Individual differences in the distributional learning and overnight consolidation of the Mandarin level-falling tone contrast.

In perceptual studies, musicality and pitch aptitude have been implicated in tone learning, while vocabulary size has been implicated in distributional (segment) learning. Moreover, working memory plays a role in the overnight consolidation of explicit-declarative L2 learning. This study examines how these factors uniquely account for individual differences in the distributional learning and consolidation of an L2 tone contrast, where learners are tonal language speakers, and the training is implicit. Following a previous study investigating distributional tone learning, 66 L1-Cantonese participants who learned and consolidated a Mandarin level-falling tone contrast through distributional exposure were measured in a pitch threshold task, Montreal Battery of Evaluation of Amusia, Mandarin Peabody Picture Vocabulary Test, and an Operation Span task. Pitch threshold predicted immediate learning improvement while working memory predicted overnight consolidation by a bimodal group (not a unimodal group). The findings imply that pitch aptitude may be important in encoding stepwise tonal tokens, and the predictive power of working memory in overnight consolidation extends to implicit tone learning. Meanwhile, musical aptitude may not confer an additional advantage for speakers with native-tone experiences, and learners with a larger L2 vocabulary size might have resisted adaptation to distributional exposure because of robust L2 tonal representations.