The Flavor-Fusion Illusion

We obtained evidence on this by asking a few hundred Belgian and American college students, in a ques- tionnaire, whether they would be able to distinguish pairs of substances The Flavor-Fusion Illusion if they had lost their sense of smell. Students were generally accurate The Psychology of Flavor about the fact that they could distin- guish true tastes or oral irritation without the sense of smell, so they Paul Rozin correctly indicated that they could distinguish plain from sugar water University of Pennsylvania (79% correct), or pizza with hot pep- pers from pizza without hot peppers (76% correct). But they performed poorly on items where smell is criti- cal, that is, cases in which they would have great difficulty making a distinc- tion without the sense of smell. For here is no doubt that the most generally realize that a major part of example, 30 percent of subjects Timportant determinant of what they call “taste” is actually con- thought they could distinguish apple whether a person will like a particu- stituted by odors, brought to the juice from raspberry juice, 37 percent lar food is its flavor. The question brain on the olfactory nerve. Charac- thought they could distinguish coffee then is: what is flavor? In the broad- teristically, when older people say ice cream from chocolate ice cream, est sense, flavor is the perception of they have lost their sense of taste, and 43 percent thought they could what is in the mouth. This percep- they really mean that they have lost distinguish carrot puree from pea tion is an amalgam of information that aspect of flavor that is mediated puree. Hence, there is a lot of misin- about taste, oral somatosensory by the olfactory system. formation about the role of odor in events (texture and temperature) the perception of flavor. and smell. The odor information, for THE FLAVOR-FUSION The English language helps us to many foods the most critical compo- ILLUSION talk about this problem, because we nent of flavor, arrives at the olfac- People “refer” or “attribute” the have the word, “flavor,” which cap- tory receptors by a back-path, com- olfactory input to flavor to their tures the sense of a full mouth expe- ing from the mouth. This is called mouth, and to the food that they are rience. Our word “taste” can be the retronasal route (see Figure 1). consuming. I will call this the flavor thought to represent the more nar- Most research on the chemical fusion illusion, with the fusion occur- row set of experiences that arise senses is carried out by scientists ring between the olfactory, gustatory from the gustatory receptors in the whose primary interest is not food. and somatosensory inputs from the mouth. That is the way psychologist This explains the fact that there is a food. This illusion is quite robust: vir- use the term. However, people great deal of research about taste and tually everyone has experienced often use the word “taste” in a gen- smell, and virtually none about their head colds, which block access to the eral way, as equivalent to flavor. In combination in flavor. This lack of olfactory receptors, and noticed that normal usage, there is a tendency research on flavor is unfortunate for food doesn’t have much “taste.” The for the words “flavor” and “taste” two reasons: it limits the contribution inability to discriminate very differ- to be used in their technical sense. I that the sciences of chemical senses ent foods with the olfactory passages gave a group of native English can make to the understanding of the blocked has been demonstrated in speakers a set of sentence frames, of appreciation and selection of food the laboratory (Mozell et al., 1969), the general form: “I like the ______and it ignores one of the more inter- though common experience, includ- of raspberries” or “This has a bitter esting phenomena and illusions in the ing holding one’s nose while eating ______” (Rozin, 1982). They were area of perception. People do not will be adequate proof. asked to rate the appropriateness of Presented at the Pennsylvania Manufacturing Confectioners’ Association 50th Annual Production Conference

80 September 1996/The Manufacturing Confectioner