Hearing acuity and cognition affect older adults’ syntactic processing

Abstract

Cognitive ability is consistently found to alleviate the negative effects of age-related hearing loss (ARHL) on speech comprehension. This study investigated the influence of ARHL and cognition on the processing of reduced relative clauses (RRCs). A sample of older monolingual native English speakers (aged 60-76) was presented acoustic sentences while their electroencephalogram was recorded. The sentences consisted of RRCs and control sentences (CSs), which were almost identical but contained intransitive verbs instead of transitive verbs, which rendered the CSs ungrammatical at the onset of the main clause verb (OMCV). Event-related potentials (ERPs) time-locked to the OMCV were computed. Cluster-based permutation tests showed that ERPs in the P600 time window were significantly more negative in the CS condition than in the RRC condition across participants. It was further investigated whether the P600 effect could be explained by participant-level factors. To this end, mean voltage values for a baseline period and for the P600 time window (500 – 900 ms after OMCV) were extracted and single-trial linear mixed-effects models with random intercepts for participants and items were computed. There were significant interaction effects between condition and hearing thresholds as well as cognition, with higher hearing thresholds, lower working memory, and lower individual alpha frequency being related to smaller or even absent P600 amplitudes. This suggests that hearing- and cognition-dependent differences in speech understanding may at least partly be attributed to differences in syntactical processing.