Judging a book by its cover: Prior knowledge determines the effect of embodied cues.

Much as when people try to estimate the probability of an event (“how likely is it that X will happen”) they inadvertently draw on feelings of familiarity (“can I think of a time that X has happened before”), when trying to estimate the importance of something (“how much is this coin worth?”) people may inadvertently draw on feelings of weight (“how heavy does it feel?”). While weight may be correlated with value or importance often enough to make this a reasonable inference (e.g. Piqueras-Fiszman, & Spence 2012), this relationship will extend to situations where physical heft is irrelevant to the question of value or when it emanates from an irrelevant source like weights concealed inside the clipboard holding a questionnaire.

I became interested in the interplay between prior knowledge and physical cues when a student of mine found a perplexing experimental result. He approached students around campus with a copy of the novel The Catcher in the Rye and asked them to rate how influential it was. Half of the people rated a regular hardcover copy, and half rated a copy with metal plates taped inside the cover. Overall, the results were encouraging, but as we examined the data we noticed that the effect seemed to be especially strong among people who had actually read the book, and was virtually absent among people who had not. The opposite of what would intuitively be expected and what would be predicted by heuristic explanations of metaphor effects.  

As it turns out, there are also reasons to predict that knowing more about something may increase the influence of irrelevant cues. If one assumes that physical weight matters because people have a heuristic that “heavy things are important”, knowledge should reduce the effect of weight. However, an alternative theory with a slightly different explanation makes a different prediction. From a semantic priming perspective physical weight matters because the experience makes it more likely that people will bring importance related concepts to mind. Concepts are more like passing thoughts than rules, and like other thoughts they will only influence a judgment  if they seem  applicable to the judgment at hand (Higgins, 1996).

An older study of semantic priming that brought concepts to mind by presenting verbal cues demonstrates this principle well. It found that people evaluated the behavior of a person who enjoyed activities like mountain climbing and kayaking as positive if previously exposed to positive trait words applicable to this context (e.g. “adventurous”), and as negative if previously exposed to negative applicable traits (e.g. “reckless”). However, their evaluations of the person were not influenced by exposure to traits that were not applicable to the person’s description (e.g. “grateful” or “sly”; Higgins, Rholes, & Jones, 1977). Adventurousness has certain connotations that make kayaking seem desirable, while gratitude does not. By a similar logic, a heavier copy of a book may lead one to interpret facts about a book as bearing on its importance, provided that one has relevant facts to be interpreted. For people who know little about the book, a heavy book may still bring importance related concepts to mind, but they are unlikely to be related to the book itself.

Despite this line of reasoning, our initial finding seemed counterintuitive and we were skeptical. However, a reexamination of prior research suggested that contrary to our initial expectations but in agreement with our finding, the existing literature on weight and importance actually seemed to support the idea that knowledge was necessary for physical heft to influence judgments of importance. In the study that investigated the effect of weight on political attitudes (Ackerman et al., 2008), the authors found that while the experience of weight made people supportive of spending money on some issues like economic development, it did not influence support of other issues, like regulating the use of AM radio wave bandwidth, about which they presumably knew little.

A closer examination of the study on weight and currency values revealed a similar pattern (Jostmann et al., 2009). Although people generally estimated coins as more valuable when holding a heavy clipboard, there was considerable variance across currencies, ranging from estimates of the Japanese Yen, which showed a strong effect, to the Ethiopian Birr, which showed no effect. The authors reported that economic importance of countries did not determine whether clipboard weight influenced estimates of value, but a secondary analysis of their data revealed that the impact of the clipboard weight on a currency’s estimated value increased in direct proportion to the number of Google indexed web pages mentioning the country that issued it. In other words, the more familiar the country was to the general public, the greater the effect of weight on estimates of the value of its currency.

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