From novel to familiar: Tuning the brain for metaphors

Abstract

Metaphors are fundamental to creative thought and expression. Newly coined metaphors regularly infiltrate our collective vocabulary and gradually become familiar, but how does this shift from novel to conventionalized meaning happen in the brain? We investigated the neural career of metaphors in a functional magnetic resonance imaging study using extensively normed new metaphors and simulated the ordinary, gradual experience of metaphor conventionalization by manipulating participants’ exposure to these metaphors. Results showed that the conventionalization of novel metaphors specifically tunes activity within bilateral inferior prefrontal cortex, left posterior middle temporal gyrus, and right postero-lateral occipital cortex. These results support theoretical accounts attributing a role for the right hemisphere in processing novel, low salience figurative meanings, but also show that conventionalization of metaphoric meaning is a bilaterally-mediated process. Metaphor conventionalization entails a decreased neural load within semantic networks rather than a hemispheric or regional shift across brain areas.

Stimulus needs are a moving target: 240 additional matched literal and metaphorical sentences for testing neural hypotheses about metaphor

“…Rather, motor cortex engagement appears to be modulated by familiarity: Highly conventional figurative uses of verbs, as are found in idioms, do not engage M1/SMA (Aziz-Zadeh, Wilson, Rizzolatti, & Iacoboni, 2006;Raposo, Moss, Stamatakis, & Tyler, 2009), but less familiar metaphoric senses may (Desai et al, 2011;Obert et al, 2014). Similarly, Cardillo et al (2012) observed that pMTG activation was graded by familiarity with action verb metaphors. These studies provide preliminary support for previous hypotheses that the degree of sensorimotor engagement is determined by metaphor novelty, such that sensorimotor areas are more strongly recruited for understanding novel figurative senses of words than for conventional ones (Aziz-Zadeh & Damasio, 2008;Cardillo et al, 2010).…”

“…In partial support of these hypotheses, the emerging picture seems to be that both hemispheres, and especially bilateral prefrontal cortex, are recruited when deriving a new figurative sense. In a novel familiarization task, Cardillo et al (2012) parametrically varied participant experience with novel nominal and predicate metaphors to test for a right-left shift in lateralization with increased familiarity. Instead, their results indicated that the more familiar a metaphor was, the less it engaged a subset of the same regions necessary for comprehending the metaphor for the first time [inferior frontal gyrus (IFG) bilaterally, left posterior middle temporal gyrus (pMTG), and right postero-lateral occipital cortex].…”

Cognitive Neuroscience of Natural Language Use

“…Similarly, Broca's region activation has also been found to go down as participants adapt to novel metaphors (Cardillo, Watson, Schmidt, Kranjec, & Chatterjee, 2012).…”

Emotional context modulates embodied metaphor comprehension

“…Contrary to this is the finding by Raposo et al (2009), who measured the activation of motor and premotor cortices with three action verb conditions. Isolated action verbs (kick) and sentences with literal use of action verbs (kick the ball) activated the premotor cortex, while sentences with idiomatic use of action verbs (kick the bucket) did not (see also Aziz-Zadeh et al (2006) novelty (Cardillo et al, 2012; and context (Schuil et al, 2013). Cardillo et al (2012) directed attention to novelty as a factor through investigating the shift from novel to conventionalized metaphors and how the brain is tuned to this process.…”

“…Isolated action verbs (kick) and sentences with literal use of action verbs (kick the ball) activated the premotor cortex, while sentences with idiomatic use of action verbs (kick the bucket) did not (see also Aziz-Zadeh et al (2006) novelty (Cardillo et al, 2012; and context (Schuil et al, 2013). Cardillo et al (2012) directed attention to novelty as a factor through investigating the shift from novel to conventionalized metaphors and how the brain is tuned to this process. Schuil et al (2013) showed that sentential context modulates the degree to which motor regions are activated.…”