Previous developmental studies reported bilinguals’ Theory of Mind (ToM; the ability to take on another's perspective) develops differently than monolinguals. We conducted a scoping review to evaluate how researchers assess bilinguals’ ToM and whether they characterize bilinguals’ lived experiences. We analyzed 53 publications examining ToM in bilinguals, with most papers studying children (n = 42; 79%). We identified 96 different tasks used across these 53 papers. The most common are 46 (48%) cases of the false-belief task, a cognitive-focused task using story vignettes. Few tasks target other types of ToM, such as ToM in social settings or taking others’ emotional perspectives. Furthermore, only half of the papers reported language history (n = 28, 53%) and exposure (n = 25, 47%), limiting the inferrability of ToM and language experiences. Expanding how we study ToM in bilinguals will improve our understanding of the intersection of bilingualism and ToM.

In applied linguistics generally and bilingualism research in particular, psychological variables remain a much under-investigated sub-category of individual differences compared with cognitive ones. To better understand the under-researched psychological effects of bilingualism, this study investigated well-being, a psychological construct, based on a big-data survey. Drawing upon a national survey (N = 12,582), we examined the influence of bilingualism (operationalised as foreign language (FL) proficiency) and 13 sociobiographical variables (e.g., socio-economic status, SES) on well-being. Among these 14 initial independent variables, perceived social fairness, SES, and health emerged as important predictors for well-being, with FL proficiency and national language (NL) proficiency as potentially important predictors; crucially, FL proficiency was more important than NL proficiency. As the first systematic attempt to link bilingualism with well-being, our study advocates (1) a more holistic perspective towards language (including NL and FL(s)) in any bilingual context and (2) fuller use of effect sizes.

Personal pronouns can potentially be resolved in logical syntax by means of variable binding (VB) or at the discourse-representational level through coreference assignment (CR). Previous research suggests that real-time reference resolution is guided more strongly by discourse-level cues in a non-native language (L2) than in a native language (L1). Here we use the VB/CR distinction to further test this hypothesis. Using eye-movement monitoring during reading and a complementary questionnaire task, we compared L1 German and L1 Russian/L2 German speakers’ resolution of object pronouns. While both our participant groups ultimately preferred CR over VB interpretations, only the L2 participants showed evidence of favouring a sentence-external CR antecedent from early on during processing. Our L1 group, by contrast, favoured a VB antecedent during processing. The observed L1/L2 processing differences reveal divergent antecedent search strategies, with L2 but not L1 speakers being primarily guided by discourse-level cues during real-time comprehension.

When a bilingual speaker has a larger linguistic sub-system in their L1 than their L2, how are L1 categories mapped to the smaller set of L2 categories? This article investigates this “subset scenario” (Escudero, 2005) through an analysis of laterals in highly proficient bilinguals (Scottish Gaelic L1, English L2). Gaelic has three lateral phonemes and English has one. We examine acoustics and articulation (using ultrasound tongue imaging) of lateral production in speakers’ two languages. Our results suggest that speakers do not copy a relevant Gaelic lateral into their English, instead maintaining language-specific strategies, with speakers also producing English laterals with positional allophony. These results show that speakers develop a separate production strategy for their L2. Our results advance models such as the L2LP which has mainly considered perception data, and also contribute articulatory data to this area of study.

Text comprehension frequently demands the resolution of no longer plausible interpretations to build an accurate situation model, an ability that might be especially challenging during second language comprehension. Twenty-two native English speakers (L1) and twenty-two highly proficient non-native English speakers (L2) were presented with short narratives in English. Each text required the evaluation and revision of an initial prediction. Eye movements in the text and a comprehension sentence indicated less efficient performance in the L2 than in L1 comprehension, in both inferential evaluation and revision. Interestingly, these effects were determined by individual differences in inhibitory control and linguistic proficiency. Higher inhibitory control reduced the time rereading previous parts of the text (better evaluation) as well as revisiting the text before answering the sentence (better revision) in L2 comprehenders, whereas higher proficiency reduced the time in the sentence when the story was coherent, suggesting better general comprehension in both languages.

