Extraneous Variables

• Extraneous Variables


  Uncontrolled factors that can influence the outcome of an experiment and affect the results
• External Variables


  Examples: weather, time of day, season, noise level, day of the week, time of year
• Participant Variables/ individual Differences

  Differences between the participants which might affect their performanc.
• How do you deal with participant variable In research ?

  Use alternative experimental designs

  Repeated measures

  Random allocation
• Situational Variables


  The setting and the circumstances of the research which may affect the performance of the participants
• What can situational variables introduce?


  Order effects
• What are order effects?

  When the performance of participants in the second condition is impacted by their participation in the first. E.g getting better the second time
• How can you avoid situation variables in research? + summarise them

  Standardisation = ways in which the procedure/materials/instructions are all kept the same for all the participants. This ensures they all experience the same thing

  Counterbalancing = a way to balance out order effect
• Participant Reactivity

  The behaviour of the participants changes due to the awareness that they are being studied
• What does participant reactivity introduce?

  Demand Characteristics

  Social Desirability Bias
• What is demand characteristics?

  Where the participants guess the aim of the study and as a result change there behaviour: either to please the researcher (please-you effect) so they get the result they want or to ruin the researchers results(screw-you effect)
• What Is social desirability bias?

  Where participants feel they would be judged by the researcher in some way so try to present themselves in a more desirable light
• Investigators Effects

  When the individual conducting the research Influences the outcome of the study most often subconsciously
• How can you control researcher bias/investigator effects With a summery?


  Standardised Instructions = exact same instruction should be read in exactly the same way to each participant.

  Double Blind technique = both researcher and participant are unaware of what the condition the participants are in as they are made to look similar

  Randomisation = use of chance to control for the effects of bias when deciding things like order of conditions
• How do you limit participant reactivity?

  Signal blind Technique = Where the participants are unaware of the conditions they are in

  Depiction - lead your participants to believe the research is about something other than it actually is or withhold the aim from the participants

  Change the type of experiment= laboratory experiments with there high levels of control are the most susceptible to participate reactivity due to the participants knowing they are being studied
• What is single blind technique?

   Where the participants are unaware of the conditions they are in
• What is Deception?

  lead your participants to believe the research is about something other than it actually is or withhold the aim from the participants 
• Changing the type of experiment?

  laboratory experiments with there high levels of control are the most susceptible to participate reactivity due to the participants knowing they are being studied