Semantic context effects in monolingual and bilingual speakers

Most models of word production converge on the assumption that selecting a specific word to name is a competitive process. Monolingual speakers experience lexical competition in their spoken language (i.e., within-language competition), but bilingual speakers who constantly juggle two sets of lexical items face within- and between-language competition. It has been argued that one of the reasons bilingual speakers perform poorly in linguistic tasks compared to monolinguals is the interference from the non-target language. However, this constant juggling of two languages has also been proposed to lead to better executive control abilities in bilinguals. The aim of this research was to determine the relationship between increased lexical competition as induced by semantic context manipulation in the blocked-cyclic picture naming paradigm, and executive control processes in bilingual and monolingual speakers. We implemented the blocked-cyclic picture naming paradigm to induce increased lexical competition and employed independent executive control tasks to understand its role in reducing increased lexical competition. We also computed delta plots – size of interference effects as a function of naming latencies – to investigate the type of inhibition involved in the blocked-cyclic picture naming paradigm. In this paradigm, objects to be named were presented in close succession, either from the same semantic categories (homogeneous: elephant, lion, deer, tiger, and cat) or different ones (heterogeneous: pear, shoes, lips, saw, and deer). Naming latencies are longer in the homogeneous context due to the heightened activation of competitors, and the difference in latencies between the homogeneous and heterogeneous contexts is referred to as semantic context effect. The participants were 25 young, healthy Bengali-English bilinguals and 25 healthy, age-, gender- and education-matched English monolinguals. All participants performed a blocked-cyclic naming task in English as well as three independent executive control tasks, tapping into their inhibitory control (Stroop task), mental-set shifting (colour-shape switch task), and working memory (backward digit span task). The key group differences were as follows: bilinguals showed less semantic context effect and more semantic facilitation on the first presentation cycle, applied more selective inhibition in both blocked-cyclic picture naming and Stroop tasks as measured by delta plots, showed better inhibitory control (Stroop task) and shifting abilities, but showed comparable working memory span. The correlation findings for both groups were as follows: slope of the slowest delta segment correlated with the magnitude of the semantic context effect in the blocked-cyclic naming task, no correlation between the slope and interference effect in the Stroop task, no correlation between slope of the two tasks, and no correlations between the semantic context effect with any of the measures derived from the independent executive control tasks. This is the first study to establish that bilinguals are less affected by semantic context manipulation and show a reduced interference effect for the longest naming latencies, compared to monolinguals. It also illustrates that even in a challenging linguistic task that heightens lexical competition, bilinguals performed better than monolinguals. This challenges the notion that bilinguals are disadvantaged compared to monolinguals in linguistic tasks, and we conclude that this study provides evidence for the advantage of bilingualism in linguistic tasks where executive control demands are higher.publishe