Metaphor aptness and conventionality: A processing fluency account

Conventionality and aptness are two dimensions of metaphorical sentences thought to play an important role in determining how quick and easy it is to process a metaphor. Conventionality refers to the familiarity of a metaphor whereas aptness refers to the degree to which a metaphor vehicle captures important features of a metaphor topic. In recent years it has become clear that operationalizing these two constructs is not as simple as asking naïve raters for subjective judgments. It has been found that ratings of aptness and conventionality are highly correlated, which has led some researchers to pursue alternative methods for measuring the constructs. Here four experiments explored the underlying reasons for the high correlation in ratings of aptness and conventionality and raise doubt about the construct validity of various methods for measuring the two dimensions. Manipulation of the processing fluency of a metaphorical sentence by means of familiarization to similar senses of the metaphor (in vivo conventionalization) was found to influence ratings of the sentence’s aptness. This misattribution may help explain why subjective ratings of aptness and conventionality are highly correlated. Other reasons to question the construct validity of conventionality and aptness measures are observed: For instance, conventionality is shown to be context dependent and thus not attributable to a metaphor vehicle alone, and ratings of aptness reflect salient non-mapping features as well as mapped ones.