Event related potentials of bilingual performance on a color-word stroop task for the overt response modality
Overt and covert response modalities often pattern similarly in amplitude, latency, and distribution in ERP studies looking at the monolingual Stroop task. However, there is support for the bilingual brain being different from monolinguals, which could potentially cause additional conflict during a bilingual color-word Stroop task paradigm as a result of the added motor planning of speech in the overt response. This could alter the justification that covert responses can be reported alone since the overt response easily causes contamination of ERPs from muscle noise. Using a sample of Spanish-English bilinguals, these assumptions were tested, and the N200 and N450 ERP components were analyzed to determine if there was increased modulation by language and color as a result of additional conflict caused by bilingualism. The N200 showed a color effect in the overt response that was not reported in previous studies, suggesting there was an increased need for inhibitory control. However, the determination of modulation by language conflict in the N450 was inconclusive due to technical errors in the methodology of the experiment. Furthermore, while monolingual studies were able to successfully compare ERP components across overt and covert modalities, this bilingual study was not capable of similarly doing as such. The motor component of the overt task caused an increase in noisy data, which led to greater data rejection and overall loss of subjects. In sum, while this experiment was unable to determine if the N450 was modulated by a language as a result of the bilingual Stroop effect, it was helpful in demonstrating the importance of response modality in ERP experiments.