Interpretive Diversity as a Source of Metaphor-Simile Distinction

Interpretive Diversity as a Source of Metaphor-Simile Distinction Akira Utsumi (utsumi@se.uec.ac.jp) Yuu Kuwabara (kuwabara@utm.se.uec.ac.jp) Department of Systems Engineering, The University of Electro-Communications 1-5-1 Chofugaoka, Chofushi, Tokyo 182-8585, Japan Abstract In this paper, we argue that the metaphor form of a compari- son (i.e., a topic-vehicle pair) is preferred over, and more com- prehensible than, the simile form when the interpretive diver- sity for that comparison is high. Interpretive diversity refers to the richness of the figurative meaning of a comparison; it is high to the extent that more features or properties are re- lated to the figurative meaning and their values of salience are more uniformly distributed. We tested this claim through three experiments. Experiment 1 examined preference for the metaphor form and found that, as the interpretive diversity of the features shared by the topic and the vehicle increased, the metaphor preference increased as well. Furthermore, inter- pretive diversity was found to have a greater effect on meta- phor preference than topic-vehicle similarity, which Chiappe and Kennedy (2001) claimed was a source of metaphor prefer- ence. Experiment 2 assessed familiarity of topic-vehicle pairs and demonstrated that interpretive diversity was more impor- tant in determining the metaphor preference of less familiar pairs than that of familiar pairs. Experiment 3 addressed com- prehension of metaphors and similes and found that metaphors were comprehended more easily than similes when the inter- pretive diversity of the figurative meaning is high. These find- ings provide empirical evidence in favor of our argument and suggest that metaphor-simile distinction is better explained by interpretive diversity. Introduction When we describe a concept (i.e., topic) figuratively in terms of a different concept (i.e., vehicle), we can express the com- parison in two ways: in metaphor form (X is Y) and in simile form (X is like Y). Since metaphor and simile express almost the same figurative meaning, it is often said that a metaphor is an indirect paraphrase of a simile. If so, however, why do we use both expressions without bringing them together? Recently some experimental studies have tackled the prob- lem of how metaphor and simile differ. One series of exper- imental studies (Chiappe and Kennedy 1999, 2001; Chiappe, Kennedy, and Chiappe 2003) has been made on what proper- ties affect people’s preference for the metaphor form. These studies demonstrated that metaphor preference was explained by similarity between a topic and a vehicle, or aptness of the comparison. The metaphor form was preferred over the sim- ile form when the topic and the vehicle of the comparison were highly similar or when the comparison was highly apt, while the simile form was preferred when the topic-vehicle similarity or the aptness of comparison was low. Another se- ries of experimental studies (Bowdle and Gentner 1999; Gen- tner and Bowdle 2001; Zharikov and Gentner 2002) has ad- dressed the conventionality of the figurative meaning of the vehicle (i.e., the base term) as a source for metaphor-simile distinction. These studies demonstrated that the simile form was preferred when the vehicle of the comparison was novel, but the metaphor form became preferred when that vehicle was conventionalized by repeated figurative use. In this paper, we propose interpretive diversity of a com- parison as a key property which explains the metaphor-simile distinction. By the term ‘interpretive diversity’, we mean the richness of the figurative meaning of a comparison. The rich- ness of the figurative meaning depends on two factors, that is, the number of features (or predicates) involved in the mean- ing and the salience distribution of those features (Utsumi 2005). In general, the richness of a comparison is high to the extent that more features are related to the figurative meaning and that the values of salience of those features are more uni- formly distributed. For example, the comparison “Deserts are (like) ovens” may possibly convey one highly salient meaning of “They are burning hot” with a relatively much less salient meanings such as “They are dry” or “Their temperature is greatly changed”. Such interpretation can be seen as less rich or less diverse. On the other hand, the comparison “History is (like) footprints” can be considered as having a highly rich, diverse interpretation because many equally salient meanings such as “It remains behind”, “It is a thing of the past” and “It is a living proof” are contained in the figurative interpretation. Interpretive diversity can be assessed by using an idea of Shannon’s entropy H(X) defined by the following equation. H(X) = − p(x) log 2 p(x) x∈X A higher value of entropy means that a single random vari- able X has more states and their probability p(x) is more uni- formly distributed. The entropy is maximal, H(X) = log 2 N with N the number of states in X, when all states have the same probability 1/N , and the entropy is minimal, H(X) = 0, when one state has probability 1 and all others have prob- ability 0. Therefore, if we regard the salience distribution of features for the figurative interpretation of a comparison as a probability distribution p(x), the entropy becomes a reason- able measure of richness of that interpretation. We then argue that, when the interpretive diversity for a comparison is high, i.e., when the figurative meaning is highly diverse, the metaphor form of that comparison is pre- ferred over, and more comprehensible than, the simile form. According to our argument, for example, “History is foot- prints” may be preferred over and comprehended more eas- ily than “History is like footprints” because the comparison