Scientific Process - Control of Extraneous Variables Flashcards
Why do we need to control extraneous variables?
To prevent them from becoming confounding variables to ensure a study has validity
What are the different types of extraneous variables?
Order effects
Participant Variables
Environmental Variables
Investigator effects
Demand Characteristics
What are order effects?
When the order in which participants perform the conditions affects their performance
What are participant variables?
Difference in results of conditions is due to different people rather than the IV
What are environmental variables?
Factors in the environment which could affect the DV
What are investigator effects?
When the observer knows the aim of the study (and has bias)
When the interviewer influences the results of their research (age, gender…)
What are demand characteristics?
When participants guess the aim of the study and act accordingly
How can order effects be fixed?
Counterbalancing
How can participant variables be fixed?
Use the same people (higher chance of demand characteristics) or random allocation
How can environmental variables be fixed?
Standardisation of each condition
How can investigator effects be fixed?
Double blind technique
Standardised scripts
How can demand characteristics be fixed?
Single blind technique
What is random allocation?
Identify each participant with a number and randomly choose them until there is the required amount in each condition
What is standardisation?
Making sure all the conditions, materials and instructions are the same for each participant
What is the double blind technique?
When neither the participant nor the investigator knows the hypothesis of the study or what condition the participant is in
What are standardised scripts?
When the investigator acts in a similar way to each participant
What is the single blind test?
When the participants don’t know the aim of the study (difficult in repeated measures)
