Hockenbury Discovering Psychology 5th txtbk

The Experimental Method29The ginkgo biloba experiment illustrates that before any kind of treatment canbe claimed as effective, changes caused by placebo effect, practice effect, and otherinfluences must be identified. Only after accounting for changes caused by those effectscan you determine the main effect—the change that can be directly attributedto the treatment variable.The Hotel ExperimentCan Perceiving Work as Exercise Produce Health Benefits?Key Theme• Psychological research has found that a person’s beliefs and expectationscan exert a significant influence on health and well-being.Key Questions• What were the independent and dependent variables in Crum andLanger’s experiment?• What were the results in Crum and Langer’s hotel experiment?• What implications are suggested by the results in Crum and Langer’sexperiment?Testing for therapeutic effectiveness represents a classic experimental design involvinga placebo control group. Let’s look at a different experimental design,which was inspired by this clue from previous research: Elderly people who believedthat their health was “poor” were six times more likely to die than thosewho perceived their health as “excellent.” This pattern held true regardless oftheir actual state of physical health (Idler & Kasl, 1991).This association was found in a correlational study. More specifically, the researchersfound a positive correlation between “perception of health status” and“length of survival.” But as we explained earlier, correlational evidence cannot beused to draw conclusions about cause-and-effect relationships. Only an experimentcan provide the scientific evidence needed to show that a causal relationship existsbetween two variables.So how could you design an experiment to test the notion that a change in belief(the independent variable) produces a change in health (the dependent variable)?Ethically, of course, you could not conduct an experiment in which you deceivedpeople by telling them that their health had suddenly become “poor” or “good,”then waiting to see how long the participants survived. Besides, if you told peoplethat their health had changed for better or worse, they might start behaving differently—apotential confounding variable. Instead, the challenge in testing this notionwould be to just change a person’s beliefs without changing their behavior. Is thateven possible? Could it be done experimentally?placebo effectAny change attributed to a person’s beliefsand expectations rather than an actualdrug, treatment, or procedure; also calledexpectancy effect.random assignmentThe process of assigning participants toexperimental conditions so that all participantshave an equal chance of beingassigned to any of the conditions or groupsin the study.double-blind techniqueAn experimental control in which neitherthe participants nor the researchers interactingwith the participants are aware of thegroup or condition to which the participantshave been assigned.demand characteristicsIn a research study, subtle cues or signalsexpressed by the researcher that communicatethe kind of response or behavior that isexpected from the participant.practice effectAny change in performance that resultsfrom mere repetition of a task.main effectAny change that can be directly attributed tothe independent or treatment variable aftercontrolling for other possible influences.The Hypothesis and ParticipantsThat was the challenge faced by Harvard psychologists Alia Crum and EllenLanger. Crum and Langer (2007) wanted to test the hypothesis that changing aperson’s beliefs and expectations about the exercise benefits of a particular activitywould result in actual health benefits.The participants in Crum and Langer’s experiment were recruited from thehousekeeping staff at seven carefully matched hotels. All of the 84 women in thestudy cleaned an average of 15 hotel rooms per day, spending about 20 to 30 minuteson each room. Although you might not think of room cleaning as healthy physicalexercise, vacuuming, making beds, scouring bathrooms, bending, stooping, andpushing heavy supply carts requires a good deal of physical exertion.