Experimental designs

• Independent groups design 


  -two different groups of PP complete the two different experimental conditions.

  +Demand characteristics: decreased as only experience one of the two conditions.

  +Order effects: decreased as PP only do one condition

  -Individual differences: between the two groups of PP.
• Repeated measures 


  -the same PP take part in all conditions.

  +no individual differences: same PP are used in both conditions.

  -demand characteristics increase: could figure out the aim as they experience both conditions.

  -order effects: the order in which the PP's complete the conditions can affect the PP performance.
• Matched-pairs design 


  PP take part in only one experimental condition. They are recruited specifically to be similar in relevant characteristics to PP in the other condition. Identical pairs are best for this design.

  +demand characteristics are decreased: only do one part of the experiment so can't figure out the aim.

  +no order effects: only doing one condition.

  -time consuming: have to find matched pairs.

  -if one person wants to withdraw their details then the researchers loses two peoples data.