Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Janet L. McDonald


The primary objective of this dissertation was to empirically test the implications of the code-switching hypothesis (Peal & Lambert, 1962) for nonlinguistic cognitive abilities in bilingual adults. It was hypothesized that bilinguals, by virtue of their ability to switching between two linguistic systems, may enjoy cognitive advantages in the nonlinguistic domain for tasks that require abilities related to language switching. It was postulated that the underlying mechanisms of code switching are the bilingual's abilities to inhibit the processing of irrelevant information and activate previously suppressed information. To determine if a bilingual advantage exists for these abilities, bilingual and monolingual adults performed three nonlinguistic tasks designed to measure nonlinguistic task-switching, suppression of irrelevant information, and activation of previously suppressed information. While no differences in performance were observed between the linguistic groups on these tasks, methodological problems with two of the tasks prohibited a conclusive determination about the existence of bilingual advantages. A second objective of this dissertation was to examine bilingual adults' language switching abilities and determine if there is a relationship between switch costs in the nonlinguistic and linguistic domains. Bilingual adults performed a language switching task and it was found that linguistic switch costs were positively correlated with nonlinguistic switch costs. The implications of this relationship are discussed in terms of the underlying mechanisms that are utilized for linguistic and nonlinguistic switching. Future directions for exploring bilingual advantages for cognitive processing and elucidating the relationship between nonlinguistic and linguistic switching abilities in adults are discussed.