The Effects of Working Memory Capacity in Metaphor and Metonymy Comprehension in Mandarin-English Bilinguals’ Minds: An fMRI Study

Abstract

This study investigated the role of working memory capacity (WMC) in metaphoric and metonymic processing in Mandarin–English bilinguals’ minds. It also explored the neural correlations between metaphor and metonymy computations. We adopted event-related functional magnetic resonance imaging (fMRI) design, which consisted of 21 English dialogic sets of stimuli and created five conditions: systematic literal, circumstantial literal, metaphor, systematic metonymy, and circumstantial metonymy, contextualizing in daily conversations. A similar fronto-temporal network for the figurative language processing pattern was found: superior temporal gyrus (STG) for metaphorical comprehension and inferior parietal junction (IPJ) for metonymic processing. Consistent brain regions were identified in previous studies, in the homologue Right Hemisphere, in better WMC bilinguals. The degree to which bilateral strategies that bilinguals with better WMC or larger vocabulary size resort to is differently modulated by subtypes of metonymies. In particular, when processing circumstantial metonymy, cuneus (where putamen is contained) was activated as higher span bilinguals filtered out irrelevant information, resorting to inhibitory control use. Cingulate gyrus activation was also revealed in better WMC bilinguals, reflecting their mental flexibility to adopt the subjective perspective of critical figurative items by self-control. It is hoped that this research provides a better understanding of Mandarin–English bilinguals’ English metaphoric and metonymic processing in Taiwan.