Researchers have argued that grouping heterogeneous linguistic profiles under a dichotomous condition might mask the cognitive effects of bilingualism. The current study used two different analysis approaches (i.e., continuous versus dichotomous) to examine inhibitory control in a sample of 239 young adult bilinguals. Dividing the sample into dichotomous groups based on L2 proficiency (i.e., high-proficient versus low-proficient) and L2 AoA (i.e., early versus late) did not lead to reliable group differences in any of the measurements used. However, the use of a continuous measure revealed that higher L2 proficiency predicted better visual inhibition and earlier L2 AoA was associated with better auditory inhibition. Furthermore, the observed differences were limited to tasks involving stimulus–stimulus competition, but not stimulus–response competition. These findings shed new light on the importance of conceptualising bilingualism as a continuous measure rather than a dichotomous measure and previous research on bilingual performance in different cognitive tasks.

This paper examines the linguistic relativity principle (Whorf, 1956) by investigating the impact of grammatical gender on cognition in simultaneous bilinguals of three-gendered Ukrainian and Russian. It examines whether speakers of three-gendered languages show grammatical gender effects on categorisation, empirically addressing claims that such effects are insignificant due to the presence of the neuter gender (Sera et al., 2002). We conducted two experiments using a similarity judgement paradigm while manipulating the presence of neuter gender stimuli (Phillips & Boroditsky, 2003). Experiment 1, including neuter gender, revealed no significant effects, compatible with earlier studies on three-gendered languages. Conversely, Experiment 2, excluding neuter gender stimuli, showed significant language effects. Bilingual participants rated pairs as more similar when grammatical genders in both languages were congruent with the biological sex of a character. Significant effects were also found for pairs with mismatching grammatical genders in Ukrainian and Russian. Participants with higher proficiency in Ukrainian rated pairs as more similar when the grammatical gender of a noun in Ukrainian was congruent with the character’s biological sex, and incongruent in Russian. Our findings thus provide the first empirical demonstration that the exclusion of neuter gender online induces grammatical gender effects in speakers of three-gendered languages.

Multilingual language control is commonly investigated using picture-naming paradigms with explicit instructions when to switch between languages. In daily life, language switching also occurs without external cues. Cued language-switching tasks usually show a switch cost (i.e., slower responses on switch than non-switch trials). Findings of switch costs in response times are mixed for voluntary language switching. This pre-registered study uses a bilingual picture-naming paradigm to compare voluntary and cued language switching in 25 highly proficient Dutch-English bilinguals using EEG. We analysed the N2 ERP component and midfrontal theta oscillations, two common electrophysiological markers of cognitive control in task and language switching. We observed significantly smaller behavioural switch costs in the voluntary task. This suggests that voluntary language switching is less effortful than switching based on external cues. However, we found no electrophysiological switch effects in either task. We discuss factors which may contribute to the inconsistency between behavioural and electrophysiological findings.

We investigated three aspects of paired associate learning of vocabulary in an unfamiliar language: monolingual-bilingual differences, effects of dominance and language proficiency, and the possible role of associative strategies. Spanish–English bilinguals (48 English-dominant and 48 Spanish-dominant) and English-speaking monolinguals (n = 48) learned Swahili–English and Swahili-Spanish word pairs. Learning was assessed using cued recall (Swahili cue or Swahili response) and associative recognition tests. English-dominant bilinguals did not outperform English monolinguals on any learning measure. Cued recall accuracy was higher when learning through the dominant language than through the non-dominant language, whether the Swahili words were cues or responses. Proficiency scores in the known language were positively correlated with cued recall accuracy, whether the cue or the response was in Swahili, indicating that proficiency effects occurred not in retrievability of known words but in learning of associations. Bilingual and monolingual participants did not differ in their reported use of associative strategies.

Previous research on audiovisual input attests to a significant effect of on-screen text and proficiency on learning gains. However, there is scarce research on whether these factors affect viewers’ feeling of learning, a variable that can affect overall second language (L2) learning outcomes (Ellis, 2008). Moreover, there is a lack of research exploring whether viewing experience prompts viewers to switch from one viewing mode (subtitles, captions, no on-screen text) to another and what factors affect those choices. This study explores learners’ perspectives on learning from audiovisual input and their preferred viewing mode before and after participating in a prolonged viewing intervention. A total of 136 participants of varying L2 English proficiency levels (from A1 to C2) completed pre-viewing and post-viewing questionnaires. The results show that vocabulary and expressions were perceived to be learnt the most. The elementary proficiency group were more likely to be positive about learning from the intervention than higher proficiency students. Concerning the preferred viewing mode outside of the classroom, the participants favoured no on-screen text or first language (L1) subtitles over L2 captions. At the end of the intervention, the elementary-level participants found that viewing without any L1 support was too challenging for leisure viewing, while the intermediate- and advanced-level students gained confidence in watching without any textual support.

