The interplay between inhibitory control and metaphor conventionality

When a metaphor is first encountered (lawyers are sharks), several meanings are activated, but the literal ones (lawyers have fins) need to be inhibited to successfully compute the figurative meaning (lawyers are aggressive). With repeated exposure that metaphor becomes conventionalized, and its figurative meaning may be easily accessible without the need to inhibit the corresponding literal meaning. Thus, a central question in the field, and the objective of the current project, relates to how metaphor conventionality and inhibitory control contribute to metaphor comprehension. Participants completed a sense-nonsense task in which they indicated whether metaphorical and literal phrases had sensible meanings. In Experiment 1, participants also completed an inhibitory control task that assessed their ability to inhibit task-irrelevant responses. Participants with lower inhibitory control were slower at responding to more novel metaphors and faster at responding to more conventional metaphors compared with participants with higher inhibitory control. In Experiment 2, we used a dual-task paradigm to reduce participants' inhibitory control resources while performing the sense-nonsense task. Participants completed the sense-nonsense task concurrently with a different secondary task. This assessed their ability to evaluate phrases under low and high inhibitory load conditions. Performance on the sense-nonsense task was higher when processing more conventional than more novel metaphors when participants' inhibitory control processes were taxed in the high load condition. These findings suggest that inhibitory control does play a role in metaphor comprehension-the less conventional a metaphor, the more inhibitory skills are required to compute the figurative meaning.