Define experimental design
How participants are used within a study
What are the 3 experimental designs?
- Independent groups
- Matched pairs
- Repeated measures
What is the name for groups who complete the study in a different way
Conditions
How many conditions can there be in a psychological study?
As many as is necessary
Explain “independent groups”
- The study uses completely separate, different groups of participants for each study
- Independent of eachother
Explain “matched pairs”
- Each group is independent of eachother
- Researcher matches up participants in one group with someone from the other group based on similar characteristics (e.g age, gender, IQ etc)
Explain “repeated measures”
- The study uses the same group of participants for each condition
- Used repeatedly in the study
Define participant variables
- Differences between participants within a group (e.g.
variation in age, sex or social background) - A kind of extraneous variable
Define extraneous variable
All variables, other than the independent variable, which
could affect the results
Define order effect
Refers to how the order of conditions can influence the outcome
What are the 3 order effects?
- Fatigue effect (are tired from the experiment the second time they do it)
- Boredom effect (are bored of the experiment the second time they do it)
- Practice effect (practice the experiment and do better a second time, or figure out the aim and change their behaviors)
What are demand characteristics?
When a participant figures out the aim of an experiment and acts in the way that they think they should
Define counterbalancing
- A method to reduce order effects
- Half of the participants do the conditions in a different order to the other half
Evaluate “independent groups”
Pros
- No order effects – because participants only take part in one condition, the results aren’t affected by practice, fatigue or
boredom – so the results are more genuine
Cons:
- Participant variables may have an effect on results
- More people are needed, so it is more effort and time-consuming
Evaluate “matched pairs”
Pros:
- Reduced participant variables, because the variation between
groups is lower
- Avoids order effects, so counterbalancing is not necessary
Cons:
- Can be very time consuming
- It is impossible to pair people up accurately enough!
Evaluate “repeated measures”
Pros:
- Fewer people are needed to take part
- Saves time and money
- Avoids participant variables distorting results
Cons:
- There is a higher chance of order effects occurring
(this can be corrected using
counterbalancing)
