The contributions of proficiency and semantics to the bilingual sentence superiority effect

A long-standing question about bilingualism concerns which representations are shared across languages. Recent work has revealed a bilingual Sentence Superiority Effect (SSE) among French-English bilinguals reading mixed-language sentences: identification of target words is more accurate in syntactically grammatical than ungrammatical sentences. While this ability to connect words across the two languages has been attributed to a rapid parsing of shared syntactic representations, outstanding questions remain about the role of semantics. Here, we replicate the SSE in Spanish-English bilinguals (e.g., better identification of vacío in "my vaso is vacío" [my glass is empty] than "is vaso my vacío" [is glass my empty]). Importantly, we report evidence that semantics do contribute to word identification, but significantly less than syntax and only in the context of syntactically grammatical sentences. Moreover, the effect is moderated by language proficiency, further constraining the conditions under which shared cross-linguistic representations are rapidly accessed in the bilingual mind.