Using a voluntary object-naming paradigm, we examined if bilinguals with high or low L2 proficiency monitor their language selection and production according to their interlocutors' L2 language proficiency. Telugu (L1)–English (L2) bilinguals were introduced to audio-visual stimuli that consisted of animated interlocutors that were high or low proficient in English. In Experiment 1, interlocutors were presented at different frequencies in each block, and in Experiment 2, the presentation of each interlocutor was blocked. We predicted that the frequency of interlocutors would modulate language activation and selection. The participants named the objects language that came to their minds to respond to interlocutors. Indeed, consistent with our predictions, monitoring contexts induced by such interlocutors influenced latencies, language choice and switch-cost. High-L2 proficient participants employed higher language control than low-L2 proficient participants. These results support the hypothesis that bilinguals are sensitive toward their interlocutors' language proficiency and employ context-appropriate cognitive control.

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.

The Moral Foreign Language Effect (MFLE) is characterized by increased utilitarian decision-making when bilinguals respond to moral dilemmas in their foreign language. While previous research has given us a better understanding of this phenomenon, few studies have investigated how foreign language experience influences the MFLE. The present study investigated whether differences in foreign language proficiency, immersion, or dominance modulated the emergence of the MFLE. Mandarin–English bilingual young adults responded to a series of moral dilemmas in either their native or foreign language. Participants also provided ratings of permissibility and distress after reading each dilemma. We report a dilemma-specific MFLE that was modulated by differences in foreign language experience. Most significant was the observation that separable dimensions of foreign language experience interact when modulating the MFLE in a manner that is dilemma-specific. These findings emphasize the importance of considering differences in foreign language experience across multiple dimensions when investigating the MFLE.

Code-switching, switching between different languages within the same conversation, is a prominent feature in bilingual communication. This study aimed to elucidate to what extent the linguistic abilities and age of dual-language-learning preschoolers influence the frequency and purposes of code-switching (compensatory, to bridge linguistic gaps; preferential, to express content as fluently as possible; pragmatic, to phrase something appropriately for the situation). Parental code-switching ratings of 101 German/French–Turkish/Italian dual-language learners aged 32–78 months were analyzed. Generalized linear mixed models revealed positive but no negative effects of societal- and heritage-language skills on children's code-switching frequencies independent of switching purposes and with no evidence of age effects. Hence, code-switching across the preschool age mainly reflects high linguistic competences. Models with linguistically and psychometrically parallelized language scores indicated a strong switching tendency toward the societal language when proficiency in both languages is high, and away from the societal language when language proficiencies are low.

The multidimensionality of the bilingual experience makes the investigation of bilingualism fascinating but also challenging. Although the literature distinguishes several aspects of bilingualism, the measurement methods and the relationships between these aspects have not been clearly established. In a group of 171 relatively young Polish–English bilinguals living in their first-language environment, this study investigates the relationships between the multiple measures of bilingualism. The study shows that language entropy – an increasingly popular measure of the diversity of language use – reflects a separate aspect of the bilingual experience from language-switching and language-mixing measures. The findings also indicate that language proficiency is not a uniform aspect of the bilingual experience but a complex construct that requires appropriately comprehensive measurements. Collectively, the findings contribute to the discussion on the best practices for quantifying bilingualism.

Research in bilingualism often involves quantifying constructs of interest by the use of rating scales: for example, to measure language proficiency, dominance, or sentence acceptability. However, ratings are a type of ordinal data, which violates the assumptions of the statistical methods that are commonly used to analyse them. As a result, the validity of ratings is compromised and the ensuing statistical inferences can be seriously distorted. In this article, we describe the problem in detail and demonstrate its pervasiveness in bilingualism research. We then provide examples of how bilingualism researchers can employ an appropriate solution using Bayesian ordinal models. These models respect the inherent discreteness of ratings, easily accommodate non-normality, and allow modelling unequal psychological distances between response categories. As a result, they can provide more valid, accurate, and informative inferences about graded constructs such as language proficiency. Data and code are publicly available in an OSF repository at https://osf.io/grs8x.

