This longitudinal study examined the cognitive development of Spanish children from monolingual backgrounds attending schools with varying levels of English exposure (13%–83%) to assess whether higher L2 exposure results in advantages over time. 229 children (ages 6–7) completed background (nonverbal reasoning (NVR), working memory (WM), L1 vocabulary, L2 vocabulary) and experimental tests measuring attentional/executive functions (selective attention, divided attention, switching, inhibition) at the beginning and end of year 1 of primary education. Generalized linear mixed-effects models, accounting for factors such as family educational level, onset of L2 exposure and language exposure outside of school, indicated that children’s cognitive skills benefit from (high) L2 exposure at school, with greater L2 exposure being linked to more enhanced attentional/executive skills as well as to a larger L2 vocabulary. These findings support the positive effects of immersion programs, suggesting that L2 exposure in school settings alone can contribute to more developed attentional/executive skills.

We corroborate findings showing a disparity in one’s willingness to update political beliefs in the face of counterevidence among bilinguals, examining the role of the Foreign Language effect (FLe) on belief maintenance. 133 Liberal English-Spanish bilinguals and 70 English monolinguals showed that belief change on political issues is lesser than on nonpolitical issues following counterevidence. Bilinguals, however, showed greater change in the second language (L2) compared to the first and greater belief change than the monolinguals overall. The second language also led to slower reading and rating times across all conditions, which corresponded with greater belief change. Among bilinguals using their L2, those most likely to show belief change reported having a less meaningful connection to the foreign language.

Most people are multilingual, and most multilinguals code-switch, yet the characteristics of code-switched language are not fully understood. We developed a chatbot capable of completing a Map Task with human participants using code-switched Spanish and English. In two experiments, we prompted the bot to code-switch according to different strategies, examining (1) the feasibility of such experiments for investigating bilingual language use and (2) whether participants would be sensitive to variations in discourse and grammatical patterns. Participants generally enjoyed code-switching with our bot as long as it produced predictable code-switching behavior; when code-switching was random or ungrammatical (as when producing unattested incongruent mixed-language noun phrases, such as ‘la fork’), participants enjoyed the task less and were less successful at completing it. These results underscore the potential downsides of deploying insufficiently developed multilingual language technology, while also illustrating the promise of such technology for conducting research on bilingual language use.

Bilinguals simultaneously activate both languages during word retrieval. False cognates, words overlapping in form but not meaning across languages, typically trigger crosslinguistic interference relative to non-cognates. Crosslinguistic interference resolution can be impaired in bilinguals with stroke-induced aphasia, yet little is known about the neural dynamics supporting these interference resolution processes. We recorded scalp electroencephalography in 21 age-matched controls and five bilinguals with aphasia participating in a picture-word interference paradigm eliciting crosslinguistic interference and a nonlinguistic spatial Stroop task. Bilinguals with aphasia showed lower performance than age-matched controls and crosslinguistic interference was present across both groups. A medial frontal component peaking around 400 ms post stimulus presentation was present in controls across tasks but was absent in the linguistic task in bilinguals with aphasia. This suggests that while bilinguals typically engage the medial frontal cortex to resolve crosslinguistic interference, this mechanism is disrupted in bilinguals with aphasia.

Individuals differ in a range of processes related to reading comprehension, including working memory capacity, decoding skills, inference making and main idea identification. In this exploratory study, we examined evoked potential N400 amplitude during reading comprehension tasks and focused on identifying the main idea in the text, modulated by working memory capacity. Participants included monolinguals or bilinguals who were either typical readers (n = 33) or had been diagnosed with dyslexia (n = 19). Analyses revealed significant group differences for main idea conditions. Participants with dyslexia showed greater N400 amplitude than typical readers, particularly in the right hemisphere, when the main idea was in the last position in the paragraph. There were no significant differences in performance between bilinguals and monolinguals, which does not support the idea of a cognitive advantage for bilingualism. It was noteworthy that, if they had dyslexia, they were similarly negatively impacted by their reading disability. Findings highlight the processing advantages typical readers have relative to dyslexia.

