Cognitive control-e.g. the abilities to pay attention, to ignore irrelevant input, and to switch between tasks- has received much attention in recent literature. Since both of their languages are activated in parallel, bilinguals have been suggested to have improved cognitive control skills in both the linguistic and non-linguistic domain (e.g., Bialystok, 2017), but inconsistent results (e.g., Hilchey, Saint-Aubin, & Klein, 2015) have lead to a heated debate in the field. However, when found, the effects of bilingualism on cognitive control appear to be generally positive (Valian, 2015). Furthermore, earlier bilingualism has been linked to greater cognitive benefits (Yow & Li, 2015), and Green and Abutalebi's (2013) Adaptive Control Hypothesis (ACH) suggests that the bilingual environment also plays a role. The aim of the current study is to investigate the role of the Age of Acquisition (AoA) of the second language on cognitive control in young adult bilinguals in two different linguistic environments, as well as to examine the underlying processes of cognitive control via event-related brain potentials (ERPs). Two research questions are focused on: 1) Which, if any, cognitive control abilities are enhanced by bilingualism? and 2) Does the type of bilingual experience modulate observed effects? The present study uses the non-linguistic Attention Network Test (ANT; Fan et al., 2002), in which sets of arrows appear with a central target arrow in either a congruent (e.g. ← ← ← ) or incongruent (e.g. ← → ← ) condition, to examine Alerting, Orienting, and Executive Control networks, and a linguistic Stroop task (Stroop, 1935), in which colour terms appear in congruent (i.e. the word "red" presented in red font) and incongruent (i.e. the word "red" presented in green font) conditions, to examine language processing of English-French bilinguals in Canada and in Japanese-English bilinguals in Japan. In addition, Canadian participants also completed an ERP version of the Stroop task to examine possible underlying differences. The results of this series of experiments revealed a complex, yet interesting picture of bilingual cognitive control: although bilingual advantages were not consistent, there was support for earlier bilingualism being more beneficial to cognitive control. Particularly, results show Executive Control advantages for Simultaneous bilinguals, and significant differences between Simultaneous and Early Sequential bilinguals (typically grouped together as "early") in the Stroop task, demonstrating that balanced, proficient bilingualism enhances both linguistic and non-linguistic control. Interestingly, these effects only become apparent when both languages are mixed in the task, in line with suggestions that young adults’ cognitive resources need to be maximally taxed before advantages become apparent. Indeed, ERP results confirmed a greater engagement of cognitive resources in the more difficult version of the task. Although AoA and environment turned out to be confounded, there were still differences between Canadian and Japanese participants. Most notably, Canadian participants appeared to have better Executive Control. Taken together, the current work concludes that despite increased processing load, bilingual cognition does not suffer. Instead, cognition may receive a boost from dual language experience in some cases. Several rarely-explored factors were examined, and the complex results suggest possible areas that would benefit from further exploration, as well as raise interesting questions for future research.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/38063 |
| Date | 04 September 2018 |
| Creators | Vinerte, Santa |
| Contributors | Sabourin, Laura |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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