extraneous variables

• participant variables - how do people differ

  situational variable - how can a situation differ

  participant effect - how can a person affect the study
• participant variables - people differ in age, gender, mood and experience. research needs to consider this for good control
• situational variable - time of day, temp, noise can all differ -> practice effects can occur in repeated measures and fatigue
• investigation effects - cues from the investigator that encourage certain behaviour to the ppt in how to act -> use video instructions instead
• ways to reduce extraneous variables

  double blind - ppt and researcher doesn't know what condition they are in
• ways to reduce extraneous variables

  single blind - the ppt only doesn't know what condition they're in - reduces DC
• ways to reduce extraneous variables

  standardised procedures- every ppt does exactly the same thing in the same order
• what is a conformity variable?

  when an extraneous variable has not been properly controlled it affects the DV