Just Taste It : Expectations , Experience , and their Timing as Determinants of Preferences

We examine two of the ways, direct and indirect, by which knowledge can influence preferences. In three experiments, patrons of a pub sampled and expressed their preferences between beer and beer with balsamic vinegar. The results showed preference for the vinegarbrew was lowest for those told upfront about the vinegar, and higher for those who were either unaware of the vinegar altogether, or informed about the vinegar after tasting the beers but before expressing their preferences. These results suggest that knowledge influences preference by modifying sensation (the indirect path). A fourth experiment demonstrates that respondents do not intuit the effect of information timing on preference. Expectations, Experience, and Preferences 3 Just Taste It: Expectations, Experience, and their Timing as Determinants of Preferences Cognitive psychologists have long understood that the phenomenology of experience is governed by both perceptual inputs arising in our sense organs (“bottom up processes”) and conceptual inputs arising in our brain, which can influence the processing or eventual interpretation of sensory input (“top down processes”). One well-known example illustrating both top-down and bottom-up processes is presented in Figure 1. This ambiguous figure, originally published in Harper's Weekly (Nov. 19, 1892), may be perceived as either a rabbit (facing left) or a duck (facing right), depending on whether the concept of rabbits or ducks is made accessible before viewing (Jastrow, 1899; Tsal & Kolbet, 1985). Such evidence supports the top-down process by showing that the same retinal stimulus can give rise to different perceptual experiences depending on the observer’s expectations. At the same time, it also supports the bottom-up process by showing the limits to such influences. Though plausibly interpretable as a rabbit or duck (or a hair dryer or drill), this “ambiguous” image will not be interpreted as a giraffe, a triangle, or Ronald Reagan, no matter how accessible such concepts are made in the higher cortical areas responsible for interpreting the retinal signal. Other examples that illustrate the joint effects of the bottom-up and top-down processes include evidence that the context of a visual scene strongly influences the speed and accuracy with which embedded objects are perceived (Biederman, 1972; Palmer, 1975), and that letters presented in the context of a word are more quickly recognized than those presented in isolation (Neisser, 1967). ••• Figure 1 ••• Expectations, Experience, and Preferences 4 The top-down vs. bottom-up distinctions can also be applied to analyses of preferences. For example, one’s consumption of food (and perhaps one’s perception of the way it tastes) is influenced by the actual chemical properties of the food, but also by the beliefs about other aspects of the food, including its nutritional properties or brand (Braun, 1999; Levin & Gaeth, 1988). For example, McClure et. al. (2004) found that Coke consumed from a cup labeled Coke was generally preferred to Coke consumed from an unlabeled cup (which respondents presumably thought was not Coke). They also found, in an fMRI study that if an image of a can of Coke was presented prior to its oral delivery (a squirt of Coke in the mouth), several brain areas were more highly activated than if Coke was consumed without this prior visual information regarding the identity of the sweet fluid being squirted into their mouth. The study by McClure et. al. (2004) is one of many showing that top down processes (e.g. information of brand identity) affect food preferences (Allison & Uhl, 1964; Bowen et. al., 1992; Levin & Gaeth, 1988). However, despite this research, it is, as yet, unclear whether conceptual inputs affect preferences directly as a separate input, independent from the taste experience (Figure 2A), whether it modifies the taste experience itself (Figure 2B), or whether it affects preferences in both ways (as illustrated in Figure 2C). ••• Figure 2 ••• For example, although the study by McClure et. al (2004) shows that brand knowledge activates brain structures not activated by the chemical contents of cola, it does not resolve whether the preference for the substance definitively identified as Coke occurs because the positive associations of the name provide a positive independent input for preferences (Figure 1 While the distinction of top-down and bottom-up is not always clear in the domain of preference construction, the working definition we will adopt here is that preferences constructed from conceptual knowledge (e.g. information about an experience) follows a top-down process, while preferences constructed from sensory input (e.g. the experience itself) follows a bottom-up process. Expectations, Experience, and Preferences 5 2A), or whether the taste per se is affected by the information (Figure 2B). The same ambiguity is evident in an earlier study by Allison and