Extraneous variables

• What are extraneous variables?

  External factors influencing the dependent variable
• Why do researchers aim to control extraneous variables?

  To ensure accurate measurement of the dependent variable
• What is a confounding variable?

  A type of extraneous variable that varies with the IV
• How do confounding variables differ from extraneous variables?

  Confounding variables vary systematically with the IV
• What are the differences between extraneous and confounding variables?

  Extraneous Variables:

  • Nuisance variables
  • Do not vary systematically with IV
  • Easy to control

  
  

  Confounding Variables:

  • Affect the DV
  • Vary systematically with IV
  • Difficult to control
• What are participant variables?

  Personal variables concerning study participants
• How can participant variables confound the dependent variable?

  If not controlled, they can skew results
• What are situational variables?

  Aspects of the research situation affecting results
• How can situational variables confound the dependent variable?

  If uncontrolled, they can alter participant performance
• What are demand characteristics?

  Features that influence participant behavior
• How do demand characteristics affect participants?

  Participants may change behavior based on cues
• What are investigator effects?

  Influences from the investigator on participants
• How can investigator effects manifest in a study?

  Through subtle cues like facial expressions
• What are order effects?

  Effects from the order of conditions in experiments
• What are the two types of order effects?

  Practice effects and fatigue effects
• How can researchers control for participant variables?

  • Random allocation to conditions
  • Screening participants before the study
  • Using the same participants across conditions
• How can researchers control for situational variables?

  • Use a lab setting
  • Ensure constancy for all participants
• How can researchers control for demand characteristics?

  • Deceive participants about the study's aim
  • Use distraction tactics in questionnaires
  • Employ a field setting for the study
• How can researchers control for investigator effects?

  • Use a third party for testing
  • Ensure the researcher is unaware of conditions
• How can researchers control for order effects?

  • Use different participants for each condition
  • Implement time breaks between conditions
  • Counterbalance the order of conditions