Studies examining the potential effects of bilingualism on interference suppression show inconsistent results. Our study approaches this topic by distinguishing two potential subcomponents within interference suppression (i.e., Stimulus-Stimulus and Stimulus-Response conflict). We investigated the two subcomponents through their operationalisation in different tasks and examined the role of language proficiency in modulating it. A sample of 111 young adult participants performed four non-linguistic cognitive tasks measuring both visual and auditory domains of cognitive control. Bilinguals outperformed monolinguals in tasks involving Stimulus-Stimulus conflict, but showed comparable performance in tasks involving Stimulus-Response conflict. Specific effects of language proficiency on cognitive control were observed: group differences in auditory inhibition and visual orienting were only observed between high-proficient bilinguals and monolinguals. Taken together, types of conflicts involved in interference tasks and language proficiency could differentially affect performance in monolinguals and bilinguals.

Twitter data from a crisis that impacted many English–Spanish bilinguals show that the direction of codeswitches is associated with the statistically documented tendency of single speakers to prefer one language over another in their tweets, as gleaned from their tweeting history. Further, lexical diversity, a measure of vocabulary richness derived from information-theoretic measures of uncertainty in communication, is greater in proximity to a codeswitch than in productions remote from a switch. The prospects of a role for lexical diversity in characterizing the conditions for a language switch suggest that communicative precision may induce conditions that attenuate constraints against language mixing.

Despite the multifactorial space of language experience in which people continuously vary, bilinguals are often dichotomized into ostensibly homogeneous groups. The timing of language exposure (age of acquisition) to a second language (L2) is one well-studied construct that is known to impact language processing, cognitive processing, and brain organization, but recent work shows that current language exposure is also a crucial determinant in these domains. Critically, many indices of bilingual experience are inherently subjective and based on self-report questionnaires. Such measures have been criticized in favor of objective measures of language ability (e.g., naming ability or verbal fluency). Here, we estimate the bilingual experience jointly as a function of multiple continuous aspects of experience, including the timing of language exposure, the amount of L2 exposure across communicative contexts, and language entropy (a flexible measure of language balance) across communicative contexts. The results suggest that current language exposure exhibits distinct but interrelated patterns depending on the socio-experiential context of language usage. They also suggest that, counterintuitively, our sample more accurately self-assesses L2 proficiency than native language proficiency. A precise quantification of the multidimensional nature of bilingualism will enhance the ability of future research to assess language processing, acquisition, and control.

The Cross-linguistic Lexical Task (CLT; Haman, Łuniewska & Pomiechowska, 2015) is a vocabulary task designed to enable cross-linguistic comparisons both across and within (bilingual) children. In this paper we assessed the validity of the CLT as a measure of language proficiency in bilingual children, by determining the extent to which (i) age-matched, monolingual Spanish-speaking and Dutch-speaking children obtained similar scores, (ii) the CLT correlated with other measures of language proficiency in monolingual and bilingual children, and (iii) whether the factors underlying the CLT's construction, i.e., target words’ estimated Age of Acquisition and Complexity Index, were predictive of children's scores. Our results showed that, while the CLT correlated with other measures and is therefore a valid means of tapping into language proficiency, caution is required when using it to compare children's language proficiency cross-linguistically, as scores for Dutch-speaking and Spanish-speaking monolinguals sometimes differed.

The study of bilingualism has a history that extends from deciphering ancient multilingual texts to mapping the structure of the multilingual brain. The language experiences of individual bilinguals are equally diverse and characterized by unique contexts of acquisition and use that can shape not only sociocultural identity but also cognitive and neural function. Perhaps unsurprisingly, this variability in scholarly perspectives and language experiences has given rise to a range of methods for defining bilingualism. The goal of this article is to initiate a conversation about the utility of a more unified approach to how we think about, study, and measure bilingualism. Using concrete case studies, we illustrate the value of enhancing communication and streamlining terminology across researchers with different methodologies within questions, different questions within domains, and different domains within scientific inquiry. We specifically consider the utility and feasibility of a bilingualism quotient (BQ) construct, discuss the idea of a BQ relative to the well-established intelligence quotient, and include recommendations for next steps. We conclude that though the variability in language backgrounds and approaches to defining bilingualism presents significant challenges, concerted efforts to systematize and synthesize research across the field may enable the construction of a valid and generalizable index of multilingual experience.