A long-standing question about bilingualism concerns which representations are shared across languages. Recent work has revealed a bilingual Sentence Superiority Effect (SSE) among French–English bilinguals reading mixed-language sentences: identification of target words is more accurate in syntactically grammatical than ungrammatical sentences. While this ability to connect words across the two languages has been attributed to a rapid parsing of shared syntactic representations, outstanding questions remain about the role of semantics. Here, we replicate the SSE in Spanish–English bilinguals (e.g., better identification of vacío in “my vaso is vacío” [my glass is empty] than “is vaso my vacío” [is glass my empty]). Importantly, we report evidence that semantics do contribute to word identification, but significantly less than syntax and only in the context of syntactically grammatical sentences. Moreover, the effect is moderated by language proficiency, further constraining the conditions under which shared cross-linguistic representations are rapidly accessed in the bilingual mind.

Cross-linguistic structural priming effects suggest that bilinguals have shared or connected memory representations for similar syntactic structures. This predicts an influence of the production preferences of one language in the other language (Bernolet & Hartsuiker, 2018). We hypothesized that shared structures will lead to a facilitatory effect on production frequencies, whereas connected structures may sometimes lead to an inhibitory effect due to competition between structures. We compared the production preferences and priming effects in Dutch for the frequent by-phrase-final and the uncommon by-phrase-medial passive between Arabic/Berber–Dutch and Turkish–Dutch heritage speakers and native speakers of Dutch. Arabic/Berber–Dutch speakers produced more agentless passives –that is, the alternative shared between their two languages. In contrast, Turkish–Dutch speakers produced less by-phrase-medial passives, although these are less uncommon in Turkish. This inhibition effect suggests that syntactic structures may sometimes be connected rather than shared, although the exact mechanisms behind the inhibitory effects require further research.

Correctly spelling an English word requires a high-quality orthographic representation. When faced with spelling a complex word without a high-quality representation, spellers often rely on other knowledge sources (e.g., incomplete stored orthographic forms, phonological to orthographic relationships) to spell it. For bilinguals, another potentially facilitative source is knowledge of a word's lexical and sublexical representations in another language. In the current study we considered simultaneous effects of word-level (e.g., frequency, cognate status) and person-level (e.g., English spelling skill, prompting, bilingual status) predictors on college students’ complex English word spelling. Monolinguals (English; n = 42) significantly outperformed bilinguals (Spanish and English; n = 76) on non-cognate spelling; no group differences emerged for cognate spelling accuracy. Within bilinguals, significantly higher spelling performance on cognates compared to non-cognates suggests cognate facilitation, with no prompting effects. Findings expand an interdisciplinary framework of understanding bilinguals’ activation and use of cross-linguistic representations in spelling.

Whereas growing evidence supports the advantages of bilingualism for brain structure and function, no study has shown multilingual-related neuroplasticity in response to speech stimuli at the subcortical level. To investigate the impact of multilingualism on subcortical auditory processing, the speech auditory evoked response (speech-ABR) was recorded on 35 young adults. The multilingual group completed the language experience and proficiency questionnaire (LEAP-Q). The results were that multilingual participants demonstrated evidence of enhanced neural timing processing, including a shorter wave D latency and the V-A duration, and a sharper V-A slope compared to the monolinguals in silence. In the noise condition, the speech-ABR measures degraded in most components, and no significant difference was observed between the two groups. The association between the total proficiency score and several subcortical responses was significant. This shows subcortical evidence of stronger neural synchronization in multilinguals relative to monolinguals, correlated with the self-report of multilingual experience.

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 aim of our study was to examine the longitudinal associations between two forms of second language (L2) knowledge (i.e., explicit and implicit knowledge) and the activity types that facilitate different processing mechanisms (i.e., form- and meaning-focused processing). L2 English speakers completed two tests of explicit knowledge (untimed written grammaticality judgment test and metalinguistic knowledge test) and three tests of implicit knowledge (timed written grammaticality judgment test, oral production, and elicited imitation) at the beginning and the end of a semester of university-level study. To track engagement in the activity types, participants completed self-reported language exposure logs across five days throughout the semester. The results from an autoregressive cross-lag analysis suggest L2 explicit and implicit knowledge influenced each other reciprocally over time. Neither activity type predicted knowledge development. We conclude that language acquisition is a developmental process typified by a dynamic, synergistic interface between explicit and implicit knowledge.

