Dr. Jones systematically varies the brightness in the laboratory (400, 800, and 1600 lumens) while holding other variables constant, and observes that the participants' activity level decreases as the brightness decreases. This illustrates ____.
A) a noncausal relationship between brightness and activity level
B) a causal relationship between brightness and activity level
C) no relationship between brightness and activity level
D) a nonsystematic relationship between brightness and activity level

Question

Quizplus · Accepted Answer

Dr. Jones is controlling for other variables and varying the independent variable (brightness) in order to observe its effect on the dependent variable (activity level). This demonstrates a causal relationship.

Dr Jones Systematically Varies the Brightness in the Laboratory (400