| Summary: | 碩士 === 國立臺灣大學 === 語言學研究所 === 104 === Whether aging affects comprehension of metaphors has not been systematically investigated. This study assessed event-related potentials (ERPs) from 24 healthy older adults while they read literal, familiar metaphorical, and unfamiliar metaphorical usages of sentence-final action verbs, and judged, 800ms post verb onset, if a probe that was either literally related or unrelated to the verb was related to the sentential message. Unlike younger adults in the literature that showed a larger N400 response followed by a late positive component (LPC) to unfamiliar metaphors relative to the literal condition, older adults as a group showed a negativity to unfamiliar metaphors only in a later and more restricted time window (450-550ms) and no LPC effect. Further analysis suggested that individual variations of older adults’ brain responses could be accounted for by their verbal fluency scores. Older adults with higher verbal fluency elicited a sustained negativity to unfamiliar metaphors relative to the literal condition (450-750ms). However, older adults with lower verbal fluency scores did not show any reliable effects in their brain responses. Despite these differences in online measures, older adults in general were quite accurate (99.05% in familiar metaphors and 94.32% in unfamiliar metaphors) in a subsequent offline metaphor-paraphrasing task, indicating that, given time, older adults could successfully obtain the figurative readings for metaphors. These results suggest that metaphor familiarity modulates older adults’ online processing of metaphors in that age-related differences are mainly significant in unfamiliar metaphors. Older adults in general elicit smaller and later N400 effect and no LPC relative to younger adults in literature. In addition, individual cognitive differences affect older adults’ online processing of metaphors, with high-functioning older adults elicit a prolonged negativity in unfamiliar metaphors, suggesting higher functioning older adults are better able to recruit additional cognitive-neural resources to aid unfamiliar metaphor interpretations.
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