Control of Variables Flashcards
What is an extraneous variable?
- A variable that might affect the DV other than the IV
How do we control these variables?
- Carefully controlling main areas of studies where EV are likely to arise
How do we control EV in Test Materials?
- The researcher should use a standardised test to ensure validity of the behaviours measured
- For Example, if an experimenter used repeated measures design whereby a participant does both Condition A (words) , & Condition B (words and photos) for recall of words then the tests in each conditions must be different but similar words to ensure its not memory but the technique that is being researched (photos)
How do we control EV in Participant Variables?
- In an experiment where the participants characteristics aren’t being measured (age, gender) then these must be controlled
- All participants must be women aged 20-25 with an IQ of 100-110 to reduce EV affecting the DV
How do we control EV in Situational Variables?
- Experiment settings and surroundings must be controlled
- Temperature, noise levels objects in the room
- All EV may affect the DV for one participant than it does for the other so must be controlled
How do we control EV in Experimenter Variables?
- Personality, appearance and conduct of the researcher must be controlled as this can impact performance of the participants
- A female researcher may affect a males response to a sexist question
What are demand characteristics?
- An EV in experimental research and one that’s difficult to control
- Guessing the purpose of the research and trying to please the researcher by giving “correct” results or giving “wrong” results to either please the researcher or screw the researcher
- Acting unnatural due to fear is abnormal
- Acting unnatural in order to look good is social desirability
When are demand characteristics likely to occur?
- A lab study
- A repeated studies design
- When participants know aim of study
- When participants know they are being studied
What is Repeated measures design?
- Participants takes part in both of the experimental conditions
- Allowing comparisons between condition 1 and 2
- Participants may guess the aims of the investigation and show the please you or screw you effect
- Validity will be reduced as the participants may guess the aims and change behaviour
How would Participant awareness show demand characteristics?
- Participant is more likely to change their behaviour when they are aware of the aims
- To deal with this researchers use deception so they don’t know the true aims
How would Participant awareness being studied show demand characteristics?
- If we know that we are being studied then we behave unnaturally
- Thereby participants aren’t displaying the behaviour that the researcher would like to measure
- So the validity of the findings is reduced
What is the Single-Blind technique?
- Specific research procedure in which the researcher does not tell the participants if they are being given a test, treatment or control treatment
What are investigator effects?
- Cues from an investigator that encourages certain behaviours in the participant
- This acts as an EV and reduces the validity of findings
- Physical characteristics
- Personal characteristics
- Experimenter expectancy
-This is when what the investigator knows about a participant affects how they think about or judge them.
How do we deal with investigator effects?
Double-blind technique
- This is when neither the investigator or participant knows the condition which the participant has been assigned to
What is Randomisation?
- A technique used to minimise the effects of EV on the outcome
- Using chance to reduce the researchers influence on the design of the investigation
- Can be used to determine which participants are assigned to which condition
- Determine the test materials used
What is standardisation?
- All participants should be subject to the same environment, information and experience
- Including standardised instructions
What is counterbalancing?
- Used in a repeated measures design
- A problem is the order of the conditions of the experiment
- Participants may perform better on the second condition due to practice or may do worse due to boredom or fatigue
- Counterbalancing ensures that each condition is tested first or second in equal amounts
- ABBA, Participant 1 does Con A then Con B, Participant 2 does Con B then Con A
What are Pilot Studies?
- Small scale trial run of an experiment before doing the real investigation
- Ensures all test materials are useful and the correct participants are being represented