This study investigated the hypothesis that 9- to 11-month-old multilingual infants learning Advanced Tongue Root (ATR) harmony languages (such as Akan) alongside other non-vowel harmony languages in Ghana (Africa) can use ATR harmony cues for speech segmentation. Using the central fixation procedure, infants were familiarized with bisyllabic words in two passages, one with ATR cues and one without, and then tested on isolated familiarized and novel bisyllabic words. Results indicate that, as a group, infants segmented words in their native language using ATR harmony cues, showing a familiarity preference. No effect of exposure to ATR harmony language(s) was found. These results provide the first evidence of word segmentation in infants learning between two and five languages, and with infants in Africa. The findings contribute to our understanding of multilingual infants’ language processing, suggesting their sensitivity to phonotactic cues for speech processing.

How does bilingualism affect orthographic processing across languages with different structures? This study investigates masked transposed-letter (TL) priming in Arabic-English bilinguals, comparing Arabic (a Semitic language with rigid orthography and weak TL effects) with English (an Indo-European language with flexible letter coding and strong TL effects). Using lexical decision tasks, we tested whether exposure to English enhances letter-coding flexibility in Arabic. Results showed robust TL priming in both languages, indicating that bilingual experience with English modifies Arabic orthographic processing, traditionally seen as resistant to letter transpositions. These findings suggest that bilingual orthographic processing is adaptable, with language-specific exposure reshaping letter-position encoding and enabling flexible word recognition across languages.

What is the optimal level of questionnaire detail required to measure bilingual language experience? This empirical evaluation compares alternative measures of language exposure of varying cost (i.e., questionnaire detail) in terms of their performance as predictors of oral language outcomes. The alternative measures were derived from Q-BEx questionnaire data collected from a diverse sample of 121 heritage bilinguals (5–9 years of age) growing up in France, the Netherlands and the UK. Outcome data consisted of morphosyntax and vocabulary measures (in the societal language) and parental estimates of oral proficiency (in the heritage language). Statistical modelling exploited information-theoretic and cross-validation approaches to identify the optimal language exposure measure. Optimal cost–benefit was achieved with cumulative exposure (for the societal language) and current exposure in the home (for the heritage language). The greatest level of questionnaire detail did not yield more reliable predictors of language outcomes.

Older adults commonly experience declines in cognitive control, which significantly impacts their well-being. Although intensive language training, particularly interpreting, holds potential for mitigating these declines, its efficacy remains largely unexplored. Based on previous findings in the literature (especially our theoretical framework on interpreting), we designed a 24-hour programme of Between-Dialect Interpreting Training (BIT). Using a pretest-intervention-posttest design, we evaluated the efficacy of the BIT (over 8 weeks) against a control group on general cognitive ability (MoCA) and core cognitive control functions – working memory (via listening span and digit backward tasks), interference control (via Stroop and Flanker tasks) and cognitive flexibility (via colour-shape task and WCST). Results demonstrated notable between-group differences favouring the BIT, with significant improvements in listening span, Stroop effect and Stroop global RT, colour-shape switch cost and marginal improvements in digit backward score and MoCA. The implications of how language training promotes cognitive health during ageing are discussed.

Although bilinguals use both auditory and visual cues, the cognitive cost of language switching in audiovisual contexts is unclear. We investigated the cost in Tibetan–Chinese bilinguals using a task with audiovisual, visual and auditory modalities. In Study 1, the audiovisual modality yielded the fastest reaction times, reflecting improved processing efficiency. ERP data revealed smaller positive amplitudes in the early window (200–350 ms) for audiovisual modality, indicating reduced neural demand, while only auditory modality showed significant divergence in the later window (350–700 ms). Moreover, audiovisual context, L2-to-L1 switching and early neural responses predicted switching behavior. Study 2 replicated the behavioral and ERP findings of Study 1 and demonstrated that auditory input and second-language processing exacerbated switch costs. These findings shed light on multisensory integration in language switching by demonstrating that audiovisual cues reduce switch costs, whereas auditory input and second-language processing exacerbate them, with implications for language education and cognitive interventions.

