Blog post written by Sara Incera and Conor T. McLennan based on an article in the journal Bilingualism: Language and Cognition
We analyzed how participants moved a computer mouse in order to compare the performance of bilinguals and monolinguals in a Stroop task. Participants were instructed to respond to the color of the words by clicking on response options on the screen. For example, if the word blue appeared in the center of the screen and was presented in the color yellow, he or she was supposed to click on the response option containing yellow, which appeared in one of the top corners of the screen, and not on the response option containing blue, which appeared in the opposite corner. The ability to inhibit the blue response in this example is one measure of executive control. The bilingual advantage hypothesis states that lifelong bilingualism enhances executive control (e.g., Bialystok, 1999). Nevertheless, there is a debate in the literature regarding these effects. A number of studies have reported null effects of bilingualism across different executive control tasks (e.g., De Bruin, Traccani, & Della Sala, 2014).
We recorded when participants started moving the mouse (initiation times), and how fast they moved toward the correct response (x-coordinates over time). We compared two bilingual groups and one monolingual group. There were two bilingual groups to measure how different levels of conflict monitoring (having both or one language active) influences performance. Initiation times were longer for bilinguals than monolinguals; however, bilinguals moved faster toward the correct response. Taken together, these results indicate that bilinguals behave qualitatively differently from monolinguals; bilinguals are “experts” at managing conflicting information. Experts across many different domains take longer to initiate a response, but then outperform novices. These qualitative differences in performance could be at the root of apparently contradictory findings in the bilingual literature. The bilingual expertise hypothesis may be one way to account for these conflicting results.
In conclusion, bilinguals performed differently (started later but then moved faster toward the correct response) than monolinguals. These effects were maximized in the incongruent condition and in the bilingual group that had both languages active. One possible explanation for the conflicting findings in the literature related to the bilingual advantage is that bilinguals have a qualitatively different processing style that can elude detection by traditional reaction time measures. Bilinguals wait longer to initiate a response and then respond faster; therefore, an advantage would only be detected using reaction time measures when the benefits of faster responding outweigh the delay in initiating a response.