Slide Slam Q16
Where in the brain is “pragmatics”? The case of verbal metaphors in aphasia
Laura Pissani1, Caitlyn Antal1, Kyan Salehi1, Alexa Ray Falcone1, Roberto G. de Almeida1; 1Concordia University
INTRODUCTION The comprehension of sentences such as “The professor devoured the paper” requires generating inferences on the relation between the subject (professor) and the object (paper) beyond what the verb (devour) means literally. Thus, metaphor comprehension might rely on an early parsing that is based on linguistic (viz., syntactic-semantic) predicate-argument relations, which are then further interpreted through non-linguistic (viz., pragmatic) inferential processes. Much research has focused on examining the contribution of the right and left hemispheres in linguistic and non-linguistic aspects of language comprehension. Early studies have reported that patients with right hemisphere damage (RHD) have difficulties when drawing inferences from sentences or discourse (Beeman, 1993; Brownell et al., 1986), suggesting that the RH is crucial for processing pragmatic information, including metaphors (Winner & Gardner, 1977) and connotative aspects of lexical meaning (Brownell et al., 1984). However, more recent studies have reported conflicting results, wherein patients with either left hemisphere damage (LHD; e.g., Cieślicka, Rataj, & Jaworska, 2011) or RHD (Ianni et al., 2014) show difficulties with metaphor comprehension when compared to healthy controls. Our primary goal was to investigate how RHD and LHD patients, with different etiologies, interpreted sentences containing verbal metaphors in contrast with other sentences. METHOD Participants included 4 fluent [FL], 5 non-fluent [NF], 3 mixed but predominantly non-fluent [MN], 2 with mixed aphasia [MX], and 41 healthy controls. In each trial, participants were aurally presented with a sentence, which was immediately followed by two pictures on a computer screen. Their task was to choose the picture that best represented the sentence they heard. We contrasted four different types of sentences: (a) metaphorical (The professor devoured the paper), (b) literal (The professor read the paper), (c) indeterminate (The professor began the paper), and (d) determinate (The professor marked the paper). Given that indeterminate sentences are also said to rely on pragmatic enrichment (de Almeida, 2018), they were treated as pragmatic controls for metaphorical sentences. Only one of the pictures was the correct choice for the metaphorical and literal sentences, whereas the second picture was the correct choice for the indeterminate and determinate sentences. RESULTS Repeated-measures ANOVAs showed that, when compared to healthy controls, FL and MX had significantly more difficulty choosing the correct picture when presented with metaphorical sentences. Moreover, we found an effect of hemisphere, whereby individuals with LHD performed significantly worse than controls only with metaphorical sentences. Interestingly, the opposite pattern was found for individuals with RHD. Namely, individuals with RHD had significantly more difficulty choosing the correct picture in comparison to controls, only when presented with indeterminate sentences. Case-series analyses will be presented. DISCUSSION Our analyses suggest that the comprehension of metaphorical sentences may predominantly rely on the recruitment of semantic and pragmatic processes in the LH. We also found that the comprehension of indeterminate sentences —which arguably also rely on pragmatic enrichment—was significantly more impaired in individuals with RHD. Given this dissociation pattern, our results suggest that the interpretation of metaphorical and indeterminate sentences may rely on different underlying pragmatic processes.