Extraneous and confounding Variables

• The researcher must make sure that there are no differences between the two groups apart from the independent variable (IV)
• What is an extraneous variable?


  A variable that does not vary systematically with the independent variable but may affect the dependent variable
• Why are extraneous variables problematic in research?


  They make it difficult to detect cause and effect
• What is a confounding variable?


  A variable that varies systematically with the independent variable
• How can confounding variables affect research outcomes?


  They can make the outcome meaningless by affecting the dependent variable
• What are demand characteristics in research studies?

  • Participants guessing the purpose of the research
  • Trying to please the researcher by giving 'right' results
  • Trying to annoy the researcher by giving 'wrong' results (screw you effect)
  • Acting unnaturally due to nervousness or fear of evaluation
  • Acting unnaturally due to social desirability bias
• What are investigator effects?


  Ways in which researchers unconsciously influence the results of research
• How can physical characteristics of investigators influence research results?


  They may affect participants' willingness to respond honestly
• What is a single blind design in research?


  A design where the participant is unaware of the research aims or conditions
• What is a double blind design in research?


  A design where both the participant and the researcher are unaware of the aims
• What is experimental realism?


  Making the task engaging so participants focus on it rather than being observed
• What are the ways to deal with extraneous variables in research?


  • Single blind design
  • Double blind design
  • Experimental realism
  • Standardisation
• What is the importance of standardised instructions in research?


  • They must be written in a verbatim format
  • They should include a check for participant understanding