The present study provides insight into cross-language activation in hearing bimodal bilinguals by (1) examining co-activation of spoken words during processing of signs by hearing bimodal bilingual users of Dutch (their L1) and Sign Language of the Netherlands (NGT; late learners) and (2) investigating the contribution of mouthings to bimodal cross-language activation. NGT signs were presented with or without mouthings in two sign-picture verification experiments. In both experiments the phonological relation (unrelated, cohort overlap or final rhyme overlap) between the Dutch translation equivalents of the NGT signs and pictures was manipulated. Across both experiments, the results showed slower responses for sign-picture pairs with final rhyme overlap relative to phonologically unrelated sign-picture pairs, indicating co-activation of the spoken language during sign processing, but no significant effect for sign-picture pairs with cohort overlap in Dutch. In addition, co-activation was not affected by the presence or absence of mouthings.

Mouthings, the spoken language elements in sign language discourse, are typically analysed as having a redundant, one-on-one relationship with manual signs, both semantically and temporally. We explore exceptions to this presupposed semantic and temporal congruency in a corpus of spontaneous signed conversation by deaf users of Sign Language of the Netherlands (NGT). We identify specifying mouthings (words with a different meaning than the co-occurring sign), solo mouthings (uttered while the hands are inactive) and added mouthings (words added to a signing stream without their corresponding sign), and make a sentence-level analysis of their occurrences. These non-redundant mouthings occurred in 12% of all utterances, and were made by almost all signers. We argue for the presence of a code-blending continuum for NGT, where NGT is the matrix language and spoken Dutch is blended in, in various degrees. We suggest expansion of existing code-mixing models, to allow for description of bimodal mixing.