ERP Evidence of Working Memory Capacity and Signal-to-Noise Ratio Effects on Sentence Plausibility Tasks in Elderly Adults

Abstract

Objectives: The purpose of this study is to evaluate the effect of Signal to Noise Ratio (SNR) and working memory capacity on the auditory processing of the elderly by comparing the average amplitude of event-related potentials (ERP) between groups in the sentence plausibility judgment task under the control of SNR.Methods: A total of 26 elderly people participated in this study, and based on the results of the working memory test, were divided into high a working memory (high WM) group (N= 13) and a low working memory (low WM) group (N= 13). The sentence stimuli consisted of plausible and implausible sentences. Implausible sentences were manipulated to cause a semantic violation in the verb. A white noise was added to the portion of the predicate to be –5 dB, 0 dB, and 5 dB SNR in the recorded sentence.Results: In the behavioral analysis, differences between the SNRs were significant. –5 dB SNR conditions revealed inactive performance, confirming that noise is a variable that increases cognitive load and difficulty in auditory processing. In the ERP analysis, the mean amplitude of the high WM group was significantly greater than the low WM group, and a distinct difference in N400 components between the groups was also observed in the grand average waveform graph.Conclusion: Intergroup differences were more evident in the conditions of SNR, which requires more listening effort. However, this may show that the low WM group had an inferior ability to detect the cognition of semantic implausibility in real time compared to the high WM group.