Uhl (1964), where 326 male beer drinkers sampled their favorite brand of beer and four other brands. When the beers were not labeled, all five brands received nearly identical taste ratings. However, when the drinkers knew which beers they were consuming, their favorite brand was rated significantly higher. Here, it is again unclear whether the elevated ratings reflected an enhanced gustatory experience per se, or whether the label information was another input causing consumers’ to rate their preferred brands higher. As a third example, Bowen et. al. (1992) found that consumers ate more ice cream if it was labeled as “high fat. ” Again, these results permit alternate interpretations. Perhaps high fat is associated with high quality and people are more willing to consume high quality treats (Figure 2A), or perhaps the high fat label enhances taste expectations, which in turn enhances the taste experience, leading to greater consumption (Figure 2B). Experimental Approach In three experiments, we attempted to determine which conceptualization of the top-down process best characterizes the manner in which knowledge influences preferences. In all three experiments, respondents consumed two beer samples: one unadulterated sample, and one sample of the “MIT brew,” which contained a few drops of balsamic vinegar—a beer condiment that most participants find conceptually offensive, but which does not, at this concentration, negatively influence the taste of beer (in fact, it slightly improves it). After tasting the two beer samples, respondents indicated their preference between them in a manner that varied across the 2 To verify this assumption, we asked 121 patrons of The Muddy Charles to assess how beer would taste if balsamic vinegar were added, on a scale ranging from -10 (much worse), to +10 (much better). Eighty percent of the respondents expected that balsamic vinegar would make the beer taste worse. The mean rating was -4.03, which is significantly below 0 [F(1,119) = 22.45, p < 0.01]. Expectations, Experience, and Preferences 6 three experiments. The difference between the three conditions was based on the information that respondents received about the beer and the timing of this information (see Figure 3). In the blind condition, respondents tasted the two samples without any information about their contents. In the before condition, respondents were told which beer contained the balsamic vinegar, before tasting either. In the after condition, respondents first tasted the beers as in the blind condition, and were then told (after tasting) which contained the balsamic vinegar. ••• Figure 3 ••• Collectively, these three conditions can test the general effect of top down processes and more importantly, distinguish whether the path by which knowledge influences preferences is the direct or indirect one. A comparison of the blind and before conditions would reveal how disclosure of the secret ingredient affects preferences towards the sample containing it, via either the direct or indirect pathway. If the preference for the MIT brew is lower in the blind relative to the before condition, this would mean that the information about the balsamic vinegar adds positively to the evaluation, and if the preference for the MIT brew is higher in the blind relative to the before condition, this would mean that the information about the balsamic vinegar adds negatively to the evaluation. Since all the three models (see figure 2) predict an influence of knowledge on preferences, a difference between the before and blind conditions would not be informative as to the path by which knowledge influences preferences. If we take the difference between the before and blind conditions as defining the range of possible influence of knowledge on preferences in this case, the relative preference for the MIT brew in the after condition would help us distinguish between the direct and indirect paths. The degree to which preference for the MIT brew is similar in the after and before conditions and different from the blind condition would reveal whether preferences are affected by the direct Expectations, Experience, and Preferences 7 route alone. Similarly, the degree to which preference for the MIT brew is similar in the after and blind conditions and different from the before condition would reveal whether preferences are affected by the indirect route alone (the degree to which consumers’ conceptual aversion influences the gustatory experience itself). In summary, if preferences are driven primarily by the bottom up process, there should be little difference among the three conditions. If the influence of the top down process is via the direct path, preference for the MIT brew should be markedly lower in the before and after conditions compared with the blind condition. If the influence of the top down process is via the indirect path, preference for the MIT brew should be markedly lower in the before condition than the blind and after conditions. Experiments 1-3: Preferences Our