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Comprehension of action metaphors by individuals with Primary Progressive Aphasia: An ERP study in progress
Poster Session E, Sunday, September 14, 11:00 am - 12:30 pm, Field House
This poster is part of the Sandbox Series.
Laura Baiocco1, Vicky T. Lai1, Aneta Kielar1; 1University of Arizona
Primary Progressive Aphasia (PPA) is an atypical variant of Alzheimer’s Disease, characterized by gradual and progressive deterioration of language functions (Mesulam, 2001). In the logopenic variant of PPA (lvPPA) different levels of semantic deficits can be observed alongside word finding impairment (anomia) and impaired verbal working memory. These deficits impact more complex language functions, such as combinatorial processing in sentences. One type of combinatorial process is metaphor, which involves complex association between semantically distant concepts and so far has not been explored in this population. This project aims to investigate whether the semantic deficit in lvPPA extends to metaphorical language. Past event-related potential (ERP) studies in typical younger adults (Lai et al., 2023) showed that metaphoric expressions (e.g., she grasped the idea) elicited more negative N400 than their literal matches (she understood the idea). This N400 effect, when parietally distributed, is typically associated with semantic processing. But when the effect is more frontal, it is associated with concreteness. Studies additionally reported later effects, including late positivity (LP), likely reflecting meaning integration, or late negativity (LN), thought to reflect working memory processes. The behavioral and electrophysiological data will help us to understand the level at which semantic deficit occurs in lvPPA. We hypothesize that if lvPPA process metaphor as a semantic anomaly, we should observe an enhanced parietal N400 effect. However, if individuals with lvPPA show impaired conceptual integration of metaphorical meaning, the N400 effect may be reduced or delayed. Further, in order to specifically discriminate between possible N400 effects due to concreteness (instead of semantic effort), we include a concreteness manipulation. We plan to recruit 20 adults diagnosed with lvPPA and 20 neurotypical controls, all native speakers of English aged 60 to 80. We will use 264 sentences from Lai et al. (2019), which consist of 88 sentences in 3 conditions: (1) metaphorical (The church bent the rules), (2) literal-abstract (The church altered the rules), and (3) literal-concrete (The bodyguard bent the rod). The abstract and concrete verbs were matched in word length and frequency, and conditions were matched for familiarity and predictability. Participants will read sentences word-by-word on a computer screen and respond if they make sense or not. Stimuli will also include 20 semantically anomalous filler sentences for the nonsense behavioral responses (Kielar et al., 2015). We are starting data collection this early May. Behavioral data (accuracy to sensicality judgement task) and ERPs time-locked to the critical verbs will be analyzed in a Mixed Measures ANOVA of 2 (group) x 3 (condition). We expect that our results will clarify 1) the level at which complex conceptual deficit occurs in lvPPA, and 2) whether individuals with lvPPA process metaphors as anomalous or instead show decreased or delayed cross-domain conceptual representation. This study will offer valuable insights into figurative language processing in healthy, neurotypical older adults, and especially in individuals with PPA.
Topic Areas: Disorders: Acquired, Meaning: Discourse and Pragmatics