Within Subjects Design - Research Methods in Psychology/Social Sciences

Summary

This educational video delves into the within-subjects experimental design, contrasting it with the between-subjects design. It explains the use of the same group of participants across different conditions, highlighting its advantages such as controlling for individual differences and requiring fewer participants. The script also addresses potential threats to internal validity, like environmental changes, time-related variables, and order effects, and suggests strategies like counterbalancing and pilot testing to mitigate these issues. It concludes with guidance on choosing between within-subjects and between-subjects designs based on factors like individual differences, treatment effects, and participant availability.

Takeaways

• 🔍 The within-subjects design involves the same group of participants being tested or observed under all different conditions of an experiment.
• 📚 A key advantage of within-subjects design is that it allows for the ultimate control of extraneous variables by reusing the same participants across conditions.
• 🕵️‍♂️ The study by Stephens et al. (2009) demonstrated that swearing can help individuals tolerate pain more effectively, illustrating the application of within-subjects design.
• 🧠 Schmidt's (1994) research on word recall showed that humorous sentences are more memorable than neutral ones, another example of within-subjects design.
• ⏱️ Time-related confounding variables, such as fatigue and practice effects, can influence the results in within-subjects designs where conditions are administered at different times.
• 🌡️ Environmental variables like room size or temperature can confound results if they change between conditions within a within-subjects design.
• 🔄 Order effects, such as carryover effects from one condition to another, can bias results in within-subjects designs if not properly controlled.
• 🔄 Counterbalancing the order of treatment conditions is a technique used to control for order effects in within-subjects designs.
• 👥 Within-subjects design requires fewer participants compared to between-subjects design, making it more efficient in terms of resources.
• ⚖️ The decision between using within-subjects or between-subjects design should be based on factors like anticipated individual differences, potential long-lasting treatment effects, and ease of participant recruitment.

Q & A

What is a within-subjects design in experimental psychology?

A within-subjects design is an experimental approach where the same group of participants is tested or observed under all the different conditions being compared. This design allows for each individual's performance to be compared across various conditions, making the group synonymous with conditions.

Why might a researcher choose a within-subjects design over a between-subjects design?

A researcher might choose a within-subjects design to control for individual differences, as each participant serves as their own control by being exposed to all conditions. This design is also advantageous when the number of available participants is limited.

What was the main finding of the study by Stephens and colleagues in 2009 on swearing and pain tolerance?

The study found that swearing or cursing can make it easier for individuals to tolerate pain, suggesting that expressing emotions through swear words can help people cope with discomfort.

How did Schmidt's 1994 study differ from the study by Stephens and colleagues in terms of within-subjects design?

Schmidt's study alternated between funny and neutral words, administering all treatments together, while Stephens and colleagues had a time gap between the neutral word and swear word conditions, exposing participants to one condition at a time.

What are the potential threats to internal validity in a within-subjects design?

Threats to internal validity in a within-subjects design include confounding from environmental variables, time-related confounding variables, history, maturation, instrumentation, regression towards the mean, and order effects.

What is the concept of 'counterbalancing' in the context of within-subjects designs?

Counterbalancing is a technique used to control order effects by changing the order in which treatment conditions are administered across different participants, ensuring that the order of conditions does not influence the study's results.

Why might a within-subjects design require fewer participants compared to a between-subjects design?

A within-subjects design requires fewer participants because the same individuals are tested under all conditions, eliminating the need to recruit separate groups for each condition, thus saving time and resources.

What are some strategies to mitigate the effects of practice and fatigue in a within-subjects design?

Strategies to mitigate practice and fatigue effects include conducting pilot tests to understand their impact, shortening the duration of the experiment, and considering alternative designs such as between-subjects if within-subjects design poses too many challenges.

How can a researcher determine whether to use a within-subjects or a between-subjects design for their study?

A researcher can determine the appropriate design by considering factors such as anticipated individual differences, potential long-lasting effects of treatments, ease of recruiting participants, and the specific requirements and goals of their study.

What are the advantages and disadvantages of using a within-subjects design?

Advantages include controlling for individual differences and requiring fewer participants. Disadvantages include potential practice effects, fatigue, mortality (participant dropout), and the need for participant commitment over an extended period.