the
ruler drop test.
Method:
1. One person sits with their arm resting on a table — hand hanging over the
edge with thumb and forefinger open.
2. Another person holds a ruler vertically so the zero mark is level with the top of their
thumb.
3. Without warning, the ruler is released.
4. The person being tested must catch the ruler as quickly as possible between their
thumb and forefinger.
5. Record the measurement at the top of the thumb (in cm) — this is the distance the
ruler fell before being caught.
6. Repeat several times and calculate a mean reaction distance.
7. Switch roles and repeat.
8. If testing a variable like caffeine or distractions (e.g. noise), repeat after the
condition is applied.
Variables:
INDEPENDENT VARIABLE: The condition being tested (e.g. caffeine, background noise,
talking).
DEPENDENT VARIABLE: The reaction time, measured by the distance the ruler drops.
CONTROL VARIABLES: Same ruler, same person dropping the ruler, same height start, same
hand used, same room conditions.
Common Mistakes:
1. Ruler not held at eye level – Makes it hard to line up and react properly.
2. Talking/laughing during test – Adds unintended distractions.
3. Inconsistent drop technique – Should always drop with no warning and no wobbling.
Risks:
1. Ruler hitting face/eyes – Unlikely, but still hold it sensibly.
2. Caffeine trial – Only use small, safe amounts (e.g. mild energy drink or tea).
3. Misuse of equipment – No throwing rulers at people, obviously.
Aim:
To investigate how a factor (e.g. caffeine, distraction) affects human reaction time using the
ruler drop test.
Method:
1. One person sits with their arm resting on a table — hand hanging over the
edge with thumb and forefinger open.
2. Another person holds a ruler vertically so the zero mark is level with the top of their
thumb.
3. Without warning, the ruler is released.
4. The person being tested must catch the ruler as quickly as possible between their
thumb and forefinger.
5. Record the measurement at the top of the thumb (in cm) — this is the distance the
ruler fell before being caught.
6. Repeat several times and calculate a mean reaction distance.
7. Switch roles and repeat.
8. If testing a variable like caffeine or distractions (e.g. noise), repeat after the
condition is applied.
Variables:
INDEPENDENT VARIABLE: The condition being tested (e.g. caffeine, background noise,
talking).
DEPENDENT VARIABLE: The reaction time, measured by the distance the ruler drops.
CONTROL VARIABLES: Same ruler, same person dropping the ruler, same height start, same
hand used, same room conditions.
Common Mistakes:
1. Ruler not held at eye level – Makes it hard to line up and react properly.
2. Talking/laughing during test – Adds unintended distractions.
3. Inconsistent drop technique – Should always drop with no warning and no wobbling.
Risks:
1. Ruler hitting face/eyes – Unlikely, but still hold it sensibly.
2. Caffeine trial – Only use small, safe amounts (e.g. mild energy drink or tea).
3. Misuse of equipment – No throwing rulers at people, obviously.
