Impact of motor stroke on novel and conventional action metaphor comprehension

Previous studies indicate that damage to motor brain regions impacts comprehension of literal action-related language. However, whether such damage also impacts comprehension of action-metaphors remains unknown. Such a finding would support the notion that metaphors are grounded in sensorimotor representations. Here we tested this hypothesis by comparing comprehension of novel, conventional, and frozen action and non-action metaphors in 14 right-handed adults with right-sided mild to moderate paresis following left hemisphere motor stroke and 23 neurotypical participants. Consistent with our hypothesis, results indicated that only in the stroke group, accuracy for action metaphors was significantly lower than for non-action metaphors. Further, in the stroke group, accuracy was significantly worse in the following pattern: novel < conventional < frozen action metaphors. These results strongly support the notion that motor-related brain regions are important not only for literal action-related language comprehension, but also for action-related metaphor comprehension, especially for less familiar metaphors.