Hockenbury Discovering Psychology 5th txtbk

Perception115To identify the mysterious object, you must interpret the sensory data. Topdownprocesses help you identify the large green blotch as a Christmas tree—a conclusionthat you probably would not reach if you had no familiarity with the waymany Americans celebrate the Christmas holiday. The Christmas tree branches,ornaments, and lights are just fuzzy images, but other images work as clues—ahappy child, a stuffed bear with a red-and-white stocking cap. Learning experiencescreate a conceptual knowledge base from which we can identify and interpret manyobjects, including kids, cats, and Christmas trees.Clearly, bottom-up and top-down processing are both necessary to explain howwe arrive at perceptual conclusions. But whether we are using bottom-up or topdownprocessing, a useful way to think about perception is to consider the basic perceptualquestions we must answer in order to survive. We exist in an ever-changingenvironment that is filled with objects that may be standing still or moving, just likeourselves. Whether it’s a bulldozer or a bowling ball, we need to be able to identifyobjects, locate objects in space, and, if they are moving, track their motion. Thus,our perceptual processes must help us organize our sensations to answer threebasic, important questions: (1) What is it? (2) How far away is it? and (3) Where isit going?In the next few sections, we will look at what psychologists have learned aboutthe principles we use to answer these perceptual questions. Much of our discussionreflects the work of an early school of psychology called Gestalt psychology,which was founded by German psychologist Max Wertheimer in the early 1900s.The Gestalt psychologists emphasized that we perceive whole objects or figures(gestalts) rather than isolated bits and pieces of sensory information. Roughlytranslated, the German word Gestalt means a unified whole, form, or shape.Although the Gestalt school of psychology no longer formally exists, the pioneeringwork of the Gestalt psychologists established many basic perceptual principles(S. Palmer, 2002).The Perception of ShapeWhat Is It?When you look around your world, you don’t see random edges, curves, colors, orsplotches of light and dark. Rather, you see countless distinct objects against avariety of backgrounds. Although to some degree we rely on size, color, and textureto determine what an object might be, we rely primarily on an object’s shape toidentify it.Figure–Ground RelationshipHow do we organize our perceptions so that we seean object as separate from other objects? The earlyGestalt psychologists identified an important perceptualprinciple called the figure–ground relationship,which describes how this works. When we view ascene, we automatically separate the elements ofthat scene into the figure, which is the main elementof the scene, and the ground, which is itsbackground.You can experience the figure–ground relationshipby looking at a coffee cup on a table. The coffeecup is the figure, and the table is the ground.Notice that usually the figure has a definite shape,tends to stand out clearly, and is perceptually meaningfulin some way. In contrast, the ground tends tobe less clearly defined, even fuzzy, and usually appearsto be behind and farther away than the figure.Max Wertheimer (1880–1943) Arguingthat the whole is always greater than thesum of its parts, Wertheimer foundedGestalt psychology. Wertheimer and otherGestalt psychologists began by studyingthe principles of perception but laterextended their approach to other areasof psychology.Gestalt psychology(geh-SHTALT) A school of psychologyfounded in Germany in the early 1900s thatmaintained that our sensations are activelyprocessed according to consistent perceptualrules that result in meaningful wholeperceptions, or gestalts.figure–ground relationshipA Gestalt principle of perceptual organizationthat states that we automatically separatethe elements of a perception into the featurethat clearly stands out (the figure) andits less distinct background (the ground).Survival and Figure–GroundRelationships The natural camouflagethat protects some animals,like this Brazilian moth,from predators illustrates theimportance of figure–groundrelationships in survival. Whenan animal’s coloring and markingsblend with its background,a predator cannot distinguishthe animal (the figure) from itssurroundings (the ground). Inmuch the same way, militarypersonnel and equipment areoften concealed from enemyforces by clothing or tarps thatare designed to blend in withthe terrain, whether it bejungle, desert, forest, or snowymountain range.