Carryover Effects in Research Design

What type of threat to internal validity was described in this example?

a. Sampling effects

b. Carryover effects

c. Participant attrition

d. Participant fatigue

Answer: b. Carryover effects

From the question, we are informed about a researcher who uses a within-subjects design in which one group completes a difficult puzzle and the second group completes an easy puzzle. He finds that participants who completed the difficult puzzle first were able to learn about the puzzle and completed the easy puzzle quicker, compared to participants who did the easy puzzle first.

In this case, the type of threat to internal validity described was Carryover effects. A carryover effect can be regarded as an effect that is carried over from one experimental condition to another. It is any lingering effect resulting from a previous experimental condition that has an impact on the current experimental condition.

A common type of carryover effect is known as a practice effect. In this effect, participants perform a task better in later conditions since they had a chance to practice it in the past.