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.

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.

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.

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.

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.

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.

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.

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.