Experimental Designs

• Participants do both the experimental and control condition
• Same people in each condition
• Comparing each result 'like for like'

Advantages:

• Participant varaibles are controlled
  • They take part in both conditions so causality between the IV and DV can be established
• Fewer participants are needed
  • Each participant produces twice as much data so half as many participants are needed

Disadvantages:

• Demand characteristics
  • Aware thay are completing the same task but under slightly different conditions
• Order effects
  • Performance on the task completed the second time is likely to be improved through practice or worsened through boredom

• Different participants in each condition
• Comparing each group's performance

Advantages:

• Less chance of demand characteristics
  • Participants are unaware of the second condition so unlikely to guess the aim
• Less chance of order effects
  • Performance will not be improved or worsened

Disadvantages:

• Participant variables are not controlled
  • There are individual differences between participants .e.g. age, IQ and gender
  • Less certainity of causality between IV and DV

• Different participants in each condition
• Participants are 'matched' on key variables (E.g. IQ, age and gender) then split up so one is in each condition

Advantages:

• Less chance od demand characteristics and order effects
  • Participants only do one condition
  • Not improved through practice or worsened through boredom

Disadvantages:

• Extremely difficult to achieve
  • To match participants is a lengthy process and can become a research study in itself
  • Time consuming and expensive
  • Rarely used in psychological research