The effects of bilingual language experience on cognitive control are still debated. A recent proposal is that being bilingual enhances attentional control. This is based on studies showing smaller effects of the nature of the preceding trial on the current trial in bilinguals (Grundy et al., 2017). However, performance on such tasks can also be accounted for by lower-level processes such as the binding and unbinding of stimulus and response features. The current study used a Partial Repetition Cost paradigm to explicitly test whether language experience can affect such processes. Results showed that bi- and monolinguals did not differ in their responses when the stimulus features were task-relevant. However, the bilinguals showed smaller partial repetition costs when the features were task-irrelevant. These findings suggest that language experience does not affect lower-level processes, and supports the view that bilinguals exhibit enhanced attentional disengagement.

Previous research examining the factors that determine language choice and voluntary switching mainly involved early bilinguals. Here, using picture naming, we investigated language choice and switching in late Dutch–English bilinguals. We found that naming was overall slower in cued than in voluntary switching, but switch costs occurred in both types of switching. The magnitude of switch costs differed depending on the task and language, and was moderated by L2 proficiency. Self-rated rather than objectively assessed proficiency predicted voluntary switching and ease of lexical access was associated with language choice. Between-language and within-language switch costs were not correlated. These results highlight self-rated proficiency as a reliable predictor of voluntary switching, with language modulating switch costs. As in early bilinguals, ease of lexical access was related to word-level language choice of late bilinguals.

We investigated the neurophysiological mechanisms underlying bi-alphabetic reading using event-related potentials (ERPs). Brain activity was recorded using EEG in a group of Russian–English biliterates during a reading-aloud task with familiar and novel words. Capitalizing on a partial overlap between the Roman and Cyrillic alphabets, the stimuli were presented in L1 Cyrillic, L2 Roman, or in an ambiguous script, in a counterbalanced fashion. The results revealed functional dissociation between the stimuli in terms of processing their graphemic ambiguity. The interference caused by L1-L2 script inconsistencies in novel wordforms was detected at a late processing stage, reflected in N400 response enhancement for unfamiliar script-ambiguous items. Conversely, familiar ambiguous and L2 words showed no N400 increase but demonstrated an early enhancement of the P200 component in comparison to those presented in L1. These results indicate the use of a whole-word reading strategy for familiar words even in ambiguous script, likely triggered by an automatic activation of well-established lexico-semantic representations. The absence of similar top-down mechanisms for novel ambiguous-script words likely results in increased grapheme-to-phoneme decoding effort, with important implications for L2 reading and vocabulary acquisition.

This study explores the implications of Talmy's (2000) motion event typology and its subsequent articulations in relation to Slobin's (1996, 2006) thinking-for-speaking hypothesis for the early successive bilingual acquisition of Uyghur (verb-framed) and Mandarin Chinese (equipollently-framed). Specifically, it examines how 4-, 6-, 8- and 10-year-old bilingual children acquire motion expressions in their L1 and L2 respectively, and how cross-linguistic influence shapes their L2 acquisition process. Results show that, in their L1 Uyghur, bilinguals follow general developmental trajectories observed for children acquiring verb-framed languages. While sensitive to the equipollent Chinese system from early on, due to L1 and other factors, bilinguals fully converge on the Chinese pattern only at age 10, a feat in place in monolinguals from age 3. Our findings highlight that bilingual children do eventually come to develop language-specific thinking-for-speaking patterns in their L2, but they traverse a distinct developmental path.

Little is known about the neural changes that accompany sign language learning by hearing adults. We used ERPs and a word-sign matching task to assess how learning impacted the N400 priming effect (reduced negativity for translations compared to unrelated trials). English monolinguals (N = 32) learned 100 ASL signs – half highly iconic (meaning was guessable), half non-iconic. In contrast to non-iconic signs, little learning was needed for the highly iconic signs as translation accuracy was similar pre- and post-learning. Prior to learning, an N400 priming effect was observed only for iconic signs. After learning, the size of the priming effect increased for non-iconic signs (replicating word learning studies) but decreased for iconic signs. For deaf ASL signers (N = 20), iconicity did not modulate the size of the N400 priming effect. We conclude that the impact of iconicity on lexico-semantic processing is reduced following learning, as signs are integrated into an emerging visual-manual lexicon.

