Linking frequency to bilingual switch costs during real-time sentence comprehension

Bilinguals experience processing costs when comprehending code-switches, yet the magnitude of the cost fluctuates depending on numerous factors. We tested whether switch costs vary based on the frequency of different types of code-switches, as estimated from natural corpora of bilingual speech and text. Spanish-English bilinguals in the U.S. read single-language and code-switched sentences in a self-paced task. Sentence regions containing code-switches were read more slowly than single-language control regions, consistent with the idea that integrating a code-switch poses a processing challenge. Crucially, more frequent code-switches elicited significantly smaller costs both within and across most classes of switch types (e.g., within verb phrases and when comparing switches at verb-phrase and noun-phrase sites). The results suggest that, in addition to learning distributions of syntactic and semantic patterns, bilinguals develop finely tuned expectations about code-switching behavior - representing one reason why code-switching in naturalistic contexts may not be particularly costly.