Hockenbury Discovering Psychology 5th txtbk

280 CHAPTER 7 Thinking, Language, and IntelligenceAre These Mammals? The more closely anitem matches the prototype of a concept,the more quickly we can identify the itemas being an example of that concept.Because bats, walruses, and the ratherpeculiar- looking African long-tailedpangolin (center) don’t fit our prototypefor a mammal, it takes us longer to decidewhether they belong to the category“mammal” than it does to classify animalsthat are closer to the prototype.Table 7.1From Prototypes to AtypicalExamplesVehiclescartruckbusmotorcycletraintrolley carbicycleairplaneboattractorcartwheelchairtankraftsledhorseblimpskateswheelbarrowelevatorSource: Rosch & Mervis (1975).FruitorangeapplebananapeachpearapricotplumgrapestrawberrygrapefruitpineappleblueberrylemonwatermelonhoneydewpomegranatedatecoconuttomatooliveThe first items listed under each generalconcept are the ones most people tend tothink of as the prototype examples of thatconcept. As you move down the list, theitems become progressively less similar tothe prototype examples.such as geometric shapes. These defining rules or features can be simple or complex.In either case, the rules are logical but rigid. If the defining features, or attributes,are present, then the object is included as a member or example of that concept. Forsome formal concepts, this rigid all-or-nothing categorization procedure works well.For example, a substance can be categorized as a solid, liquid, or gas. The rulesdefining these formal concepts are very clear-cut.However, as psychologist Eleanor Rosch (1973) pointed out, the features thatdefine categories of natural objects and events in everyday life are seldom as clearcutas the features that define formal concepts. A natural concept is a conceptformed as a result of everyday experience rather than by logically determiningwhether an object or event fits a specific set of rules. Rosch suggested that, unlikeformal concepts, natural concepts have “fuzzy boundaries.” That is, the rules orattributes that define natural concepts are not always sharply defined.Because natural concepts have fuzzy boundaries, it’s often easier to classify somemembers of natural concepts than others (Rosch & Mervis, 1975). To illustrate thispoint, think about the defining features or rules that you usually associate with thenatural concept “vehicle.” With virtually no hesitation, you can say that a car, truck,and bus are all examples of this natural concept. How about a sled? Wheelbarrow?Raft? Elevator? It probably took you a few seconds to determine whether theseobjects are also vehicles. Why are some members of natural concepts easier toclassify than others?According to Rosch (1978), some members are better representatives of a naturalconcept than are others. The “best,” or most typical, instance of a particularconcept is called a prototype (Mervis & Rosch, 1981; Rosch, 1978). According toprototype theories of classification, we tend to determine whether an object is aninstance of a natural concept by comparing it to the prototype we have developedrather than by logically evaluating whether the defining features are present orabsent (Minda & Smith, 2001).The more closely an item matches the prototype, the more quickly we can identifyit as being an example of that concept (Rosch & Mervis, 1975). For example,it usually takes us longer to identify an olive or a coconut as being a fruit becausethey are so dissimilar from our prototype of a typical fruit, like an apple or an orange(see Table 7.1).Some researchers believe that we don’t classify a new instance by comparing itto a single “best example” or prototype. Instead, they believe that we store memoriesof individual instances, called exemplars, of a concept (Nosofsky & Zaki,2002; Voorspoels & others, 2008). Then, when we encounter a new object, wecompare it to the exemplars that we have stored in memory to determine whetherit belongs to that category. So, if you’re trying to decide whether a coconut is afruit, you compare it to your memories of other items that you know to be fruits.Is it like an apple? An orange? How about a peach? Or a cantaloupe?