Effective communication in multilingual environments requires bilinguals to constantly monitor linguistic cues. It is hypothesized that the constant need to monitor may result in improved attention. However, previous investigations have reported mixed, often null results, with positive findings attributed to non-linguistic variables. To address these issues, we investigated whether higher levels of bilingualism were associated with improved attentional function in a sample of culturally and socioeconomically homogenous Mandarin–English speaking bilingual adolescents. Participants completed the Attention Network Task to assess attentional network function. Data were analyzed using linear mixed-effects models in order to account for nontrivial differences. Mixed results provide partial support for domain general cognitive benefits associated with higher levels of bilingualism. Both improved and reduced performance differed based on the specific dimension of bilingualism and the attentional network assessed. Findings support the conclusion that separable dimensions of bilingual language experience assert different influences on attentional network function.

This study investigates child heritage speakers’ Spanish direct objects. A task designed to elicit direct objects was completed in Spanish and English by 40 child heritage speakers of Spanish in the U.S., and in Spanish by 24 monolingual children in Mexico. Both participant groups varied their direct object forms, following the same ranking: clitics>lexical NPs>omission>doubling. Animate referents promoted clitics; inanimate referents promoted lexical NPs. Among the heritage speakers, more Spanish experience and Spanish lexical proficiency predicted more clitic use (less omission and lexical NP use). We also argue that the child heritage speakers’ production of strong pronouns, more lexical NPs, and masculine clitic lo with inanimate feminine referents suggest English influence. The study underscores the importance of examining structured variation, which revealed both similarities and differences between heritage and monolingual speakers.

Since globalization, using second languages (L2) to make decisions about future is more common than ever. In this study, we tested the merged effect of two language features, i.e., the future-time reference (FTR) and L2, on intertemporal decision and its indirect mediators, future orientation, and subjective future perception. As a pair of languages with different FTR, English (strong-FTR) has a clear grammatical separation between present and future, while Chinese (weak-FTR) does not. Here, Chinese first language (L1) speakers made intertemporal decisions using either Chinese (L1) or English (L2). Across three studies (N = 1022) and an internal meta-analysis, we found that using a strong-FTR L2 did not change participants’ intertemporal preference but did reduce their future orientation. These findings highlight a holistic perspective merging language features, outcome variables and measurement methods. These findings also imply a need for caution to use second language as nudge strategy in intertemporal decision-making.

Second language learners’ reading is less efficient and more effortful than native reading. However, the source of their difficulty is unclear; L2 readers might struggle with reading in a different orthography, or they might have difficulty with later stages of linguistic interpretation of the input, or both. The present study explored the source of L2 reading difficulty by analyzing the distribution of fixation durations in reading. In three studies, we observed that L2 readers experience an increase in Mu, which we interpret as indicating early orthographic processing difficulty, when the L2 has a significantly different writing system than the L1 (e.g., Chinese and English) but not when the writing systems were similar (e.g., Portuguese and English). L2 readers also experienced an increase in Tau, indicating later-arising processing difficulty which likely reflects later-stage linguistic processes, when they read for comprehension. L2 readers of Chinese also experienced an additional increase in Tau.

The performance of cognitive tests is highly dependent on the proficiency of the language in which the tests are administered. Not all Indonesians speak Indonesian daily and many are bilingual. We investigate whether language(s) spoken affects the performance on three language tests in 840 participants ranging in age (16–80) and education (6–22 years). Analysis of covariance followed by Helmert contrasts showed a disadvantage on the Boston Naming Test (BNT) and on the most difficult items of the Token Test for those who do not speak Bahasa daily. Bilinguals did worse on the BNT. Education had a large positive effect on the language tests, age a smaller negative effect. This suggests that besides age and education, the factor of language spoken, either in public or at home, needs to be taken into account when a participant's test scores on the BNT and TT are interpreted and compared with normative data.

Researchers have taken great interest in the assessment of text readability. This study expands on this research by developing readability models that predict the processing effort involved during first language (L1) and second language (L2) text reading. Employing natural language processing tools, the study focused on assessing complex linguistic features of texts, and these features were used to explain the variance in processing effort, as evidenced by eye movement data for L1 or L2 readers of English that were extracted from an open eye-tracking corpus. Results indicated that regression models using the indices of complex linguistic features provided better performance in predicting processing effort for both L1 and L2 reading than the models using simple linguistic features (word and sentence length). Furthermore, many of the predictive variables were lexical features for both L1 and L2 reading, emphasizing the importance of decoding for fluent reading regardless of the language used.

