Rapp et at.: "Neural correlates of metaphor processing" (2004)

This study used fMRI to investigate which parts of the brain that are involved in the processing of metaphors of the form A is B.

Contrary to expectation, it turned out that all the extra activity that the metaphors induced (compared to the literal control sentences) was in the left hemisphere. A previous PET study had found activation in the right hemisphere, but this may have been due to the more complex syntax they used in their materials.

The authors assert that they used 120 sentences, but they do not include their materials in the paper. This obviously makes the paper much less useful from the point of view of linguistics.

The only two sentences they cite are the following (p. 397):

• Die Worte des Liebhabers sind Harfenklänge (metaphorical)
• Die Worte des Liebhabers sind Lügen (literal)

It's difficult to capture just exactly how poetically tone-deaf this sounds, but think A lover's voice is the sweetest sound, and you're roughly in the right ballpark.

At any rate, we now know that you need to pump slightly more blood to the left-hand side of your brain if I call your lover's words sweet music than if I call them lies. Interpret at your own risk.