Extraneous Variables Flashcards
What is an extraneous variable?
Any variables (other than the IV) that could have an effect on the DV if not controlled. They are present in both conditions (unlike confounding) and therefore do not vary systematically.
What are participant variables?
Refers to differences between the participants which might affect their performance.
Examples: personality, intelligence, age, how they feel that day, how much sleep etc.
Most likely to occur using independent measures design.
How can we deal with participant variables?
• use a repeat measures design or a matched pairs design instead of an independent measures design.
•if an independent measure must be used, use random allocation.
What is a situational variable?
Refers to the setting and circumstances of the research which may affect the performance of the participants.
Examples: the difference in time of day, room carried out in, prompts given.
How can we overcome situational variables?
Standardisation - keeping the variables constant for all participants in all conditions.
The procedures and instructions for all participants are the same so they all experience the same situational variables. Won’t affect accuracy.
What is participant reactivity?
Refers to the behaviour of the participants changing due to their awareness that they are being studied.
Give the two types of participant reactivity.
Demand characteristics - where participants guess the aim of the study and change their behaviour.
Social desirability bias - feel they will be judged so present themselves in a more desirable light.
How can we overcome participant reactivity?
Single blind technique - participant is unaware of the condition they are in (placebo)
Deception - lead the participants to believe the research is about something other than what it actually is
Change the type of experiment - study their everyday life in their every day environment rather than a lab.
What are investigator effects?
Refers to when the investigator themselves influences the outcomes of the study.
How can we avoid investigator effects.
Standardised instructions - exactly the same instructions repeated for each participant (e.g script)
Double blind technique - both the participants and the investigator are unaware of which condition the participants are in. Third party researcher needed.
