146 JOURNAL OF COSMETIC SCIENCE _ _ 10- 12- 18- 20 ß Adapting Odorant [] Control Odorant bl b2 al a2 rl r2 Test Session Figure 2. The effect of long-term exposure to an odorant on sensitivity as measured by olfactory thresholds. Ten subjects were exposed for two weeks in their home to a single odorant: half were exposed to isobornyl acetate (IBA) and half to citralva (C) at weekly intervals they were given threshold tests for their adapting odorant (IBA or C) and a control odorant (the alternate odor). bl and b2 refer to baseline tests, prior to odorant exposure al and a2 refer to tests during adaptation phase, and rl and r2 refer to tests following removal of the odorant from their home (recovery). Thresholds were significantly elevated to the exposure odorant, but not to the control odorant. Reprinted, by permission, from reference (24). CULTURAL EXPERIENCE AND THE PERCEPTION OF FRAGRANCE Anthropologists have observed that people of different cultures "inhabit different sensory worlds" (25-28). Thus, it is not surprising that cultural-specific experience can evoke different patterns of cognitive and emotional experience of an odor, and together, play a role in one's odor perception. Indeed, the available studies suggest that odor familiarity and dietary habits can influence both the identifiability and the perceived pleasantness of an odor. For example, more than 90% of American subjects (regardless of their ethnic background) correctly identified the odors of lemon and cherry (29), but only 23% of Taiwanese subjects correctly identified lemon odor (30) and only 65% of Japanese subjects correctly identified cherry odor (29). In addition, odors familiar to the Japanese (e.g., India ink, dried fish, roasted tea) were rated as more pleasant by Japanese than by German subjects (31). Conversely, odors familiar to the Germans (e.g., Catholic church incense, anise, almond) were rated more pleasant by Germans than by Japanese subjects.

FRAGRANCE PERCEPTION 147 Results from the 1986 National Geographic Smell Survey showed that a significantly larger number of Asians from Malaysia, Singapore, and Thailand said that they would eat something that smelled like mercaptan (an unpleasant rotten-egg smelling odor) than did the Caucasian respondents from those same countries (32), perhaps reflecting the prevalence of fermented foods in Asian diets. Odor familiarity may even influence the perceived intensity of an odor. For example, Japanese subjects perceived a familiar Japanese food odor, dried fish, as much less intense than did German subjects (31). Thus, just as culture-specific experience can account for some of the variation in both the sensory and hedonic response to odors, it can also play a major role in judgments of preference and appropriateness of fragrances for specific contexts. EXPECTATIONS, EMOTIONS, AND THE PERCEPTION OF ODORS Although any odor sensation is based, in part, on properties inherent in the chemical stimulus (e.g., concentration, quality), it can also be influenced by the mental set or expectations that we bring to any situation where odors are present. Odor detectability, perceived intensity, and even quality are meaningfully influenced by a variety of dif- ferent types of "top-down" information that can color the sensory information available from the odorant stimulus itself. For example, Knasko and colleagues (33) have shown that describing an aerosol application of deionized water as either a pleasant or unpleas- ant odorous substance produced reports of odor experience and mood effects that were congruent with the given hedonic characterization. And, in several studies that exam- ined more indirect influences of expectation on odor perception, adding color to an odorous solution increased the likelihood that an individual reported detecting the odor (34) and increased the perceived odor intensity (35). In a clear demonstration of the malleability of odor experience, Dalton and colleagues (36-38) have conducted a series of studies examining how information about the source and consequences of exposure to a volatile chemical influenced people's sensory and somatic response to an odor. In the basic paradigm, individuals were exposed in a chamber to a steady-state concentration of an odorant and were asked to rate the perceived intensity of odor and any sensory irritation (i.e., to eyes, nose, and throat) at regular intervals during exposure. Although all subjects were exposed to the same chemical, different groups were given different characterizing information about the odorant to which they would be exposed. Subjects assigned to a positive-bias condition were told that the odorant was a natural extract. In contrast, those assigned to a negative-bias condition were told that the odorant was an industrial chemical, while those assigned to a neutral-bias condition were given no characterizing information about the odorant. Perceived odor and irritation ratings were measured during exposure, and reports of health symptoms were obtained following exposure. In all cases, infor- mation provided to the subjects greatly influenced their reported odor experience during and following exposure (see Figure 3). Specifically, individuals exposed to the odorant under a "positive" expectation exhibited the most adaptation to odor and the lowest perceived irritation following exposure they reported the fewest health symptoms. In contrast, individuals given the negative expectation rated higher levels of odor intensity and reported the most overall irritation following exposure they reported significantly more health symptoms than the other groups. Similar results were observed when the