Reaction time

• Measuring a person's reaction time

  1. Person 1 sits on a stool with good upright posture

  2. Person 1 places the forearm of their dominant arm across the table with hand overhanging the edge

  3. Person 2 holds a ruler vertically with the 0 cm mark between Person 1's thumb and first finger

  4. Person 2 tells Person 1 to prepare to catch the ruler

  5. Person 2 drops the ruler at a random time

  6. Person 1 catches the ruler with thumb and first finger as quickly as possible

  7. Person 2 records the measurement on the ruler level with Person 1's thumb

  8. Repeat the test several times and calculate the mean
• Reaction time


  Time taken for Person 1 to catch the falling ruler
• Independent variable


  The person having the reaction time tested
• Dependent variable


  The reaction time
• Control variables


  • Constant working distance between thumb and first finger
  • Measure the ruler at the top of the thumb
  • Keep conditions in the room the same (lighting, background noise)
• Other independent variables that could be investigated:
• Investigating effect of practice

  One person catches the ruler many times, see if reaction time changes
• Investigating effect of hand used

  Test with dominant hand, then non-dominant hand of same person
• Investigating effect of caffeine

  1. Test subject drinks measured amount of cola 30 mins before, compare to normal reaction time

  2. Also test with caffeine-free cola
• Need to check test subjects have no medical issues that could be affected by caffeine
• Tests should be carried out in a lab where hazardous chemicals are not normally used