This study examined whether musical training, ethnicity, and experience with a natural tone language influenced sensitivity to tone while listening to an artificial tone language. The language was designed with three tones, modeled after level-tone African languages. Participants listened to a 15-min random concatenation of six 3-syllable words. Sensitivity to tone was assessed using minimal pairs differing only in one syllable (nonword task: e.g., to-kà-su compared to ca-fí-to) or only in tone (tone task: e.g., to-kà-su compared to to-ká-su). Proficiency in an East Asian heritage language was the strongest predictor of success on the tone task. Asians without tone language experience were no better than other ethnic groups. We conclude by considering implications for research on second language learning, especially as approached through artificial language learning.

Previous studies of semantic implicit learning in language have only examined learning grammatical form-meaning connections in which learning could have been supported by prior linguistic knowledge. In this study we target the domain of verb meaning, specifically semantic preferences regarding novel verbs (e.g., the preference for a novel verb to take abstract objects). Using a reaction time methodology we show that, after exposure to correct verb-noun combinations, reaction times to incorrect combinations are slowed down even for participants who are unaware of the semantic regularity. This effect was obtained on a decision that was irrelevant to the actual underlying regularity, suggesting that the knowledge that has been acquired exerts its influence automatically, hence satisfying one criterion for implicitness. Combined with a lack of verbalizable knowledge, these experiments provide strong evidence for semantic implicit learning in language.

The current study aims to make an initial neuroimaging contribution to central implicit-explicit issues in second language (L2) acquisition by considering how implicit and explicit contexts mediate the neural representation of L2. Focusing on implicit contexts, the study employs a longitudinal design to examine the neural representation of L2 syntax and also considers how the neural circuits underlying L2 syntax vary among learners who exhibit different levels of performance on linguistic and cognitive tasks. Results suggest that when exposed to a L2 under an implicit context, some learners are able to quickly rely on neural circuits associated with first language grammar and procedural memory, whereas other learners increasingly use extralinguistic neural circuits related to control mechanisms to process syntax. Thus, there may be multiple ways in which L2 is represented neurally, at least when learned under implicit contexts.