Extraneous variables

• Situational extraneous variables

  Aspects of the environment might affect the participants behavior
• ​Participant extraneous variables

  Characteristic of a participants that could affect the DV when it is not intended to
• Demand characteristics

  When participants detect cues from the environment which makes them guess the aim of the study and they change their behaviour as a result.
• Investigator effects 

  where a researcher (consciously or unconsciously) acts in a way to support their prediction and therefore affects the DV.
• Order effects 

  Participants responses in the are affected by the order of conditions to which they were exposed
• Participant reactivity

  When participants alter their behaviour because they know they are part of a study and this can threaten the internal validity of the results.
• Extraneous variables

  Variables other than the IV which could affect the DV and should be controlled.
• Confounding variables 

  Variables which have affected the DV and have threatened the validity of the results.