The identification of trained nonnative speech sounds improve after a daytime nap

Abstract

Perceptual ability of nonnative speech sounds improves in the 24 hours that follow learning, in the absence of further training (Earle and Myers, 2015a, 2015b). These improvements are particularly salient in the morning, that is, immediately following the overnight between-session interval. These observations are moreover associated with rudimentary measures of sleep duration (Earle et al., 2017). While we have attributed these perceptual gains to memory consolidation during sleep (Marshall and Born, 2007), there yet remains the possibility that consolidation of acoustic information occurs during a relative period of absence of interfering auditory input that is related to time spent in sleep. In this study, we trained a group of college students in the identification of the Hindi dental-retroflex contrast at noon, and then recorded their electroencephalographic (EEG) activity during an in-lab nap immediately following training. We measured perceptual performance on the trained nonnative contrast immediately before and after a daytime nap. Data from a preliminary sample of 8 participants demonstrate a trending association between changes in perceptual behavior and the number of sleep spindles observed during stage N2 post-training sleep. This association may indicate the role of sleep, and hippocampal memory consolidation, in the formation of speech sound representations.Perceptual ability of nonnative speech sounds improves in the 24 hours that follow learning, in the absence of further training (Earle and Myers, 2015a, 2015b). These improvements are particularly salient in the morning, that is, immediately following the overnight between-session interval. These observations are moreover associated with rudimentary measures of sleep duration (Earle et al., 2017). While we have attributed these perceptual gains to memory consolidation during sleep (Marshall and Born, 2007), there yet remains the possibility that consolidation of acoustic information occurs during a relative period of absence of interfering auditory input that is related to time spent in sleep. In this study, we trained a group of college students in the identification of the Hindi dental-retroflex contrast at noon, and then recorded their electroencephalographic (EEG) activity during an in-lab nap immediately following training. We measured perceptual performance on the trained nonnative contrast immediat...