ERP measures of the effects of age and bilingualism on working memory performance

Previous research has suggested that bilinguals may exhibit cognitive advantages over those who are monolingual, although conflicting results have been reported. This advantage may be heightened in older adults, because of age-related cognitive decline. However, the effects of bilingualism on working memory performance in older adults remain unknown. The current study uses electroencephalography to measure brain activity (event-related potential; ERP) differences between young and older monolinguals and bilinguals during a delayed matching-to-sample task. Although there were no effects of bilingualism in behavioral measures, differences were observed in electrophysiological measures. While no Age by Language interaction was observed, several main effects were identified. Compared to young adults, older adults exhibited smaller N2 amplitudes and larger P2 and P3b amplitudes in the medium and high load conditions. Older adults also displayed an increased slow wave amplitude that occurred in conjunction with increased reaction time. ERP differences during difficult tasks in older adults suggest the use of compensatory mechanisms to maintain similar performance to the young adults. Bilinguals exhibited smaller N2 and larger P2 and P3b amplitudes than monolinguals. ERP differences observed in bilinguals may reflect differences in cognitive processing. However, in the absence of performance differences between monolinguals and bilinguals, interpreting a bilingual advantage in working memory processing is difficult.