Referential processing relies on similar cognitive functions across languages – in particular, working memory. However, this has only been investigated in spoken languages with highly similar referential systems. In contrast to spoken languages, American Sign Language (ASL) uses a spatial referential system. It is unknown whether the referential system of ASL (L1) impacts referential processing in English (L2). This cross-language impact may be of particular importance for deaf, bimodal bilinguals who sign in ASL and read in English. Self-paced reading times of pronouns in English texts were compared between ASL–English bimodal bilinguals and Chinese–English unimodal bilinguals. The results showed that L1 referential characteristics influenced pronoun reading time in L2. Furthermore, in contrast to Chinese–English bilinguals, ASL–English bilinguals’ referential processing during reading of English texts relied on vocabulary knowledge – not working memory. These findings emphasize the need to expand current theories of referential processing to include more diverse types of language transfer.

An episodic memory experiment was conducted to examine whether “conceptual metaphors” influence how metaphorical expressions are processed and encoded into memory. Forty Chinese–English bilinguals read lists of expressions in their L1 and L2. The data revealed that after reading a series of metaphorical expressions based on the same underlying conceptual metaphor, participants falsely recognized new sentences that instantiated the same conceptual metaphor mapping more often than control sentences that did not share this mapping. This false memory effect was robust in both participants’ L1 and L2, with the only difference between languages being that participants showed more memory errors for literal sentences related to the source domain of the conceptual metaphors when reading in their second language (i.e., English). These data suggest that although bilinguals can access the appropriate conceptual metaphors in their second language, they have difficulty inhibiting literal meaning when processing metaphorical statements.

Titone and Tiv's Systems Theory of Bilingualism aims to “urge cognitive scientists and neuroscientists to better embrace sociolinguistic and sociocultural experiences as part of their theoretical and empirical purview”. No stronger case for such a framework can be found than in studies of developmental aspects of bilingualism. In fact, inclusion of sociocultural variation has been a common feature of many studies of dual language learning for some time, especially in studies of pre-school and early-school-age learners (see Genesee, 2019, for a review). Young dual language learners – neonates, infants and toddlers, exposed to more than one language – begin life as virtual tabula rasa and are capable of learning any language with facility. As a result, their language acquisition is necessarily tied to the sociocultural parameters of the learning environments they are exposed to. Moreover, as Titone and Tiv emphasize, the immediate and ultimate purpose of language learning is communication. Thus, young dual language learners must be attuned to and acquire the sociocultural constraints and norms for communicating effectively in more than one language. While sociocultural variation is important for understanding language acquisition even among monolingual children living in relatively homogeneous monocultural environments, sociocultural variation is inherent and, indeed, enhanced in the learning environments of children acquiring more than one language insofar as each language is intimately linked with different socio-cultural parameters. Sociocultural variation can be important for understanding bilingualism in yet another way. In studies of the neuro-cognitive consequences of bilingualism, it has been reported that there is a more pronounced association between dual language exposure and activation of certain brain areas among adolescent bilinguals from relatively low SES backgrounds than bilinguals from relatively high SES backgrounds (Brito & Noble, 2018). Inclusion of sociocultural variation in research on the effects of bilingualism can reveal a more nuanced view than emerges if such variation is not considered.

Bilingual and monolingual children might have different styles of using multimodal language. This study investigates speech disfluency and gesture production of 5- and 7-year-old Turkish monolingual (N = 61) and Turkish–English bilingual children (N = 51). We examined monolinguals’ Turkish narratives and bilinguals’ Turkish and English narratives. Results indicated that bilinguals were more disfluent than monolinguals, particularly for silent and filled (e.g., umm) pauses. Bilinguals used silent pauses and repetitions (e.g., cat cat) more frequently in English than in Turkish. Gesture use was comparable across language and age groups, except for iconic gestures. Monolinguals produced more iconic gestures than bilinguals. Children's overall gesture frequency predicted disfluency rates only in Turkish. Different gesture types might be orchestrated in the multimodal system, contributing to narrative fluency. The use of disfluency and gesture types might provide insight into bilingual and monolingual children's language development and communication strategies.

Despite a meteoric rise, results in the cognitive science of bilingualism present with significant inconsistency. In parallel, there is a striking absence of an ecologically valid theory within bilingualism research. How should one interpret the totality of available data that can pull in opposing directions? To proceed, we need to identify which practices impede progression. Hitherto, we bring to the fore an undiscussed practice, contextualizing how it impacts the ability to embed the available results into an overarching theory. We suggest that a stacking the deck fallacy – the tendency to engage differently with available evidence, directing focus to specific sub-samples – hampers theory formation. We put forth a proposal for making progress, building on the premise that what is lacking in the field is a unifying perspective that reconciles seemingly contradictory results. We suggest that the necessary shift of perspective towards progress crucially entails linking the notions of spectrum and trade-off.