Hockenbury Discovering Psychology 5th txtbk

Perception117probability of an event occurring by chance alone. Nonbelieverstend to be more realistic about the probability of events being theresult of simple coincidence or chance (Blackmore, 1985).Parapsychologists attempt to study ESP in the laboratory undercontrolled con ditions. Many initially convincing demonstrationsof ESP are later shown to be the result of research designproblems or of the researcher’s unintentional cuing of the subject.Occasionally, outright fraud is involved on the part of eitherthe subject or experimenter.Another problem involves replication. To be considered valid,experimental results must be able to be replicated, or repeated,by other scientists under identical laboratory conditions. To date,no parapsychology experiment claiming to show evidence of theexistence of ESP has been successfully replicated (Hyman, 1994;Milton & Wiseman, 2001).One active area of parapsychological research is the study ofclairvoyance using an experimental procedure called the ganzfeldprocedure (J. Palmer, 2003). (Ganzfeld is a German wordthat means “total field.”) In a ganzfeld study, a “sender” in oneroom attempts to com municate the content of pictures or shortvideo clips to a receiver in a separate room. Isolated from all contactand wearing goggles and headphones to block external sensorystimuli, the “receiver” attempts to detect the image that isbeing sent.One set of carefully controlled ganzfeld studies showed a“hit” rate that was well above chance, implying that some sortof transfer of information had taken place between sender andreceiver (Bem & Honorton, 1994). These results, published in awell-respected psychology journal, Psychological Bulletin, ledsome psychologists to speculate that there might be somethingto extrasensory perception after all—and that the ganzfeld proceduremight be the way to detect it. But other psychologists,like Ray Hyman (1994), argued that the study did not offer conclusiveproof that ESP had been demonstrated.Many ganzfeld studies have been published, some showingpositive results, some negative. Psychologists have used metaanalysisto try to determine whether the so-called ganzfeld effecthas been successfully replicated. The verdict? British psychologistsJulie Milton and Richard Wiseman (1999, 2001) concludedthat the ganzfeld effect has not produced replicable evidence ofan ESP effect in the laboratory. Other psycholo gists, however,dispute that conclusion with their own meta-analyses (Storm &Ertel, 2001). Most psychologists agree with Milton and Wiseman’s(2001) bottom line: “The final verdict on [ESP] dependsupon replication of an effect across experimenters undermethodologically stringent conditions.” To date, that bottomlinerequirement has not been met (J. Palmer, 2003).Of course, the history of science is filled with examples of phenomenathat were initially scoffed at and later found to be real. Forexample, the pain-relieving effects of acupuncture were initially dismissedby Western scientists as mere superstition or the power ofsuggestion. However, controlled studies have shown that acupuncturedoes effectively relieve pain and may be helpful in treatingother conditions (Ulett & Han, 2002; National Center for Complementaryand Alternative Medicine, 2002).So keep an open mind about ESP, but also maintain a healthysense of scientific skepticism. It is entirely possible that some dayconvincing experimental evidence will demonstrate the existenceof ESP abili ties (see Schlitz & others, 2006). In the final analysis,all psychologists, including those who accept the possibility ofESP, recognize the need for evidence that meets the requirementsof the scientific method.CRITICAL THINKING QUESTIONS Why do you think that people who believe in ESP are lesslikely to attribute events to chance than people who don’tthink ESP is a real phenomenon? Can you think of any reasons why replication might be particularlyelusive in research on extrasensory perception? Why is replication important in all psychological research, butparticularly so in studies attempt ing to prove extraordinaryclaims, like the existence of ESP?The separation of a scene into figure and ground is not a property of the actualelements of the scene at which you’re looking. Rather, your ability to separate a sceneinto figure and ground is a psychological accomplishment. To illustrate, look at theclassic example shown in Figure 3.14. This perception of a single image in two differentways is called a figure–ground reversal.Perceptual GroupingMany of the forms we perceive are composed of anumber of different elements that seem to go together(Prinzmetal, 1995). It would be more accurate to saythat we actively organize the elements to try to producethe stable perception of well-defined, whole objects.This is what perceptual psychologists refer to as“the urge to organize.” What principles do we followwhen we attempt to organize visual elements?parapsychologyThe scientific investigation of claims of paranormalphenomena and abilities.Figure 3.14 A Classic Exampleof Figure– Ground ReversalFigure–ground reversals illustratethe psychological nature of ourability to perceptually sort ascene into the main element andthe background. If you perceivethe white area as the figure andthe dark area as the ground,you’ll perceive a vase. If youperceive the dark area as thefigure, you’ll perceive two faces.