It is also known as a repeated measures design.
The term “treatment” describes the differentlevels of the independent variable, the variable that the experimenter controls.
In other words, all of the subjects in the study are treated with the critical variable in question.
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At a Glance
A within-subject design involves having all participants exposed to the exact same treatments.
It can be a helpful way for researchers to learn more about how changes happen over time.
By doing this, researchers can measure how each participant changes over time as a result of the treatment.
Let’s imagine that you are doing an experiment on exercise andmemory.
For your independent variable, you decide to try two different types of exercise: yoga and jogging.
Then, you have all the participants try jogging before taking a memory test.
What Is a 2x2 Within-Subjects Design?
A within-subjects design can also be a factorial design.
In a between-subjects design, people are only assigned to a single treatment.
So one group of participants would receive one treatment, while another group would receive a different treatment.
The differences between the two groups would then be compared.
Consider the earlier example of the experiment looking at exercise and memory.
In a between-subjects design, one group of participants would do yoga and take a memory test.
A different group of participants would jog and then take the memory test.
Recap
In a within-subjects design, all participants receive every treatment.
In a between-subjects design, participants only receive one treatment.
Each participant serves as their own baseline.
Participant Fatigue
Fatigueis another potential drawback of using a within-subject design.
Participants may become exhausted, bored, or less motivated after taking part in multiple treatments or tests.
Practice Effects
Finally, performance on subsequent tests can also be affected bypractice effects.
A within-subjects design is a great option if participants and resources tend to be limited.
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APA Dictionary of Psychology.Between-subjects design.
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