This study investigates whether the cognitive reappraisal strategy is influenced by the participant's language (native/foreign) when confronting a fearful stimulus. Sixty participants with subclinical phobia of cockroaches were exposed to several phobic and neutral pictures while they used cognitive reappraisal in their native language or a foreign one. Electrodermal activity, pupil dilation, and self-reports of affective valence and arousal were collected. Results showed that participants in the foreign context were more effective at using reappraisal to reduce valence self-ratings compared to using no regulation. Also, participants in the foreign context showed greater pupil size when reappraising their emotions, compared to the non-regulation condition. Depending on the language, no differences were found for arousal self-reports or electrodermal activity when using reappraisal. These results suggest that using a foreign language could be advantageous in reducing the negative valence through reappraisal. Psychophysiological results are discussed in light of cognitive effort studies.

The vocabulary of bilingual children is determined by various linguistic factors that develop depending on the language input and individual factors of these children. To understand vocabulary development and to be able to support these children accordingly, the assessment instruments essentially need to be adapted to this individual process. The current study examined factors influencing productive vocabulary performance by means of explanatory item-response models on a sample of 126 German monolingual and Turkish—German bilingual preschool children aged between 3 and 6 years. We analyzed item features with respect to lexical category, length, frequency, age of acquisition, and complexity in dependence of the language background of the children. Apart from a general delay in the development and some language specific characteristics, the results indicate a parallel shifted acquisition of vocabulary in bilingual children, which is nonetheless shaped by the same factors as in monolinguals.

Previous research suggests that bilingual language control requires domain-general cognitive control. Recent research suggests that exploration of individual differences is key for understanding the relationship between bilingual language control and cognitive control. The current study used multi-voxel pattern analysis (MVPA) to examine within-subject patterns of fMRI activity in the dorsolateral prefrontal cortex (DLPFC) during bilingual language switching and non-linguistic task-switching. We hypothesized that bilinguals would have identifiable, within-subject patterns of DLPFC activity for both types of switching and that bilinguals and monolinguals would differ in patterns of DLPFC activity for task-switching. We were unable to identify patterns of DLPFC activity associated with bilingual language switching. Task-switching was related to patterns of left DLPFC activity for both bilinguals and monolinguals, and there were identifiable patterns of right DLPFC activity for the bilinguals only. These findings suggest that the DLPFC is not the key brain structure connecting bilingual language and task-switching.

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.

Subcortical structures implicated in language control and processing adapt structurally with increasing language experience. However, the adaptation patterns across different subcortical structures remain unclear. Previous findings from bilinguals and multilinguals reveal renormalisation patterns, lending support to the Dynamic Restructuring Model (Pliatsikas, 2020). These patterns are composed of increasing volumes during the initial stages of language learning, and subsequent reductions as experience increases. T1-weighted images from 14 English monolinguals, 14 bilinguals, 14 trilinguals, and 14 quadrilinguals were obtained. The volumes of five subcortical regions implicated in language control and processing were compared amongst the groups. The findings showed group differences for every structure – caudate nucleus, nucleus accumbens, putamen, globus pallidus and thalamus. Complex patterns were unveiled for each structure, suggesting expansions and renormalisations that differ in trajectory for each group. These findings highlight the dynamic progression of subcortical adaptations, and support the notion of structural renormalisation as language experience grows.

Adults differ in the ease with which they acquire lexical tones in a non-native language. Individual differences have been attributed to several factors, such as the role that pitch plays in a learner's L1 to signal lexical meaning (L1 tonal status), the shape of the tones to be acquired (tone types), as well as extralinguistic factors (such as musical experience and working memory). Here, we ask whether learners from a spectrum of L1 tonal statuses (Dutch, Swedish and Japanese, and Thai) differ in their tone word learning facility, whilst we simultaneously investigate the effects of tone type, and musical experience and working memory. Our findings suggest that above and beyond L1 tonal status, the strongest predictor of tone word learning was pre-lexical tone processing (measured by a tone categorization task), although the strength of the link between pre-lexical and lexical processing may be modulated by L1 tonal status.

Bilingualism is a multifaceted experience that researchers have examined using various questionnaires to gain insights and characterize the experience. However, there are several issues related to questionnaire choice. To address this, we applied Content Overlap Analysis to seven prevalent bilingualism questionnaires, assessing their affinity. We found little overlap in these questionnaires; most had fewer than 15% of items in common, suggesting they capture different aspects of the bilingual experience and provide complementary rather than redundant data for researchers. Our investigation highlights the importance of choosing a bilingualism assessment tool to carefully fit research questions and sample language experiences.