Investigating multilingual adolescents’ cognitive and codeswitching performance: an exploratory application of language control models
Keywords: cognitive tasks
switch costs
Adaptive Control Hypothesis
Control Process Model
multilingualism
psycholinguistics
code-switching
Inhibitory Control
Lebanon
switching paradigm

Different interactional settings require multilingual speakers to switch from one language to another (i.e., to ‘codeswitch’) or to speak in one language only. This ability to alternate languages, or adhere to one language, involves a language control mechanism, a core element of Green’s (1998) Inhibitory Control Model (ICM) which proposes to explain how bilinguals regulate control of their language systems. Recently, Green and colleagues (Green & Abutalebi, 2013; Green & Li, 2014; Green, 2018) have extended this model by putting forth the Adaptive Control Hypothesis (ACH) and the Control Process Model (CPM) which take into account external and internal variables, such as language proficiency and code-switching habits, which may influence language choice. While the ICM has been generally supported, the ACH and CPM have not been extensively investigated. The present study explores the application of the aforementioned models and hypothesis in a multilingual context by examining balanced and unbalanced multilingual speakers as they switch between three languages. It also examines how language proficiency, self-reported code-switching behaviour, and other individual differences influence cognitive and code-switching task performance. Another aim of the project is to assess whether having a high proficiency in a third language confers additional cognitive and/or linguistic benefits. Sixty adolescent participants (aged 17-18), 30 French-immersion students and 30 English-immersion students, were recruited in Lebanon, a multilingual country where French-English-Arabic code-switching is ubiquitous, to perform cognitive and linguistic tasks. A Flanker task, the arrow Simon task, and a backward digit-span task were also administered to examine conflict monitoring, inhibitory control, and working memory, as well as possible correlations between cognitive and linguistic task performance. Participants also performed a picture-naming task and a narration task which allowed the examination of switch costs and fluency, respectively. It was predicted that the French-immersion participants, given their frequent trilingual code-switching and higher proficiency level in their third language, would outperform their English-immersion counterparts, whose use of French is minimal, in both domain-general and linguistic tasks. Results, however, indicated that the two groups performed similarly in cognitive tasks. However, on the linguistic tasks, French-immersion (more balanced) participants exhibited different patterns from their English-immersion counterparts (who were less balanced) on several conditions of the trilingual picture-naming task and on the narration task in the single-language condition. Switch costs differed across the three languages for both groups, with the strongest language(s) requiring increased inhibition, thus lending support to the ICM and CPM. Language experience, including frequency of code-switching and salient-cue detection, was also highly correlated with performance on both linguistic and cognitive tasks, therefore lending support for the ACH. Implications of the role of the third language are discussed in terms of the types of tasks employed in this study, and discussions of the concept of language proficiency and habitual code-switching experiences vis-à-vis the control processes in both models are offered.