Sleep Facilitates Generalisation of Accent Adaptation to a New Talker.

Lexically-guided phonetic retuning helps listeners adapt to the phonetic "fingerprint" of a talker. Previous findings show that listeners can generalise from one accented talker to another accented talker, but only for phonetically similar talkers. We tested whether sleep-mediated consolidation promotes generalisation across accented talkers who are not phonetically similar. Native-English participants were trained on a Mandarin-accented talker and tested on this talker and an untrained Mandarin talker. Experiment 1 showed adaptation for the trained talker and a weak transfer to the untrained talker. In Experiment 2, participants were trained and tested either in the morning (Same-Day group) or evening (Overnight group), and again after twelve hours. Both groups retained talker-specific learning over the 12-hour delay. Importantly, the Overnight group showed improvements for the untrained talker, whereas the Same-Day group's performance on the untrained talker deteriorated. We suggest that sleep facilitated talker generalisation by helping listeners abstract away from specific acoustic properties of the trained talker.