Reaction time (required practical): Homeostasis and response: Biology: GCSE (9:1)

• Reaction time


  The amount of time taken to respond to a specific stimulus
• How to measure reaction time

  Catch a dropped ruler from a specific height, record the length caught in metres and then convert this into reaction time in seconds

  
• Conversion table


  A table that uses a formula to convert the distance of a caught ruler into reaction time in seconds
• Metre ruler


  The object that is held vertically above a participant's hand before it is dropped and caught

  
• Dependent variable


  The variable that is measured which is the reaction time in seconds for this experiment
• Independent variable


  The variable that is changed which could be the person tested, the presence of blindfolds or caffeine consumption

  
• Control variables

  The variables that are kept the same such as starting height, the person dropping the ruler, lighting and background noise
• Effect of practice

  The person catching the ruler may find it easier each time due to more experience which can be difficult to control
• Caffeinated and decaffeinated drinks

  Conducting a blind trial using unlabelled drinks that may or may not be caffeinated can account for the placebo effect

  
• Placebo effect

  A participant may have certain bias expectations during an investigation that may cause them to perform differently

  
• Blind trial


  A trial where participants are unaware of whether or not they have received a genuine treatment or a placebo
• Placebo

  A fake treatment or condition used in an investigation to determine the validity of an experiment

  
• Posture


  It is important for participants to keep their body and arm in the same position for each test

  
• Dominant arm


  The arm used for most activities, the same arm should be used for each test unless it is the independent variable
• Mean average

  The total sum of the data values divided by the number of times the data was recorded