Ageing and bilingualism: Absence of a “bilingual advantage” in Stroop interference in a nonimmigrant sample

Abstract

Previous research has found an advantage for bilinguals relative to monolinguals on tasks of attentional control. This advantage has been found to be larger in older adults than in young adults, suggesting that bilingualism provides a buffer against age-related declines in executive functioning. Using a computerized Stroop task in a nonimmigrant sample of young and older monolinguals and bilinguals, the current investigation tried to replicate previous findings of a bilingual advantage. A bilingual advantage would have been demonstrated by smaller Stroop interference (i.e., smaller increases in response time for incongruent than for neutral trials) for bilinguals than for monolinguals. The results showed that bilingual young adults showed a general speed advantage relative to their monolingual counterparts, but this was not associated with smaller Stroop interference. Older adults showed no effect of bilingualism. Thus, the present investigation does not find evidence of a bilingual advantage in young or older adults and suggests limits to the robustness and/or specificity of previous findings.

Keywords:

• Ageing
• Bilingualism
• Stroop interference
• Bilingual advantage

Acknowledgments

The authors would like to thank the members of the Cognitive Psychophysiology Laboratory for their help with participant recruitment and data collection—specifically, H. Duncan, L. Karpowicz, and C. McHenry. Thank you to B. Woodside and N. Segalowitz for helpful comments on a previous version of this manuscript. Preliminary data were presented at the 11th Cognitive Aging Conference, Atlanta, Georgia, April 2006. This work was supported by a Canadian Institutes for Health Research Frederick Banting and Charles Best Canada Graduate Scholarship awarded to S. Kousaie and Grant 203751 from the Natural Sciences and Engineering Research Council of Canada (NSERC) to N. A. Phillips.

Notes

¹Given the difficulty recruiting participants who met our strict language criteria, all the groups were not matched with respect to gender. Evidence for gender differences in Stroop performance is inconsistent (see Macleod, 1991; but see Baroun & Alansari, 2006). For this reason, we compared males and females on the three conditions of the Stroop task for each age and language group. The only significant gender difference that was found was in the older bilinguals; females performed faster than males overall. Given that the speed advantage was a general one, and we were interested in Stroop interference, this was not considered further.

² In total, 12 older adults (5 older monolinguals and 7 older bilinguals) with scores between 23 and 25 were included in the study. Although these older adults scored below the cut-off for normal cognitive functioning, interaction with the experimenter and performance on other cognitive tasks provided no indication of impaired cognitive function. Critically, an independent-samples t test indicated no difference in MoCA scores between the two language groups (p = .68).

³ The Public Health Agency of Canada (2002) reported that in 1996, 60% of Canadian seniors never completed high school (i.e., corresponding to 11 years of education in our measurement), with one third having no secondary education.