This study investigates Spanish heritage speakers' perception and production of Spanish lexical stress. Stress minimal pairs in various prosodic contexts were used to examine whether heritage speakers successfully identify the stress location despite varying suprasegmental cues (Experiment 1) and whether they use these cues in their production (Experiment 2). Heritage speakers' performance was compared to that of Spanish monolinguals and English L2 learners. In Experiment 1, the heritage speakers showed a clear advantage over the L2 learners and their performance was comparable to that of the monolinguals. In Experiment 2, both the heritage speakers and the L2 learners showed deviating patterns from the monolinguals; they produced a large overlap between paroxytones and oxytones, especially in duration. The discrepancy between heritage speakers' perception and production suggests that, while early exposure to heritage language is beneficial for the perception of heritage language speech sounds, this factor alone does not guarantee target-like production.

In bilinguals, language proficiency has been advanced to influence the involvement of domain-general control networks in language selection. We assessed, in university student translators with moderate- to high-second language (L2) proficiency depending on their translation educational level, the functional activity in the key language and control areas (the caudate nucleus, anterior cingulate, and prefrontal cortex), during task- and language-selection in an oral production context. We found that L2 proficiency influenced the relative involvement of our regions of interest during language selection vs domain-general cognitive control processes. While the left middle frontal and left caudate areas were more involved during linguistic than alphanumeric task selection in the low L2 proficiency group, these regions were similarly involved in both tasks in the high-L2 proficiency group. These findings suggest that language selection relies primarily on a network within domain-general cognitive control system with an increase in resource needs when L2 proficiency is low.

When bilinguals name pictures while in ‘monolingual mode’, we expect that under conditions of language-constraint and no cognate facilitation, factors influencing lexical retrieval in monolinguals ought to exert similar effects on bilinguals. To this end, we carried out a L1-only naming task on early Hindi–English bilinguals. Results of linear mixed effects analysis reveal AoA, Familiarity, Image Agreement and Codability (availability of alternate names) to be the most significant predictors of lexical retrieval speed for early bilinguals, confirming our expectations. However, we report, for the first time, a by-subject variation in Codability for bilinguals. Implications of the results are discussed in the context of current theories of bilingual lexical access and competition. In preparation for this study, Hindi norms from bilinguals for items in the Snodgrass and Vanderwart set have been established, which will be of use for stimuli selection in experimental studies involving bilinguals.

Heritage Spanish speakers and adult immigrant bilinguals listened to wh-questions with the differential object marker a (quién/a quién ‘who/whoACC’) while their eye movements across four referent pictures were tracked. The heritage speakers were less accurate than the adult immigrants in their verbal responses to the questions, leaving objects unmarked for case at a rate of 18%, but eye movement data suggested that the two groups were similar in their comprehension, with both starting to look at the target picture at the same point in the question and identifying the target sooner with a quién ‘whoACC’ than with quién ‘who’ questions.

Bilingual and multilingual individuals exhibit variation in everyday language experience. Studies on bilingualism account for individual differences with measures such as L2 age of acquisition, exposure, or language proficiency, but recent theoretical perspectives posit that the relative balance between the two or more languages throughout daily life (i.e., interactional context) is a crucial determinant for language representation, access, and control. We propose an innovative measure to characterize this construct by using entropy to estimate the social diversity of language use. Language entropy is computed from commonly-collected language history data and generalizes to multilingual communicative contexts. We show how language entropy relates to other indices of bilingual experience and that it predicts self-report L2 outcome measures over and above classic measures of language experience. Thus, we proffer language entropy as a means to characterize individual differences in bilingual (and multilingual) language experience related to the social diversity of language use.

This study investigates the psycholinguistic process underlying triggered codeswitching – codeswitching facilitated by the occurrence of cognates – within the context of conversational dynamics. It confirms that, in natural bilingual speech, lexical selection of cognates can facilitate codeswitching by enhancing the activation of the non-selected language. Analyses of a large-scale corpus of Welsh–English conversational speech showed that 1) producing cognates facilitated codeswitching, 2) speakers who generally produced more cognates generally codeswitched more, even in clauses that did not contain cognates, 3) larger numbers of cognates in a clause increased the likelihood of codeswitching, 4) codeswitching temporarily remained facilitated after the production of cognates, and 5) hearing rather than producing cognates did not facilitate codeswitching. The findings confirm the validity of the proposed cognitive account of triggered codeswitching, and clarify the relation between the lexical activation of cognates and consecutive language choice, in accord with current insights in lexical processing.

