Investigating the neural time course of stroop interference in bilinguals: An ERP study

Coderre, E. , Conklin, K. & van Heuven, W.

The University of Nottingham

The ‘bilingual advantage’ on the Stroop task may be attributed to enhanced executive control resulting from non-selective access to the bilingual lexicon or to slower lexical access in bilinguals due to lower relative frequency of language use. Varying the stimulus onset asynchrony (SOA) of stimuli presentation can elucidate the contributions of semantic and cognitive control processes in order to understand the locus of this bilingual advantage. In the present study a Stroop task with concurrent EEG was performed by Chinese-English bilinguals in their first (L1: Chinese) and second (L2: English) languages, using three SOAs: -400 ms (word appeared 400 ms before the colour), +400 ms (colour appeared 400 ms before the word) and 0 ms (simultaneous presentation). Previous Stroop ERP studies have identified an N450 component, related to conflict detection, and a late positive component (LPC), related to post-conflict resolution processes. Additionally, the latencies of these components are known to be affected by SOA manipulations in monolinguals (Appelbaum et al., 2009; Coderre et al., submitted). The L1 ERP data of the current study showed the same components and latency patterns as monolinguals: the N450 and LPC were shifted significantly forward in the -400 ms SOA compared to the 0 ms SOA, and no LPC occurred in the +400 ms SOA. Large differences in the non-linguistic control condition also appeared, indicating orthographic processing differences between Chinese and English. In the L2, the ERP data showed the same components and latency patterns as monolinguals, as well as large control differences, indicating linguistic processing differences due to proficiency in English. The results are discussed in terms of the bilingual advantage hypothesis, the weaker links hypothesis, and the temporal delay assumption.