We investigate timing and eye-movement behavior during semantic prediction in L1 and L2 speakers of English using the Visual World Paradigm, additionally exploring speech rate. We differentiate first-stage predictions, considered to be automatic and relatively cost-free, from second-stage predictions, which are non-automatic and more cognitively demanding, with differences between L1 and L2 speakers believed to arise in second-stage predictions. We found no differences in the divergence of looks to the target in first- or second-stage predictions across groups. However, speech rate played an important role. Both L1 and L2 speakers showed similar first-stage predictions at slower speech rates, but L1 speakers showed earlier predictions as the speech rate increased. L2 speakers showed reduced and more variable second-stage predictions, suggesting they were impacted during the more demanding second-stage prediction. This may indicate a wait-and-see strategy to help reduce costs associated with second-stage prediction.

Previous research using cued language switching paradigms has shown a reversed language dominance effect in highly proficient bilinguals, wherein the dominant language is most inhibited. This study investigated cued language switching in highly proficient Spanish–Basque bilinguals (N = 50) using pupillometry, a novel measure of switching cost that tracks cognitive load via pupil size. Response times during cued picture-naming showed faster responses on non-switch than switch trials and faster responses in Basque than in Spanish. These findings suggest balanced proficiency across languages, with Spanish showing overall slowed responses, indicating a reversed dominance effect. Pupil data revealed larger pupil responses for Basque, the less dominant language, suggesting greater cognitive load despite faster naming. This indicates more attentional allocation or activation of the non-dominant language during cued language switching. These results provide insights into the cognitive processes involved in bilingual switching and highlight the value of using pupillometry to explore bilingual language processing.

This longitudinal study investigates the development and interrelation of adolescent learners’ L2 English vocabulary knowledge and extramural English (EE) input. The study examines the longitudinal development of L2 English receptive vocabulary knowledge, EE input and the dynamics between L2 proficiency and EE input. Data were collected at four time points by administering vocabulary tests and questionnaires on EE activities. Generalized additive mixed models and growth curve models indicated significant vocabulary growth, particularly in the early years of secondary school, which slowed down toward the end of the study. EE activities such as gaming, social media and reading positively predicted vocabulary development, while watching television with L1 subtitles had a negative effect. Temporal network analysis revealed reciprocal relationships, suggesting that L2 proficiency influences EE input and vice versa. The findings underscore the importance of EE in L2 vocabulary development and highlight the dynamic interplay between language learning and extramural activities.

Whether bilingualism confers non-linguistic cognitive advantages continues to generate both interest and debate in the psychological sciences. In response to mixed reports and methodological critiques, researchers have embraced more rigorous practices when investigating bilingual effects, including those in the domain of cognitive control. Despite considerable advances, one significant issue persists: the assumption that task performance remains stable over time. To address this, the present study investigated the relationship between bilingual language experience and Simon task performance modeled as a continuous function of time. In a sample of Mandarin-English bilingual young adults, we identified distinct patterns of results across both conventional and time-sensitive performance trajectory measures with each supporting a different relationship between language experience and cognitive control. Results suggest that reliance on conventional performance measures may be partially responsible for mixed results, necessitating reevaluation of how bilingual effects on cognitive control manifest and which analysis methods best support their identification.

Embodied cognition theory posits that language comprehension is grounded in sensorimotor experience. For instance, abstract concepts such as perceived power are metaphorically associated with spatial information such as physical size. Here, using a size judgement task, we investigated whether perceived power embodiment differs between languages in Chinese–English bilinguals. Asked to make judgements regarding the physical size of words, participants responded faster and made fewer errors to high-power words (e.g., king) presented in bold and large font than in thin and small font, while no such effect was found for low-power words. Furthermore, this congruency effect was stronger in bilinguals’ L1 (Chinese) than in their L2 (English). Thus, while embodiment of perceived power is detectable in both languages of bilinguals, it appears weaker in the L2. This study highlights cross-linguistic similarities and differences in the embodiment of abstract concepts and contributes to our understanding of conceptual knowledge grounding in bilinguals.

