This study investigated individual differences in bilinguals’ use of proactive and reactive control processes during an executive control task (the AX-CPT) in relation to aspects of the bilingual experience (e.g., second language proficiency). Participants were presented with cue-target letter pairs, one letter at a time (AX, AY, BX, or BY; B and Y are any letter other than A or X) and were instructed to press the “yes” button for AX pairs and the “no” button for any other pair. They completed three blocks which varied in terms of the most frequent trial type (AX-70% vs. AY-70% vs. BX-70%). Event-related brain potentials (ERPs) were recorded from 15 young adult bilinguals during the AX-CPT. The N2, an ERP related to conflict detection, was analyzed in conjunction with behavioural performance.
Individual variations in cognitive control strategy were differentially associated with aspects of bilingualism in the AX-70 and AY-70 blocks. In the AX-70 block, greater engagement of proactive control was associated with shorter overall reaction times (RTs), lower accuracy, and enhanced conflict detection. In the AY-70 block, a proactive strategy was associated with lower accuracy, but similar RTs compared to a reactive strategy.
Different patterns of association were found between self-reported language-switching behaviours and cognitive control strategy in the AX-70 block compared to the AY-70 block.
The results support the idea of individual differences in the relative use of proactive and reactive mechanisms in bilinguals. These differences were related to aspects of language-switching which is an important source of interindividual variability among bilinguals
