There is conflicting empirical evidence regarding the role of awareness in second language learning. Possible explanations for the contradictory results include the modality in the exposure and assessment phases of previous experiments. Our study investigated the acquisition of a novel determiner system under incidental exposure conditions and examined the effect of modality in both exposure and assessment phases. Animacy served as a hidden regularity in the determiners, which were embedded in sentences and presented to Chinese speakers of English either in auditory or in visual mode. Learning was assessed by a two-alternative forced-choice test either auditorily or in writing. Implicit and explicit knowledge were measured using retrospective verbal reports and source judgements. Bayesian analysis provided moderate evidence for above chance level learning. Significant learning effects were observed regardless of whether participants based their accuracy judgements on explicit or implicit knowledge. Bayesian analysis showed moderate evidence for above chance learning effects for aware participants. Generalized linear mixed-effects modeling revealed a small-size significant benefit of the auditory exposure modality over the written modality but indicated no significant effect of the modality of assessment or awareness. Our research underscores the importance of considering the role of modality of exposure in incidental second language learning contexts.

In language switching, it is assumed that in order to produce a response in one language, the other language must be inhibited. In unimodal (spoken-spoken) language switching, the fact that the languages share the same primary output channel (the mouth) means that only one language can be produced at a time. In bimodal (spoken-signed) language switching, however, it is possible to produce both languages simultaneously. In our study, we examined modality effects in language switching using multilingual subjects (speaking German, English, and German Sign Language). Focusing on German vocal responses, since they are directly compatible across conditions, we found shorter reaction times, lower error rates, and smaller switch costs in bimodal vs. unimodal switching. This result suggests that there are different inhibitory mechanisms at work in unimodal and bimodal language switching. We propose that lexical inhibition is involved in unimodal switching, whereas output channel inhibition is involved in bimodal switching.