Psychology Chapter: Repeated Measures Design

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Questions and Answers

What is a key benefit of using a repeated measures design?

It is less powerful than between-subject designs.

It requires more participants.

It eliminates noise from individual differences. (correct)

It can only test one condition at a time.

Which of the following statements about within-subject designs is true?

They are often used in cognitive experiments. (correct)

They can be designed for any research question.

They always yield lower statistical power.

They involve multiple groups of participants.

In the context of the target search study, what does 'DV' stand for?

Dependent Variable (correct)

Diversity Variable

Dynamic Verification

Design Variable

What distinguishes a target search task from a simple within-subject experiment?

It incorporates multiple types of distractors. Signup and view all the answers

Why might research using a within-subject design have very few participants?

Each participant undergoes multiple conditions. Signup and view all the answers

In a complex target search task, what is the correct identification of the target?

The blue X only. Signup and view all the answers

What is a limitation of within-subject designs?

They may lead to order effects. Signup and view all the answers

What variable was used as a measure of success in the repeated measures design discussed?

Total amount of time taken to react. Signup and view all the answers

What is the main advantage of using a within-subject design?

Reduces variability caused by individual differences Signup and view all the answers

Which situation is best suited for an independent groups design?

When sequence effects cannot be managed Signup and view all the answers

What is the recommended course of action if the sequence effect cannot be accounted for in within-subject design?

Switch to a between-subject design Signup and view all the answers

How many possible order combinations can there be for 5 conditions using a within-subjects design?

120 Signup and view all the answers

What is a potential drawback of a within-subject design related to participant awareness?

Participant bias due to hypothesis awareness Signup and view all the answers

What is recommended when the number of conditions is large in an experiment?

Use random selection for condition presentation Signup and view all the answers

Why is a within-subject design considered more sensitive to small group differences?

It reduces participant variability across conditions Signup and view all the answers

In a study examining the impact of bright versus dim light on memory, what type of design is most suitable?

Within-subject design if timing can be controlled Signup and view all the answers

What is a sequence effect in the context of within-subject design?

The effect of one condition on performance in subsequent conditions Signup and view all the answers

What is a positive practice effect?

An improvement in performance due to prior exposure to similar tasks Signup and view all the answers

Which method can be used to mitigate sequence effects in experiments?

Implementing counterbalancing Signup and view all the answers

What does a carryover effect refer to in experimental design?

Effects from one condition impacting subsequent conditions Signup and view all the answers

How many variations are available for presenting three conditions in a within-subject design?

6 Signup and view all the answers

What is a common solution to mitigate negative practice effects?

Implementing a sufficient rest period between trials Signup and view all the answers

In which situation might a within-subject design be considered undesirable?

When strong carryover effects are likely to occur Signup and view all the answers

Which scenario is unlikely to produce a positive practice effect?

A participant experiences fatigue from continuous tasks Signup and view all the answers

Study Notes

Repeated Measures Design

Each participant takes part in all conditions of the experiment.
Participants complete the dependent variable measure in all conditions.
Also known as a "within-subject" design.
The entire experiment is conducted "within" each subject.
Refers to the same group of participants in all conditions.
The independent groups design (from previous chapters) is also called a "between-subject" design.

Within-Subject Designs

Only one group of participants participates in a within-subject design.
Eliminates "noise" from individual differences.
Frequently seen in cognitive experiments.
Studies such as reaction time studies often use within-subject designs.

Example: Target Search Study

Participants search for a specific target (e.g., a blue X) among distractors (other letters).
Variables include the number of distractors, the color of the target, and the shape of the target.
The dependent variable is reaction time (time to locate and click on the correct target).
Within-subject designs often use a small number of participants.

Design Procedure

Participants complete all conditions of the experiment one after the other.
For example, in a target search study with three conditions (10 distractors, 15 distractors, 20 distractors), participants might complete the 10 distractor condition first, then the 15 distractor condition, and finally the 20 distractor condition.
The order of conditions can vary for different participants.

Results

Results are often displayed in a table showing each participant's performance on each condition.
The table includes participant number, condition order, and scores (e.g., reaction times).

Sequence Effect

The experience of one condition can affect performance on subsequent conditions.
This is called sequence effect, and it can be a challenge in within-subject designs.
Sequence effect can be either positive (practice effect) or negative (fatigue effect).
Positive Practice Effect (Training Effect): Improvement in performance as a result of experience with a task.
Negative Practice Effect (Fatigue, Boredom): Deterioration in performance as a result of repeated exposure to a task.
Carryover Effect: The effect from one condition that carries over to the next condition. This can occur when a treatment effect from one condition persists into subsequent conditions.

Solutions to Sequence Effect

Counterbalancing: A systematic way to control for sequence effects.
Random Selection Presentation: Randomly selecting the order of conditions for each participant. This is particularly useful when there are many conditions.

Counterbalancing

In a three-condition experiment, there are six possible presentation orders (ABC, ACB, BAC, BCA, CAB, CBA).
Each participant is assigned a different presentation order, systematically varying their order of exposure.
The number of participants should be a multiple of the number of presentation orders.

Random Selection Presentation

For complex experiments with many conditions, it may be impractical to exhaust all possible presentation orders.
Instead, random selection presentation is used.
A computer program can randomly select the next condition to be presented to each participant.

Strengths of Within-Subject Designs

More sensitive to small group differences.
Variability caused by individual differences is eliminated or reduced.
Fewer participants are needed, leading to increased power.
Less time is spent on instructions.

Weaknesses of Within-Subject Designs

Participants might figure out the hypothesis (subject effect).
Sequence effects can be difficult to control and can bias results.
If sequence effects cannot be controlled by the design, a within-subject design is not appropriate.

When to Use Within-Subject or Between-Subject Designs

The decision of whether to use a within-subject or between-subject design depends on the potential for sequence effects.
If sequence effects can be controlled, a within-subject design is advantageous.
If sequence effects cannot be controlled, a between-subject design is more appropriate.

Examples to Consider

Research question 1: Does exposure to different information about capital punishment affect people's opinions?
- A within-subject design could be used to expose participants to arguments in favor and against capital punishment. However, participants might remember the arguments from one condition, potentially influencing their responses in later conditions. A between-subject design would be more appropriate.
Research question 2: Does bright light improve memory performance compared to dim light?
- A within-subject design could be used where participants are tested in both bright and dim light conditions. However, being tested in one condition first might affect performance in the subsequent condition due to fatigue or learning effects.

Key Take Away

Within-subject designs can be powerful to study relationships between variables but they come with specific challenges to consider.
The key is to use the appropriate design that minimizes bias and accurately reflects the relationship between variables.

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Description

Explore the principles of repeated measures design in psychology experiments. This quiz delves into within-subject designs, highlighting their advantages in minimizing individual differences and their application in studies, such as reaction times. Test your understanding with examples and key concepts from the chapter.