Over 20% of the US population speaks a language other than English at home and bilingualism has long been the norm outside the US. The value of knowing more than one language is becoming increasingly relevant as technology develops and US industry connects with individuals all over the world, even with just a handheld device. People who speak multiple languages have greater potential to connect with a broader audience or customer base. At the same time, research has demonstrated that knowledge of more than one language can change some aspects of native language use: the burden associated with bilingualism can lead to subtle but significant disadvantages in some aspects of cognitive performance (e.g., vocabulary), but to significant advantages in other aspects (e.g., resolving conflict, sustained focus of attention). Such differences have potentially serious implications in many settings, including educational and medical settings. For example, how should bilingual children best be served in school settings to enable them to learn English quickly while maintaining knowledge of their Heritage Language spoken in the home? What methods are best to pursue when attempting to identify learning disabilities in bilingual children? At the other end of the lifespan, in aging bilinguals, what is the best method for identifying current or possibly imminent cognitive decline?
The proposed studies will investigate the consequences of bilingualism for language and cognitive processing by comparing bilinguals with monolinguals in a series of behavioral experiments designed to test how bilinguals choose which language they intend to speak and how this process is more generally related to choice behaviors. Bilinguals will read aloud sentences that mix languages, will be asked to switch between languages or between other (non-linguistic) tasks, name pictures in both languages, or translate between languages. Relationships among these tasks will be examined. A driving hypothesis underlying the current work is that 1) bilinguals maintain control over which language they speak at least in part by relying on cognitive abilities not related to language and 2) bilingual language use can improve general abilities related to rapid switching, monitoring, and resolving conflict between response alternatives (e.g., needing to avoid distraction). This hypothesis will be tested by examining how performance changes when more than one language must be controlled and whether training with language switching improves general cognitive abilities and vice versa (e.g., if managing response competition transfers across non-linguistic and linguistic tasks). These studies will clarify the relationship between bilingualism and cognitive test performance and establish conditions that minimize possible costs and maximize potential benefits of bilingualism. The proposed studies will develop theoretical models of cognitive control and bilingual language processing, which will lay the groundwork necessary to develop theory-driven approaches to assessment and treatment of cognitive and linguistic abilities of young and aging monolinguals and bilinguals alike.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
