Lateralization of lexical processing in monolinguals and bilinguals

Aims and objectives: This study aims to investigate how lexical processing (LP) is organized in early Turkish-English bilinguals and Turkish monolinguals. Methodology: We used a visual hemifield paradigm where bilingual (n = 48) and monolingual (n = 53) participants performed a lexical decision task. Bilingual participants performed the task in both their languages. Data and analysis: We recorded response times (RTs) and the accuracy rates (ARs) of the participants. An analysis of variance and t-test were run to analyze the bilingual and monolingual data, respectively. Findings: The results obtained from the analysis of the RTs and ARs for the Turkish and English words showed a balanced hemispheric organization in LP in bilingual speakers. The RTs for Turkish words in the monolingual group provided supportive evidence for the predominant role of the left hemisphere in LP. However, no significant difference was found in the accuracy of their answers, suggesting that the monolingual participants' performance was not influenced by visual field of presentation of the words. Finally, the comparison of the two groups revealed that bilingual participants' performance was inferior to monolinguals' in speed and accuracy of processing of words presented in both visual fields. This result gives further support for the differential representation of LP in monolinguals and bilinguals. Originality: The psycholinguistic literature abounds with studies of LP in bilinguals and monolinguals from a variety of language backgrounds; however, there is much less data regarding the brain correlates of LP in Turkish-English bilinguals and Turkish monolinguals. Implications: Since Turkish-English bilinguals and Turkish monolinguals are underrepresented in the literature as compared to the population who speak other languages with alphabetic writing, this study provides preliminary data for future studies. Limitations: We did not control for gender or lexical factors such as orthographic neighbors when designing the word sets used as stimuli.