The putative bilingual executive advantage has been argued to stem from lifelong experience with executively demanding language behaviors, such as switching between the two languages. However, studies testing for possible associations between language switching frequency and EF in bilinguals have yielded inconsistent results. One reason for this could lie in the methods used that have evaluated the frequency and type of language switches with retrospective self-reports, as well as in problems in reliability and convergent validity of the executive tasks. By using Ecological Momentary Assessment (EMA) as a reference point for self-reports of language switches, we examined the validity of general retrospective self-reports of language switching. Additionally, we examined associations between language switching and EF using multilevel models. Our results indicated that the commonly used retrospective self-reports of language switching may lack convergent validity. However, we found tentative evidence that contextual language switches, assessed with EMA, may be associated with better inhibitory control, set shifting, and working memory.

We investigated how individual differences in language proficiency and executive control impact cross-language meaning activation through phonology. Ninety-six university students read English sentences that contained French target words. Target words were high- and low-frequency French interlingual homophones (i.e., words that share pronunciation, but not meaning across langauges; mot means ‘word’ in French and sounds like ‘mow’ in English) and matched French control words (e.g., mois – ‘month’ in French). Readers could use the homophones’ shared phonology to activate their English meanings and, ultimately, make sense of the sentence (e.g., Tony was too lazy to mot/mois the grass on Sunday). Shorter reading times were observed on interlingual homophones than control words, suggesting that phonological representations in one language activate cross-language semantic representations. Importantly, the magnitude of the effect was modulated by word frequency, and several participant-level characteristics, including French proficiency, English word knowledge, and executive control ability.

Matching participants (as suggested by Hope, 2015) may be one promising option for research on a potential bilingual advantage in executive functions (EF). In this study we first compared performances in three EF-tasks of a naturally heterogeneous sample of monolingual (n = 69, age = 9.0 y) and multilingual children (n = 57, age = 9.3 y). Secondly, we meticulously matched participants pairwise to obtain two highly homogeneous groups to rerun our analysis and investigate a potential bilingual advantage. The initally disadvantaged multilinguals (regarding socioeconomic status and German lexicon size) performed worse in updating and response inhibition, but similarly in interference inhibition. This indicates that superior EF compensate for the detrimental effects of the background variables. After matching children pairwise on age, gender, intelligence, socioeconomic status and German lexicon size, performances became similar except for interference inhibition. Here, an advantage for multilinguals in the form of globally reduced reaction times emerged, indicating a bilingual executive processing advantage.

A large sample study (n = 513) was conducted to investigate executive control performance in pupils following an immersion education program. We recruited 10-year-old children (n = 128) and 16-year-old adolescents (n = 127) who were enrolled in English or Dutch immersion education in French-speaking Belgium for at least 4 school years. They were compared to non-immersed children (n = 102) and adolescents (n = 156) on a number of executive control tasks assessing inhibitory control, monitoring, switching and attentional abilities. Several control variables such as receptive vocabulary, nonverbal intelligence, socioeconomic status and other potentially relevant background variables were also considered. Our results show significant gains in foreign-language proficiency for the immersed compared to the non-immersed participants. These gains were however not associated with any measurable benefits on executive control. Our findings make a unique contribution to understanding how language and cognition develop through formal education methods that promote bilingualism.

One hundred and seventy-two English-speaking 5- to 7-year-olds participated in a referential communication task where we manipulated the linguistic mention and the visual presence of a competitor alongside a target referent. Eighty-seven of the children were additionally exposed to a language other than English (bilinguals). We measured children's language proficiency, verbal working memory (WM), cognitive control skills, family SES, and relative amount of cumulative exposure and use of the home language for the bilinguals. Children's use of full Noun Phrases (NPs) to identify a target referent was predicted by the visual presence of a competitor more than by its linguistic mention. Verbal WM and proficiency predicted NP use, while cognitive control skills predicted both the ability to use expressions signalling discourse integration and sensitivity to the presence of a discourse competitor, but not of a visual competitor. Bilingual children were as informative as monolingual children once proficiency was controlled for.

