RESUMEN
This study investigates heritage bilingual speakers' perception of naturalistic code-switched sentences (i.e., use of both languages in one sentence). Studies of single word perception suggest that code-switching is more difficult to perceive than single language speech. However, such difficulties may not extend to more naturalistic sentences, where predictability and other cues may serve to ameliorate such difficulties. Fifty-four Mexican-American Spanish heritage bilinguals transcribed sentences in noise in English, Spanish, and code-switched blocks. Participants were better at perceiving speech in single language blocks than code-switched blocks. The results indicate that increased language co-activation when perceiving code-switching results in significant processing costs.