Forgetting the Literal: The Role of Inhibition in Metaphor Comprehension

In order for a person to comprehend metaphoric expressions, do metaphor-irrelevant aspects of literal information need to be inhibited? Previous research using sentence-verification paradigms has found that literal associates take longer to process after reading metaphorical sentences; however, it is problematic to infer inhibition from this research. Moreover, previous work has not distinguished between familiar and novel metaphor processing. To test more directly for when inhibition may be required during metaphor processing, we performed 3 experiments using a metaphor-induced lexical forgetting paradigm. Participants initially learned word pairs where the cues were potential metaphoric vehicles and the targets were literal associates (e.g., SHARK-swim). Then, participants read half the vehicles as part of metaphorical sentences, which they interpreted (The lawyer for the defense is a shark). Subsequent forgetting of the literal associates was greater when vehicles had appeared in metaphorical sentences (Experiment 1) and was observed for both familiar and novel metaphors when participants were instructed to interpret the metaphors (Experiment 2) but was observed for only novel metaphors when participants were instructed to simply read the metaphors (Experiment 3). These results suggest that forgetting occurs as a result of inhibitory mechanisms that are engaged to alter activation of irrelevant literal information during metaphor processing, and that these mechanisms are most relevant for the processing demands associated with novel metaphors.