A Within-Subjects Experiment: Homophone Priming of Proper Names Within-Subjects Factorial Designs

1. A Within-Subjects Experiment: Homophone Priming of Proper Names Within-Subjects Factorial Designs Mixed Designs Advantages of Within-Subjects Designs Disadvantages of Within-Subjects Designs Controlling Within-Subjects Designs How Can You Choose a Design?

2. In a within-subjects experiment, subjects are assigned to more than one treatment condition. What is a within-subjects design? Introduction

3. Power is an experiment’s ability to detect the independent variable’s effect on the dependent variable. Explain the statistical concept of power. Introduction

4. Statistical power is desirable when it allows us to detect practically significant differences between the experimental conditions.Theoretically, there is a point of diminishing returns where excessive power detects meaningless differences between treatment conditions. Why is statistical power desirable? Introduction

5. For example, in a study of treatments to lower blood pressure, a difference of 0.1 mm Hg—while statistically significant—would not affect patient health or life expectancy. Why is statistical power desirable? Introduction

6. In a within-subjects experiment, researchers measure subjects on the dependent variable after each treatment. Why do we call this approach a repeated-measures design? Introduction

7. Subjects participate in more than one treatment condition and serve as their own control. We compare their performance on the dependent variable across conditions to determine whether there is a treatment effect. Summarize the basic principles of a within-subjects design. A Within-Subjects Experiment

8. A within-subjects factorial design assigns subjects to all levels of two or more independent variables. What is a within-subjects factorial design? Within-Subjects Factorial Designs

9. A mixed design is an experiment where there is at least one between-subjects and one within-subjects variable. What is a mixed design? Mixed Designs

10. Advantages: • use fewer subjects • save time on training • greater statistical power • more complete record of subjects’ performance What are the advantages of within-subjects designs? Advantages of Within-Subjects Designs

11. Disadvantages: • subjects participate longer • resetting equipment may consume time • treatment conditions may interfere with each other • treatment order may confound results What are the disadvantages of within-subjects designs? Disadvantages of Within-Subjects Designs

12. We can’t use a within-subjects design when one treatment condition precludes another due to interference. When can’t we use a within-subjects design? Disadvantages of Within-Subjects Designs

13. Order effects are positive (practice) and negative (fatigue) performance changes due to a condition’s position in a series of treatments. The term, progressive error, encompasses both positive and negative order effects. What is an order effect? Controlling Within-Subjects Designs

14. Counterbalancing is amethod of controlling order effects by distributing progressive error across different treatment conditions. How does counterbalancing control for order effects in within-subjects designs? Controlling Within-Subjects Designs

15. Two major counterbalancing strategies are subject-by-subject counterbalancing, which controls progressive error for each subject, and across-subjects counterbalancing, which distributes progressive error across all subjects. How does counterbalancing control for order effects in within-subjects designs? Controlling Within-Subjects Designs

16. A fatigue effect is form of progressive error where performance declines on the DV due to tiredness, boredom, or irritation. What is a fatigue effect? Controlling Within-Subjects Designs

17. Subject performance on the dependent variable may improve across the conditions of a within-subjects experiment and these positive changes are called practice effects. What are practice effects? Controlling Within-Subjects Designs

18. Practice effects may be due to relaxation, increased familiarity with the equipment or task, development of problem-solving strategies, or discovery of the purpose of the experiment. What are practice effects? Controlling Within-Subjects Designs

19. We can’t eliminate order effects because there is an order as soon as we present two or more treatments.Holding order constant—always assigning subjects to the sequence ABC—would confound the experiment. Why can’t we eliminate or hold order effects constant in a within-subjects experiment? Controlling Within-Subjects Designs

20. Subject-by-subject counterbalancingcontrols progressive error for each subject by presenting all treatment conditions more than once. Two subject-by-subject counterbalancing techniques are reverse counterbalancingand block randomization. What is the strategy of subject-by-subject counterbalancing? Controlling Within-Subjects Designs

21. In reverse counterbalancing, we administer treatments twice in a mirror-image sequence, for example, ABBA.When progressive error is linear, it progressively changes across the experiment so that A and B have the same amount of progressive error. How does reverse counterbalancing control progressive error? Controlling Within-Subjects Designs

22. Nonlinear progressive error, which can be curvilinear (inverted-U) or nonomonotonic (changes direction), cannot be graphed as a straight line. What is nonlinear progressive error? Controlling Within-Subjects Designs

23. Reverse counterbalancing only controls for linear progressive error. When progressive error increases in a straight line, this method actually confounds the experiment Why can’t reverse counterbalancing control for this? Controlling Within-Subjects Designs

24. Block randomization is a subject-by-subject counterbalancing technique where researchers assign each subject to several complete blocks of treatments. A block consists of a random sequence of all treatments, so that each block presents the treatments in a different order. What is block randomization? Controlling Within-Subjects Designs

25. Since subject-by-subject counterbalancing presents each treatment several times, this can result in long-duration, expensive, or boring procedures. This problem is compounded as the experimenter increases the number of treatments. What is a problem with subject-by-subject counterbalancing? Controlling Within-Subjects Designs

26. Across-subjects counterbalancingtechniques present each treatment once and controls progressive error by distributing it across all subjects. Two techniques arecompleteand partial counterbalancing. What are our alternatives? Controlling Within-Subjects Designs

27. Complete counterbalancing uses all possible treatment sequences an equal number of times. Researchers randomly assign each subject to one of these sequences. Explain complete counterbalancing. Controlling Within-Subjects Designs

28. Partial counterbalancingis a form of across-subjects counterbalancing, where we present only some of the possible (N!) orders.Two partial counterbalancing techniques are randomized partialand Latin square counterbalancing. Explain partial counterbalancing. Controlling Within-Subjects Designs

29. A within-subjects design is usually preferable when you need to control large individual differences or have a small number of subjects. However, it may not be feasible if the experiment is long or there is a risk of asymmetrical carryover. When is a within-subjects superior to a between-subjects design? How Can You Choose a Design?