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Poster C48, Thursday, November 9, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Cognitive Control Mediates Age-Related Reductions in Adaptation to Speaker-Specific Predictability

Shruti Dave1, Trevor Brothers1, Matthew Traxler1, Tamara Swaab1;1University of California, Davis

Resource-based accounts of language processing (Kuperberg & Jaeger, 2016) posit that comprehenders flexibly adjust anticipatory processing in response to the effectiveness of prediction in a given environment. Recent electrophysiological evidence for the resource-based hypothesis has been found in young adults (Brothers et al., 2016), who showed significant differences in N400 effects of prediction as a function of speaker-specific statistics. Dave et al. (2017) further demonstrated that N400 effects of adaption to speaker-specific information were dynamically modulated by individual differences in cognitive control (CC; Stroop and Flanker tasks) and working memory (WM; Listening Span task) resources. Here, we examined whether older adults as a group adapt their predictive processing across different speakers. In addition, we examined whether individual differences on measures of WM and CC influenced sensitivity to speaker-specific statistics in older adult listeners. Recent evidence suggests that older adults do not show specific impairments in predictive relative to contextual processing (Dave et al. [a], under review), but less is known about predictive adaptation to globally available cues. In our experiment, EEG was recorded from 40 young adults (aged 18 to 26) and 40 older adults (aged 61 to 75) while they listened to sentences spoken by two speakers. Half of the sentences were spoken by a reliable speaker, who completed 80% of their sentences with predictable final words (i.e., The dairy cow produced some [milk]) while the other half of the stimuli was spoken by an unreliable speaker (who ended 80% of sentences with plausible but unexpected words, i.e., The dairy cow produced some [noise]). In young adults, larger N400 effects of sentential constraint were found when comprehenders listened to reliable – as compared to unreliable – speakers. However, older adults did not show a significant interaction of speaker reliability and contextual predictability, suggesting that older adults are less sensitive to the global validity of predictive cues. Further, while WM and CC influenced young adults' adjustment of predictive strategies, only CC affected older adults' N400 effects of speaker adaptation. Interestingly, performance on CC measures fully mediated age-related changes in neural effects of speaker adaptation. Our results are in line with previous research (Dave et al. [b], under review; Federmeier et al., 2002) suggesting that generalized age-related declines in WM capacity weaken relations between WM and predictive processing. Importantly, these data also contribute that age-related reductions in CC explain age-related declines in adaptation of predictive processing in response to environmental cues.

Topic Area: Meaning: Discourse and Pragmatics

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