The Relationship Between Bilingualism and Control Aspect of Intelligence: A Study of Persian-speaking Individuals.

INTRODUCTION: The study of the relationship between bilingualism and the possible impact it might have on the control aspect of intelligence of adults in general and preschool children, in particular, has always been the subject of controversy for researchers. This research, following the related findings and gaps in the literature and inspired by Craik and Bialystok's (2005) framework, tries to divulge whether bilingualism could be related to the control aspect of intelligence. As our secondary goal, we also tried to see whether there are correlations between different tests assessing control.

METHODS: In this descriptive correlational study, via the convenience sampling method, we selected our participants. Methods: In doing so, 10 age-gender-matched Mazandarani-speaking monolinguals and the same matched bilinguals have been selected. Moreover, the literacy and socioeconomic status of subjects have been controlled. The tests for assessing subjects' executive control included day-night Stroop, the dimensional change card sort (DCCS), test of variables of attention (TOVA), and the computerized attention network test (ANT). Our participants' performance in language proficiency task as well as control tasks was demonstrated. Furthermore, via the conduction of the Pearson correlation statistics, the relationships between the participants' performance in diverse control tasks and language task were investigated.

RESULTS: The results showed that bilinguals outperform monolinguals in all control tests except DCCS.

CONCLUSION: Bilingualism could provide children with an executive control advantage promoting them in tasks demanding thought and action control.

HIGHLIGHTS: Language proficiency is not necessarily related to an advanced attentional control.Mazandarani-speaking monolinguals and bilinguals perform equally in the "knowledge" domain of intelligence.Bilinguals' performance in the control task of intelligence was better than their monolingual counterparts.It was corroborated that intelligence is not a homogeneous psychological construct.Generally, in tasks requiring suppression, bilinguals outperform monolinguals.

PLAIN LANGUAGE SUMMARY: The investigation of the relationship between control aspect of intelligence and the statue of monolingualism or bilingualism has always been the subject of controversy. "Control" aspect signifies the ability of an individual to suppress the provoking stimuli, that is, to ignore the external stimuli in favor of an intended linguistic or non-linguistic element. Our major objective in this research was to compare the performance of Mazandarani-speaking bilinguals and monolinguals in diverse control as well as vocabulary assessment tasks. Specifically, we wanted to see whether bilingual children could perform better than monolingual children in tasks requiring the inhibition capability. Furthermore, we attempted to investigate whether there were correlations between different control assessment tasks. Extending previous researches, we administered two additional cognitive tasks, namely, test of variables of attention (TOVA) and day and night task to evaluate our participants' control capability. In linguistic (vocabulary) proficiency assessment task, Peabody picture vocabulary task (PPVT), we did not find bilinguals' advantage over monolinguals. In contrast, bilinguals outperformed their monolingual counterparts in all other control tasks except dimensional change card sort (DCCS). Meanwhile, strong correlations between most control tasks were observed. The results corroborated that bilingual children outperformed their monolingual counterparts in tasks demanding strong thought and action control. Also, the conduction of most control tasks might be more challenging for monolinguals, and bilingual children, thanks to their linguistic statutes, could ignore irrelevant response or stimuli more easily, and perform better in the majority of cognitive control demanding tasks.