Learning to map novel words onto their intended referents is a complex challenge, and one that becomes even harder when acquiring multiple languages. We investigated how label mixing affected learning novel words in one versus two languages. In a cross-situational word learning study, 80 adult participants learned either one-to-one word–object mappings, or two-to-one mappings, reflecting different challenges in learning one or two languages. We manipulated whether mappings co-occurred locally, where repetitions were prevalent, or whether co-occurrences were more distributed throughout exposure. Learners acquired two-to-one mappings better when they did not occur in local co-occurrences, but there was no effect of learning conditions for one-to-one mappings. Whether participants were proficient or not in an additional language did not have an observable effect on the learning. We suggest that local co-occurrences of multiple labels, as in language mixing environments, increase the challenge of learning words, though this effect may be only short-lived.

We tested masked morphological priming effects with prefixed and suffixed words in L2 speakers of German with L1 Turkish, a language in which prefixes are virtually absent. We found weaker prefixation than suffixation priming, suggesting that cross-linguistic morphological differences between speakers’ L1 and L2 may influence L2 morphological processing. We additionally compared our findings to those of a previous study involving L1 Russian-L2 German speakers and L1 German speakers (Ciaccio & Clahsen (2020). Variability and consistency in first and second language processing: A masked morphological priming study on prefixation and suffixation. Language Learning, 70(1), 103–136). The magnitude of prefixation versus suffixation priming of our group was significantly larger than that reported for the L1 Russian-L2 German group, further corroborating the cross-linguistic hypothesis. However, we found no significant difference between our group and L1 German speakers. Therefore, we additionally consider the hypothesis of a general processing disadvantage for prefixed words as an alternative explanation. We conclude that several factors may contribute to why prefixation, in some studies, proves to be more challenging than suffixation, cross-linguistic influences being possibly just one of them.

We explored the relationships between L2 utterance fluency and cognitive fluency in monologic and dialogic tasks. The study involved 136 Chinese university-level English learners. Utterance fluency was measured through speed, breakdown, and repair fluency aspects. Cognitive fluency was indicated by L2 lexical and syntactic processing efficiency measures. Stepwise regression models, including metrics of L2-specific cognitive fluency, L2 knowledge, and L1 utterance fluency as predictors, targeted L2 utterance fluency as the dependent variable. We found that L2 cognitive fluency predicted limited variance in utterance fluency, with its influence more evident in monologues. L2 lexical processing efficiency paralleled syntactic processing efficiency’s importance in the monologic task but surpassed it in dialogues. Moreover, L2 processing speed had a more significant impact on utterance fluency than processing stability across both contexts. We suggest that cognitive fluency is not the sole determinant of utterance fluency; L2 knowledge and L1 utterance fluency play non-negligible roles.

It has been argued that under certain conditions bilingualism can confer adaptations to the human mind and brain. Among the possible moderators of such adaptations, language distance occupies a distinctly ambiguous role. Equally unclear is the directionality of the effect, as juggling different languages may become more or less cognitively costly depending on how (dis)similar competing alternatives are. If different language pairings entail that a different degree of cognitive effort is needed to manage bilingualism, language distance asymmetries are predicted to differentially contribute to the robustness of bilingual adaptations. In this systematic review and Bayesian analysis, we find strong evidence for a distance effect in bilingualism, but mixed evidence concerning its directionality in terms of being more pronounced in similar versus distant languages. We chart the extreme variability that exists across studies, highlighting the need for developing ecologically accepted metrics of what counts as similar in language processing.

We examined how language affects moral judgments in a non-WEIRD population. Tanzanian participants (N = 103) evaluated utilitarian agents in moral dilemmas, either in native Chagga or foreign Swahili. Agents were rated significantly more moral and braver when evaluated in a foreign language. Bravery predicted morality more strongly in the foreign language than in the native language. Indirect sacrifices were judged more moral than direct ones, but equally brave. These findings extend the moral foreign language effect to informally acquired languages and highlight methodological implications for cross-cultural research.