A researcher wants to know whether wearing sunglasses improves driving performance. In a properly designed WITHIN-subjects experiment, presence or absence of sunglasses would be varied by
A) randomly assigning half the drivers to a sunglasses condition and half to a no-sunglasses condition.
B) having all drivers first drive without sunglasses and then with sunglasses.
C) having half the drivers first drive without sunglasses and then with sunglasses and having the other half first drive with sunglasses and then without sunglasses.
D) having all drivers first drive with sunglasses and then without sunglasses.

Question

Quizplus · Accepted Answer

In a within-subjects experiment, the same participants are exposed to both conditions (with and without sunglasses). To control for order effects, half of the participants would start with the sunglasses condition and then switch to the no-sunglasses condition, while the other half would start with the no-sunglasses condition and then switch to the sunglasses condition. This is known as counterbalancing. Therefore, option C is the only one that follows this design. Option A is not appropriate because it does not control for individual differences in driving ability. Option B does not account for order effects. Option D could lead to a learning effect due to practice, making it difficult to determine whether any differences in driving performance are due to the sunglasses or simply due to increased familiarity with the driving task.

A Researcher Wants to Know Whether Wearing Sunglasses Improves Driving