Hockenbury Discovering Psychology 5th txtbk

116 CHAPTER 3 Sensation and PerceptionCRITICAL THINKINGESP: Can Perception Occur Without Sensation?ESP, or extrasensory perception, means the detection of informationby some means other than through the normal processesof sensation.Do you believe in ESP? If you do, you’re not alone. Recent surveysconducted by the Associated Press and the Gallup Poll havefound that close to 50 percent of American adults believe in ESP,including telepathy and clairvoyance (Fram, 2007; Moore, 2005).Forms of ESP include:• Telepathy—direct communication between the minds of twoindividuals• Clairvoyance—the perception of a remote object or event,such as sensing that a friend has been injured in a caraccident• Psychokinesis—the ability to influence a physical object,process, or event, such as bending a key or stopping a clock,without touching it• Precognition—the ability to predict future eventsThe general term for such unusual abilities is paranormalphenomena. Paranormal means “outside the range of normal ex -perience.” Thus, these phenomena cannot be explained byknown laws of science and nature. Parapsychology refers to thescientific investigation of claims of various paranormal phenomena.Contrary to what many people think, very few psychologistsconduct any kind of parapsychological research.Have you ever felt as if you had just experienced ESP? Considerthe following two examples:• Your sister was supposed to stop by around 7:00. It’s now7:15, and you “sense” that something has happened to her.Shortly after 8:00 she calls, informing you that she’s beeninvolved in a fender bender. Did you experience clairvoyance?• Some years ago, Sandy had a vivid dream that our cat Nubbingot lost. The next morning, Nubbin sneaked out the back door,went for an unauthorized stroll in the woods, and was gonefor three days. Did Sandy have a precognitive dream?The Ganzfeld TechniqueClairvoyance and telepathyexperiments often involveuse of the ganzfeld technique.The researchsubject lies in a quiet room,with his eyes covered byping-pong balls cut in half.White noise plays throughthe headphones coveringhis ears. Along with blockingextraneous sensorystimuli, this technique caninduce mild hallucinations insome subjects (Wackerman& others, 2008).Such common experiences may be used to “prove” that ESP exists.However, two less extraordinary concepts can explain both occurrences:coincidence and the fallacy of positive instances.Coincidence describes an event that oc curs simply by chance.For example, you have over a thousand dreams per year, most ofwhich are about familiar people and situations. By mere chance,some aspect of some dream will occasionally correspond withreality.The fallacy of positive instances is the tendency to remembercoincidental events that seem to confirm our belief about unusualphenomena and to forget all the instances that do not. For example,think of the number of times you’ve thought something happenedto someone but nothing did. Such situations are far morecommon than their opposites, but we quickly forget about thehunches that are not confirmed.Why do people attribute chance events to ESP? Research hasshown that believers in ESP are less likely to accurately estimate theESP (extrasensory perception)Perception of information by some meansother than through the normal processes ofsensation.Figure 3.13 Figures Have Shape, butGround Doesn’t Which shape in (b) canalso be found in (a)? The answer is thatboth shapes are in (a). It’s easy to spot thetop shape because it corresponds to one ofthe shapes perceived as a figure in (a). Thebottom shape is harder to find because it ispart of the ground or background of thetotal scene. Because we place more importanceon figures, we’re more likely tonotice their shape while ignoring theshape of background regions.Source: Rubin (2001).The early Gestalt psychologists noted that figure and ground have vastly differentperceptual qualities (N. Rubin, 2001). As Gestalt psychologist Edgar Rubin(1921) observed, “In a certain sense, the ground has no shape.” We notice theshape of the figure but not the shape of the background, even when that ground isused as a well- defined frame (see(a)(b)Figure 3.13). It turns out thatbrain neurons also respond differentlyto a stimulus that is perceivedas a figure versus a stimulusthat is part of the ground (Baylis& Driver, 2001). Particular neuronsin the cortex that respondedto a specific shape when it was theshape of the figure did not respondwhen the same shape was presentedas part of the background.