Bilingualism, inhibition, and executive processing: Evidence from Stroop color naming, proactive interference, task-switching, and working memory.

摘要

The present study tested the hypothesis that bilinguals develop superior executive processes, especially those involving inhibition and interference, as a result of the constant management of two competing language systems. Three studies compared monolingual and bilingual young adults on tasks measuring different executive and inhibition functions. In Experiment 1 we utilized the classic Stroop task to compare bilinguals and monolinguals on their ability to override the habitual tendency to read words while focusing on naming the color in which color words were printed. We found an interaction effect between language group and trial congruency on reaction times (RTs) indicating that the magnitude of difference between congruent and incongruent trials was greater for the monolinguals compared to bilinguals. While the two groups had similar RTs for the congruent trials, bilinguals responded faster to the incongruent trials compared to their monolingual counterparts. This was attributed to a more efficient prepotent response inhibition function, or an enhanced ability to deliberately suppress dominant responses as a function of bilingualism. Findings from Experiment 2 revealed that a different group of young bilinguals had smaller build-up of proactive interference (PI) in a short-term memory task compared to monolinguals. This was further attributed to a more efficient resistance to interference mechanism that operates to remove no longer relevant information from working memory (WM). In Experiment 3, we compared young monolingual and bilingual adults on tasks that tap three separate executive processing functions - task shifting, monitoring and updating of WM representations, and prepotent inhibition. The plus-minus task was used to measure the function of shifting, while the counting span task and the Stroop task were used to measure the functions of updating and inhibition, respectively. Results replicated the pattern of findings from our first experiment on Stroop interference and further revealed bilingual advantage in counting span but not in cost of shifting between the operations of addition and subtraction. These findings provided empirical support for the assumption that bilingualism affects some executive functions, specifically those involved in updating WM and in interference control as in Stroop and PI, although other executive functions such as task switching are unaffected.