Required Practical: Reaction Time (AQA GCSE Biology): Revision Note

RP7: Reaction time

• Reaction time is the time taken to respond to a stimulus

• Reaction time can be affected by factors such as:

  • age

  • stress

  • caffeine intake

Aim

• Plan and carry out an investigation into the effect of a factor on human reaction time

Method

1. Each volunteer needs to sit in a chair with a good upright posture 

2. Ensure that the volunteer places their forearm on the table so that it extends over the edge 

3. Ask the volunteer to place their thumb and fingers finger on either side of the lower edge of a vertically placed meter ruler with 0 cm at the bottom and 100 cm at the top

4. Tell the volunteer that the ruler will be dropped without warning; the volunteer needs to catch the ruler with their thumb and forefinger as soon as they sense it dropping

5. Drop the ruler. When your volunteer catches it, record the number on the ruler displayed just over the thumb

   • The lower the number, the faster the reaction time

6. Conduct five trials with the same volunteer

7. Repeat the experiment with a changed independent variable, e.g.

   • a different volunteer

   • after a caffeinated drink

   • with loud music playing

8. Use a conversion table to convert the measurements into reaction times

Use image

• 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 oriented 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, o

  • if background noise is being investigated then the room should be silent for the first set of repeats

Interpreting information about the nervous system

• It is necessary to be able to extract and interpret data from graphs, charts and tables about the functioning of the nervous system

• This includes calculations such as mean reaction times or evaluating whether a mean is reliable if any anomalous results were included