The effect of sleep on learned sensitivity to a non-native phonetic contrast
Sayako Earle, Emily B. Myers · The Journal of the Acoustical Society of America · 2013
Consolidation during sleep is thought to play a role in integrating newly learned words into the preexisting lexicon (e.g., Dumay and Gaskell, 2007), while the effect is in stabilizing degraded information against decay when learning to map synthesized speech onto native phonology (Fenn, Nusbaum, Margoliash, 2003). In the current study, we investigated the effects of overnight consolidation on discrimination between new (nonnative) phonetic categories. Fifty-four monolingual English speakers were trained to categorize tokens from a non-native dental-retroflex contrast. Half of the participants were trained in the evening, and the other half were trained in the morning. Discrimination ability was tested 8-14 h post-training and 22-26 h post-training in order that the effects of intervening sleep (evening group) or daytime activity (morning group) could be assessed. Discrimination in the trained vowel context improved after the overnight between-session interval in the night group, but declined slightly in the morning group. Both training groups improved in discrimination ability for an untrained vowel context immediately following the overnight between-session interval, but not before. Results suggest that memory consolidation during sleep, proactive interference during native language exposure, or both play a role in non-native phonetic learning.