Bilingualism has been said to improve cognition and even delay the onset of Alzheimer's disease (AD). This research aimed to investigate whether bilingualism leaves a neurophysiological trace even when people are highly educated. We expected bilinguals to present better preserved brain functional networks, which could be a trace of higher cognitive reserve. With this purpose, we conducted a magnetoencephalographic study with a group of healthy older adults. We estimated functional connectivity using phase-locking value and found five clusters in parieto-occipital regions in which bilinguals exhibited greater functional connectivity than monolinguals. These clusters included brain regions typically implicated in language processing. Furthermore, these functional changes correlated with caudate volumes (a key region in language shifting and control) in the bilingual sample. Interestingly, decreased Functional Connectivity between posterior brain regions had already been identified as an indicator of aging/preclinical AD but, according to our study, bilingualism seems to exert the opposite effect.

How bilinguals switch between languages depends on the context. In a voluntary context, bilinguals are free to decide when to switch, whereas in a cued context they are instructed when to switch. While using two languages may be more costly than using one in cued switching ('mixing cost'), recent evidence suggests that voluntarily using two languages may be less effortful than using one ('mixing benefit'). Direct comparisons between mandatory and voluntary switching, however, are needed to better understand the effects of the interactional context on bilingual language control. The current study compared mandatory and voluntary switching within the same task, thus keeping the overall task characteristics the same. We observed overall slower mandatory responses and larger mandatory than voluntary mixing and switching effects. Thus, using two languages is more costly in a mandatory than voluntary context, showing that the interactional context can affect the effort needed to control two languages.

This paper investigates whether there are changes in gesture rate when speakers of two languages with different gesture rates (Turkish-high gesture; Dutch-low gesture) come into daily contact. We analyzed gestures produced by second-generation heritage speakers of Turkish in the Netherlands in each language, comparing them to monolingual baselines. We did not find differences between bilingual and monolingual speakers, possibly because bilinguals were proficient in both languages and used them frequently – in line with a usage-based approach to language. However, bilinguals produced more deictic gestures than monolinguals in both Turkish and Dutch, which we interpret as a bilingual strategy. Deictic gestures may help organize discourse by placing entities in gesture space and help reduce the cognitive load associated with being bilingual, e.g., inhibition cost. Therefore, gesture rate does not necessarily change in contact situations but might be modulated by frequency of language use, proficiency, and cognitive factors related to being bilingual.

We examine whether early acquisition of a second language (L2) leads to native-like neural processing of phonemic contrasts that are absent in the L1. Four groups (adult and child monolingual speakers of English; adult and child early bilingual speakers of English and Spanish, exposed to both languages before 5 years of age) participated in a study comparing the English /ɪ/ - /ε/ contrast. Neural measures of automatic change detection (Mismatch Negativity, MMN) and attention (Processing Negativity, PN and Late Negativity, LN) were measured by varying whether participants tracked the stimulus stream or not. We observed no effect of bilingualism on the MMN, but adult bilinguals differed significantly from adult monolinguals on neural indices of attention. The child bilinguals were indistinguishable from their monolingual peers. This suggest that learning a L2 before five years of age leads to native-like phoneme discrimination, but bilinguals develop increased attentional sensitivity to speech sounds.

Much bilingualism research includes some consideration of codeswitching, which may be measured via self-report, an experimental task, or sociolinguistic interview; however, there is little triangulation across measures in either psycholinguistic or sociolinguistic approaches. To consider possible differences between self-report and oral production of codeswitching, Spanish–English bilinguals completed a codeswitching questionnaire and oral production in an autobiographical memory task. They also completed proficiency and executive function tests. We found that broad measures of self-reported and orally produced codeswitches were positively correlated, although relationships with proficiency and executive function were more complex. These findings may direct future studies’ operationalization of codeswitching.

Research on the effects of bi- and multi-lingualism on brain structure has so far yielded variable patterns. Although it cannot be disputed that learning and using additional languages restructures grey (cortical, subcortical and cerebellar) and white matter in the brain, both increases and reductions in regional volume and diffusivity have been reported. This paper revisits the available evidence from simultaneous and sequential bilinguals, multilinguals, interpreters, bimodal bilinguals, children, patients and healthy older adults from the perspective of experience-based neuroplasticity. The Dynamic Restructuring Model (DRM) is then presented: a three-stage model accounting for, and reinterpreting, all the available evidence by proposing a time-course for the reported structural adaptations, and by suggesting that these adaptations are dynamic and depend on the quantity and quality of the language learning and switching experience. This is followed by suggestions for future directions for the emerging field of bilingualism-induced neuroplasticity.