Abstract

This thesis presents research that addresses several questions with respect to findings demonstrating superior performance in bilinguals relative to monolinguals on cognitive control tasks, which has been termed the “bilingual advantage”. Chapter 2 reports a study investigating the presence of a bilingual advantage in a homogeneous sample of young and older adults using a Stroop task. The results demonstrated that, in young adults there was a general speed advantage for the bilinguals, but this did not translate to a decrease in Stroop interference as would be expected if there was an advantage for the bilinguals. There was no difference in performance between the monolingual and bilingual older adults.
Chapter 3 reports research further investigating the possibility of a bilingual advantage in young adults using an array of tasks (i.e., Stroop, Simon, and Eriksen flanker). In addition to behavioural measures, electrophysiological measures that I reasoned would be more sensitive to detecting language group differences were included. Behaviourally no differences between monolinguals and bilinguals were found, replicating the results from chapter 2. However, I found differences in electrical brain activity between the two groups suggesting differences in conflict processing. Specifically, differences were observed in N2 amplitude, which is thought to reflect conflict monitoring; P3 latency and amplitude, which is thought to reflect stimulus categorization time and resource allocation; and the amplitude of the error-related negativity, which is thought to reflect conflict on error trials. These findings were not consistent across the three tasks, and given the lack of behavioural differences between the groups the observed electrophysiological differences do not necessarily represent an advantage for the bilinguals.
The research presented in my thesis further examines and characterizes the previously observed advantage for bilinguals relative to monolinguals on tasks of cognitive control using improved methodology. I included a homogenous sample of monolingual and bilingual participants, used multiple tasks in the same participants, and included electrophysiological methodology capable of measuring brain activity during task performance. It is concluded that under certain conditions differences between monolinguals and bilinguals do emerge, but these differences do not necessarily represent an advantage.