Hockenbury Discovering Psychology 5th txtbk

32 CHAPTER 1 Introduction and Research Methodsnatural experimentA study investigating the effects of anaturally occurring event on the researchparticipants.Does Chronic Exposure to Noise ProduceStress? How could psychologists experimentallydetermine whether prolongedexposure to noise caused stress or otherharmful effects in children? Obviously, psychologistscould not ethically expose childrento potentially harmful levels of noisefor even brief periods of time. In an ingeniousstudy, Gary Evans and his colleagues(1998) used a technique called a naturalexperiment to compare levels of stress inchildren before and after a noisy airportwas built within earshot of their elementaryschool near Munich, Germany.In combination, the ginkgo biloba experiment and the hotel experiment demonstratethe powerful influence that can be played by people’s beliefs and expectations.Could beliefs and expectations play a role in the testimonials of people who hail theeffectiveness of unproven magnetic products, such as rings, bracelets, vests, andmattresses? Absolutely.But other factors could also be involved in the changes that people often reportin response to pseudoscientific products or procedures, such as magnet therapy orsubliminal motivation CDs (see Chapter 3). For example, the body’s natural healingprocesses can produce changes with the simple passage of time. Further, manypsychological or physical conditions cycle up and down, leading to temporary improvements.In later chapters, we’ll look at other factors that can contribute to anappearance of effectiveness in unsupported pseudoscientific claims.Variations and Limitations of ExperimentsA well-designed and carefully executed experiment can provide convincing evidenceof a cause-and-effect relationship between the independent and dependent variables.But experiments can have their own kinds of limitations or drawbacks, suchas difficulties manipulating the variables. Consider trying to test the effectiveness ofmagnet therapy in an experiment with a placebo control group. Using any metal object,such as a paper clip, participants can (and do) try to determine if they are usingthe real or sham magnets (Finegold & Flamm, 2006).Another potential limitation of experiments is that they are often conducted inhighly controlled laboratory situations. Because of this, the results may not generalizewell beyond the people who participated in the experiment. In other words, theresults may not represent what happens in real-world situations or to a more generalpopulation. To minimize this, experiments are sometimes carried out in naturalsettings, as was done in the hotel experiment.Another potential limitation is that the phenomena the researchers want to study areimpossible or unethical to control experimentally. For example, a psychologist mightwant to know whether prolonged exposure to a noisy urban environment creates psychologicaland physical stress in young children. Obviously, it would be unethical to subjectchildren to loud noise for a prolonged (or even a short) period of time.But researchers are sometimes presented with the opportunity to study such phenomenaby taking advantage of naturally occurring events. In a natural experiment,researchers carefully observe and measure the impact of a naturally occurring event ontheir study participants (Rutter, 2008). Although it is not a true experiment, naturalexperiments can be used to study the effects of disasters, epidemics, or other events.Psychologist Gary Evans and his colleagues (1998) used the natural experimentstrategy to study the effects of chronic noise exposure on children. They comparedstress levels in elementary school children before and after a large international airportwas built in their once quiet community near Munich, Germany. The researchersmeasured both physical and psychological indicators of stress, such as blood pressure,levels of stress hormones, and perceptions of the daily quality of life. They also measuredthe same indicators over the same time period in a matched control group of childrenliving in a community that remained quiet. The results? The children who wereexposed to chronic noise (the independent variable) showed increased psychologicaland physical stress (the dependent variable). In contrast, the control group children,who were not exposed to constant noise, showed little change in stress. Later researchshowed that children living near an older airport that was closed after the new airportopened benefited from their newly quiet environment: Reading ability and memoryimproved (Evans & Hygge, 2007; Hygge & others, 2002).Before leaving the topic of research methods, one contemporary trend deserves specialmention: the increasing use of brain-imaging techniques in virtually every area ofpsychology. To help highlight the importance of neuroscience, every chapter includesa special “Focus on Neuroscience” feature. This chapter's Focus on Neuroscience exploresbrain-imaging techniques and discusses their increasing use in psychological research(see pp. 34-35).