A researcher is investigating the effect of sleep deprivation on learning. She recruits 30 participants and randomly assigns half to a "no sleep" group and half to a "regular sleep" group. The "no sleep" group are required to stay up all night and report to a testing room at 2PM the following day. The "regular sleep" group are instructed to have a normal night's sleep and report to the testing room at 9AM the following day. Unfortunately, a water pipe broke outside the testing room window and there was noisy construction crew working the whole day of testing. Which of the following statements is true? a. The study may be affected by a situational variable. b. The construction noise may contribute to variability in test scores. C. The study has a confounding variable. The groups differ in the time they are to report to the testing room. d. All of these are true. QUESTION 18 You are conducting an experiment on the effect of reward on people's persistence in solving difficult math problems. In one condition, participants are told they will receive $20 for completing all the math problems. In the other condition, participants are told they will receive a chocolate (worth 5 cents) for completing all the math problems. The independent variable is and a sensible dependent variable would be type of reward promised; time spent on math problems b. difficulty of math problems; time spent on math problems C. pre-existing math ability; satisfaction with reward d-difficulty of math problems; satisfaction with reward QUESTION 19 You design a study to compare the influence of smoking and alcohol consumption on lung capacity. Therefore, lung capacity would be the... a. dependent variable b-reliability measure C. confound d-independent variable