Fatigue Effect

Practice Effect

Context Effect

Rule of Thumb for Experimental Design Choice

In a taste-testing experiment, participants first drink a highly sweetened, strongly flavored soda and then immediately taste a mild, lightly flavored sparkling water. If the intense sweetness of the first drink temporarily dulls their taste buds and alters how they perceive the sparkling water, what is this confounding variable called?

Arrange the following steps in the correct chronological order to illustrate how a carryover effect functions as a confounding variable in a within-subjects experiment.

In within-subjects research, it is critical to distinguish between specific lingering influences and general changes over the course of a study. Match each research scenario to the type of confounding effect it illustrates.

A researcher studying the effects of two different caffeine-based energy drinks on reaction time has the same group of participants consume Drink A and then, 20 minutes later, consume Drink B. The researcher's conclusion that Drink B is more effective because reaction times were faster after the second drink is a valid scientific evaluation, as testing the same participants ensures that the independent variable is the only factor influencing the results.

Which of the following best describes a carryover effect?

True or False: Carryover effects are problematic in research because they create a plausible alternative explanation for the data, preventing the researcher from concluding that the independent variable caused the observed change in behavior.

A(n) _____ effect occurs when a participant's behavior or response in one experimental condition is directly influenced by having been tested in a prior condition.

A researcher is designing a within-subjects experiment and must think carefully about how carryover effects interact with various design strategies. Match each design feature or scenario on the left to the statement on the right that correctly describes its relationship to carryover effects.

A within-subjects study compares reading comprehension scores under a loud rock-music condition and a silence condition. After data collection, the researcher discovers that comprehension scores in the silence condition are significantly lower only when silence follows the rock-music condition—not when it precedes it. By analyzing this asymmetry, the researcher concludes that this pattern reflects a carryover effect rather than a fatigue effect, because the impaired performance in the silence condition is specifically traceable to the direct influence of the _____ on participants' cognitive state, rather than to a general decline resulting from the cumulative burden of repeated testing.

A researcher wants to compare risk-taking behavior after participants watch either a high-arousal action film or a low-arousal nature documentary. She is deciding whether a within-subjects design with counterbalancing or a between-subjects design better protects internal validity. Arrange the following evaluative reasoning steps in the correct order for making and justifying this design decision in light of potential carryover effects.

Define a carryover effect and explain why it can pose a problem as a confounding variable in psychological research when it is not the primary focus of a study.

Based on this scenario, explain how the carryover effect functions as a confounding variable in this experiment and why this makes it difficult for the researcher to draw a clear conclusion about the effectiveness of Study Technique B.

A cognitive psychologist is designing a within-subjects experiment comparing two memory strategies, Strategy X and Strategy Y. Applying the rule of thumb for experimental design choice, what two conditions must the psychologist check to justify using a within-subjects design with proper counterbalancing?