Topic 5 - Required Practical: Reaction Time

• • Aim: to plan and carry out an investigation into the effect of a factor on human reaction time
  • You will:
  • Choose a factor that you wish to investigate that will have an effect on reaction time
  • Carry out a number of experiments to measure reaction time
• • Reaction time is the time taken to respond to a stimulus; reactions are usually very quick responses typically taking less than a second to occur
  • Reaction time can be affected by factors such as age, stress or use of drugs (such as caffeine)
• • You could investigate the effect of background noise or consumption of caffeine on how quickly a person catches a ruler
  • Reaction time can be measured in this way using the principle that the further down the length a ruler is caught, the slower an individual's reaction time
• • The experiment can be repeated several times to calculate a mean average distance caught and this can be equated to a reaction time
  • The process is then repeated after a condition is changed (the person drinks a can of caffeinated drink or has to repeat the experiment when loud background music is playing)
  • Remember to only change one factor (independent variable) in your investigation
• • There are many control variables that should be considered in this experiment such as:
  • The person catching the ruler using their dominant hand each time
  • Dropping the same ruler from the same height each time, with the ruler orientated in the same direction (0 cm facing down)
  • If the effect of caffeine is being investigated then none should have been consumed before the start of the experiment, or the room is silent for the first run if background noise is being altered
• • It is possible to carry out a reaction time investigation using a computer; this is obviously more precise as it removes human error from measurements
  • Reaction time can also be recorded in milliseconds which is more accurate than seconds
• 1. Work with a partner to do the test. Decide who is person 1 and person 2, and what factor you are going to change
  2. Person A holds out their hand with a gap between their thumb and first finger.
  3. Person B holds the ruler with the zero at the top of person A's thumb
  4. Person B drops the ruler without telling Person A and they must catch it
  5. Record the number on the ruler that is level with A's thumb
  6. Repeat 10x
  7. Swap places and repeat 10x for person B
  8. Change one factor - drink a caffeinated drink - Record all results
  9. Use a conversion table to convert ruler measurements into reaction times
• Interpreting Information about the Nervous System

  • In the exam, you must be able to extract and interpret data from graphs, charts and tables about the functioning of the nervous system
• • Three students played a computer game which measured their reaction time to click when they saw a blue light flash on the screen
  • Their results were recorded
  • You could be asked to: calculate the mean reaction time for each student, or be given the means and asked to identify if any had been calculated incorrectly/anomalous results were included
  • Anomaly - student C on their third attempt – 573 ms - shouldn't be used to calculate a mean
  • The lowest reaction time = fastest reaction time – Here, student A = fastest reaction time and student C = slowest