Processing code-blending beyond the lexical level: evidence for a double syntactic derivation?

Bimodal bilinguals master languages in two modalities, spoken and signed, and can use them simultaneously due to the independence of the articulators. This behavior, named code-blending, is one of the hallmarks of bimodal bilingualism. Lexical experiments on production and comprehension in American Sign Language/English showed that blending is not cognitively costly and facilitates lexical access. In this work, we replicated the blending advantage in lexical comprehension for hearing bimodal bilinguals with two other language pairs, French Sign Language (LSF)–French and Italian Sign Language (LIS)–Italian, and we explored whether the facilitation is also found at the sentential level. Results show that blended utterances for languages with incongruent word order like LIS–Italian were processed slower than monolingual utterances, while no difference was found when the word orders were congruent (LSF–French). We discuss these findings in light of linguistic theories of syntactic structure derivation in bimodal bilinguals.