extraneous variables

• double blind design


  • neither the ppt or researcher know who is in the different groups (experimental or control)
• single blind design


  • the ppts dont know which group they are in
• experimental realism 


  • the extent to which situations created impact are real to ppts
• participant variables

  • age, intelligence, motivation, experience and gender
• situational variables


  • order effects
  • time of day, temp noise
• standardisation


  • using exactly the same procedure for participants in a study
• confounding variables 


  • an unmeasured third variable that influences the relationship between the IV and DV