Bilingualism is an experience that varies across a continuum and can change across the lifespan. Psychometric research is an underexplored avenue with the potential to further our understanding of the mechanisms and traits underlying bilingual experiences. Here, we developed and validated a social network questionnaire to measure sociolinguistic features in 212 individuals via personal social network. Confirmatory factor analysis examined the measurement structure of the variables. Compared to a one-factor model, the best fitting model was a two-factor model in which the language experience of the individual (i.e., ego) and the language experience of the individual's network (i.e., alters) were correlated latent factors under which aspects of the bilingual experience loaded. Additional analyses revealed other potential ways to examine the data in future analyses. These results provide the first measurement model of bilingual experiences, and provide support for theoretical accounts suggesting differential neuropsychological outcomes based on individual bilingual variability. The results also support the use of social network tools to capture differences in bilingualism.

The purpose of the current report is to study the effects of language distance on noun and verb processing in bilingual speakers. We recruited two groups of bilingual speakers: one group spoke two typologically distant languages (Cantonese and English) and the other group spoke two typologically similar languages (Mandarin and Cantonese). Participants named object and action pictures in their first language. We controlled psycholinguistic properties of words such as frequency, AoA, imageability, name agreement, visual complexity, familiarity, and participants’ bilingual language experiences. Our findings revealed a significant role for language distance. We observed a difference between noun and verb processing in the similar language pair (Mandarin–Cantonese) due to interference induced by language similarity. However, in the distant language pair (Cantonese–English), the difference disappeared because of the lack of cross-language interference. Our findings support that current and future models of bilingual language processing should take into account the effects of language distance.

This study investigates bilingualism-induced neuroplastic and cognitive-reserve effects in the Caudate Nucleus (CN), a structure believed to support both bilingual language control and domain-general executive functioning. We computed a generalized bilingualism index incorporating several dimensions of bilingual experience in a sample of bilingual young adults and tested whether this index would predict behavioral executive performance (measured using a Flanker task) and volumetric differences in the CN. Moreover, we investigated whether bilingualism mitigates the relationship between CN volume and executive performance, a sign of cognitive reserve. Our results indicate that bilingualism facilitates executive performance and induces an inverted U-shaped neuroplastic trajectory in bilateral CN, consistently with the view that structural increases are replaced by functional improvements as bilingual experience progresses. The emergence of bilingualism-induced cognitive reserve effects in CN further supports the view that bilinguals rely progressively less on the availability of structural resources in the face of increased functional efficiency.

The psycholinguistic literature suggests that the length of a to-be-spoken phrase impacts the scope of speech planning, as reflected by different patterns of speech onset latencies. However, it is unclear whether such findings extend to first and second language (L1, L2) speech planning. Here, the same bilingual adults produced multi-phrase numerical equations (i.e., with natural break points) and single-phrase numbers (without natural break points) in their L1 and L2. For single-phrase utterances, both L1 and L2 were affected by L2 exposure. For multi-phrase utterances, L1 scope of planning was similar to what has been previously reported for monolinguals; however, L2 scope of planning exhibited variable patterns as a function of individual differences in L2 exposure. Thus, the scope of planning among bilinguals varies as a function of the complexity of their utterances: specifically, by whether people are speaking in their L1 or L2, and bilingual language experience.

We report a study that investigated executive functions in four groups of participants that varied in bilingual language experience, using a task that measured two theoretically motivated mechanisms of cognitive control (proactive and reactive control). Analyses of accuracy based on aggregated measures suggested an advantage in early highly proficient bilinguals over late passive bilinguals. However, when we factored in individual variability using mixed-model regression with a full random effect structure, we only found a marginal effect of language experience. Our results emphasise the importance of including individual variability when studying bilingualism, and highlight a fundamental consideration in research on the relation between language and attention – namely, the need for a theory-driven approach to measuring cognitive control through laboratory tasks.

The investigation of bilingualism and cognition has been enriched by recent developments in functional magnetic resonance imaging (fMRI). Extending how bilingual experience shapes cognition, this review examines recent fMRI studies adopting executive control tasks with minimal or no linguistic demands. Across a range of studies with divergent ages and language pairs spoken by bilinguals, brain regions supporting executive control significantly overlap with brain regions recruited for language control (Abutalebi & Green). Furthermore, limited but emerging studies on resting-state networks are addressed, which suggest more coherent spatially distributed functional connectivity in bilinguals. Given the dynamic nature of bilingual experience, it is essential to consider both task-related functional networks (externally-driven engagement), and resting-state networks, such as default mode network (internal control). Both types of networks are important elements of bilingual language control, which relies on domain-general executive control.

The Flanker and Number Stroop tasks, and the Wisconsin Card Sorting Test (WCST) were adopted to examine how bilingualism and public speaking training would contribute to cognitive control differences among young adults. Four groups of participants (of similar cultural and language backgrounds) were tested: monolinguals, general bilinguals, L1 public speaking bilinguals, and L2 public speaking bilinguals. Both ANOVA and multiple regression analyses showed that public speaking experience (esp. in L2) significantly contributed to conflict monitoring as tested in the global reaction times in the Flanker and Number Stroop tasks, whereas bilingualism (L2 verbal fluency, to be more specific) significantly contributed to mental set shifting as tested in the WCST. These results suggest that specific aspects of language experience, either in L1 or in L2, may incur enhancement in specific aspects of cognitive control, which has implications for bilingual advantage research.