An article entitled "Study Offers Surprise on Working of Body's Clock" tells about a randomized controlled double-blind study in which subjects spent several days in a sleep lab. At night they "stayed awake in a dimly lighted room, reclining in a chair with a table over their laps. A thick black material was draped over their legs and fastened to their waists. Underneath this skirt, a knee pad with a fiber optic tube was attached to the back of their knees and a bright light was delivered through the tube for three hours."25 Other subjects were kept under identical conditions except the light was not turned on. Those treated with light had significant changes in their body rhythms, while those untreated did not.

a. Which of these would be most worrisome in this experiment: placebo effect, experimenter effect, lack of realism, or imposing a treatment that is unethical?

b. Was the black skirt used to offset the placebo effect, the experimenter effect, lack of realism, or imposing a treatment that is unethical?

c. If body rhythms are assessed by measuring body temperature and level of melatonin in the blood, is it important for researchers to be unaware of which subjects were in the treatment group when it comes time to evaluate their responses?