The Roles of Aptness, Conventionality, and Working Memory in the Production of Metaphors and Similes

What factors affect the processes by which vehicles are selected for metaphors and similes? What determines the form of figurative statement people prefer to use? To answer these questions we contrast the predictions of class-inclusion theory and the structure mapping theory and its career of metaphor variant with respect to aptness, conventionality, and working memory (WM) in a figurative statement production task. Consistent with both theories we found that property-aptness influences the time required to generate a vehicle, that conventionality predicts the quality of vehicles and the time it takes to generate them, and that WM capacity predicts the quality of vehicles produced. However, it was class-inclusion theory that best explained why we observed no effect of aptness on vehicle quality and why WM and vehicle quality, but not conventionality, influenced the likelihood of using the metaphor or simile form. We end with a discussion of how these results relate to Kintsch's Predication Model of comprehension and how the model may be extended to account for behavior in figurative statement production.