Comparison and Choice 1 Running Head : COMPARISON AND CHOICE Structural Comparison and Consumer Choice

Psychological research has demonstrated important parallels between the structural alignment process involved in judgments of similarity and the processes that are involved in analogical reasoning. Gradually, this work on comparisons was applied to consumer choice. In this paper, we review the influence of structural alignment on choices among a set of options. Then, we discuss extensions of this work to comparative advertising and to the role of analogy in marketing communication. Finally, we discuss important extensions to structural alignment suggested by this work such as the key role that affect plays in comparisons made during the choice process. Comparison and Choice 3 It is a truism to say that consumers buy a product because they prefer it. The question is why consumers exhibit the preferences they do. The assumption that people have fixed, well-articulated preferences does not accurately predict people’s decision making (e.g., Russo, Medvec & Meloy, 1996; Simon, Krawczyk & Holyoak, 1999)— people’s preferences are not fixed but relative (Kahneman & Tversky, 1979). In order for preferences to be relative, there must be some implicit or explicit comparison among items. A pioneering business writer, Mary Parker Follet, made a compelling case in the 1920s that people construct preferences by drawing comparisons (Follet, 1995, p. 75): “we do not stop to examine a desire until another is disputing right of way with it. Revaluation is the flower of comparison. ” There is now consensus that people’s ability to make comparisons plays a crucial role in the processes they use to make choices (e.g., Medin, Goldstone, & Markman, 1995; Payne, Bettman, & Johnson, 1993). Over the past 30 years, there has been significant theoretical and empirical development in our understanding of the way that comparisons are processed. As a result, we now have a greater ability to predict consumers’ choices. Supporting the idea that comparison is closely involved in choice, research has found that comparisons play a role in many aspects of consumer behavior. Most obviously, consumers compare options when deciding among multiple available products of the same type (e.g., Houston, Sherman, & Baker, 1989) (Hsee, 1996). Consumers also process comparisons presented in advertisements. Some advertisements invoke comparison because they contrast products (Snyder, 1992). Other advertisements invoke comparison as a means to explain new products, taking advantage of analogies to known products (e.g., J Gregan-Paxton & Roedder John, 1997). Still, in much of the research on consumer behavior and choice more generally, the nature of the comparison process is not specified. Instead, predictions for the influence of comparison on consumer choice are drawn from general principles. In this paper, we start by summarizing a more specific theory of comparison—the structural alignment model (Gentner & Markman, 1997). Then, we review research on comparison among options, comparative advertising, and analogy in product communication. We demonstrate that much of this work is compatible with the structural alignment model, and that there is value to its more precise predictions. Finally, we discuss ways to address more specific questions about consumer behavior by embedding research within a specific model of comparison. Structural alignment and comparison Any theory of comparison has to make assumptions about how people represent information, and has to specify a process for relating pairs of representations to assess their commonalities and differences (Markman, 1999). A classic early model of comparison was Tversky’s (1977) contrast model. Because this model is an important precursor to the structural alignment model (and figures prominently in research on choice), we discuss it in some detail. This model assumed that people represent objects (such as the options in a choice setting) as sets of features, with each feature describing one property of an object. The contrast model then specifies that the comparison process is a matter of performing elementary set operations on the sets of features. The intersection of two feature sets is the set of commonalities between the items. The set differences are the distinctive features between the two items. The contrast model predicts that the similarity of two objects increases as the number of commonalities Comparison and Choice 4 increases and as the number of distinctive features decreases. For cognitive processes that require attending to the commonalities and differences, the content of the sets of common and distinctive features can be used for further processing. The structural alignment model of comparison began as a model of analogical reasoning and was gradually extended to more mundane comparisons (Gentner, 1983; Gentner & Markman, 1997). Initially, the model was designed to explain how people make analogical comparisons and how they transfer information from one domain of knowledge to another. The structural alignment model makes different claims than the contrast model about how people represent knowledge and about how the comparison process works. According to structural alignment, objects are represented using structured hierarchical representations like the ones in Figure 1. These representations consist of entities, which are the basic components of the representation. In the top part of Figure 1, the camera, scene, and computer are entities. Entities are described by properties called attributes. In this example, the camera is described by the attribute “lightweight. ” Obviously, most entities are described by a large number of attributes. Critically, representations also contain explicit relations between elements that specify the ways that two or more entities, or other relations, are linked to each other. The items linked by a relation are called arguments. For example, by convention, we would write the left-most relation in top art of Figure 1 as capture(camera, scene), where “camera” is the first argument of the relation “capture. ” Generically, we can use variables to denote the arguments, writing this relation as capture(x,y). Relations are particularly important for representing information about causal and functional knowledge. In analogy, relations are central. Pairs that are analogous share a common set of relations, even though those relations apply to different arguments. This makes the pairs dissimilar on the surface. For example, a digital camera and a scanner do not look alike. They are not used for the same purposes most of the time. However, they play analogous roles. Both devices capture images that can be transferred to a computer and processed later. The ability to represent and find commonalities on the basis of relations lies at the heart of structural alignment. There are a number of computational accounts that specify algorithms that compare pairs of relational structures (e.g., Falkenhainer, Forbus, & Gentner, 1989; Hummel & Holyoak, 1997). The details of these processes are not crucial for the present discussion, but some general properties of this process are important (Gentner, 1983). First, comparisons are asymmetric. There is a base domain that is typically the one you know most about, and a target domain, which is one that you seek to learn about by analogy. When knowledge of one domain is extended based on knowledge of the other domain, these inferences are drawn from the base to the target. According to structural alignment, the comparison process highlights the relations common to the representations of each object. When common relations are found, the process aims to match the arguments to those relations as well. For example, in the comparison of the scanner and the digital camera (shown in Figure 1), matching the “capture(x,y)” relations in each representation leads the “scene” in the top to be matched to the “document” in the bottom, because both are the second arguments to the “capture” relation. Thus, even though the scene and the document do not look the same, they play the same role in each situation, and so they correspond. Comparison and Choice 5 The structural alignment model’s comparison process also supports finding the commonalities and differences of pairs of objects. The commonalities are straightforward. The elements of the two representations that correspond are the commonalities. The detection of commonalities can also lead to the detection of differences. For example, matching the “capture(x,y)” relation in the two domains in Figure 1 leads to the recognition that cameras capture scenes, while scanners capture documents. Scenes and documents are noticed as a difference, because they each play the same role within their respective representations. That is, they are noticed as differences because of the commonalities observed. These differences that are rooted in the similarities of a pair are called alignable differences (Gentner & Markman, 1997; Markman & Gentner, 1993). Alignable differences are contrasted with nonalignable differences, which are elements in one representation that have no correspondence in the other representation. For example, the top representation has the relation “process(computer, data),” which has no equivalent relation in the bottom representation. Thus, this representational element is a nonalignable difference. Much research on the comparison process suggests that commonalities and alignable differences are more important outputs of comparisons than are nonalignable differences. For example, commonalities and alignable differences get more weight in judgments of similarity than do nonalignable differences (Markman & Gentner, 1993, 1996). People also find alignable differences easier to list than nonalignable differences (Gentner & Gunn, 2001; Gentner & Markman, 1994). Analogies are also powerful, because they allow knowledge from one domain to be carried over to a second domain through a process called analogical