Early regular experience with dual-language management is thought to shape executive function (EF) circuitry during development. However, previous investigations of bilingual children's EF have largely focused on behavioral measures, or on cognitive aspects of EF. The first part of this study compared monolingual and bilingual preschoolers’ performance on more purely cognitive and more affective versions of a card-sort task, and the second part investigated Error-related negativity (ERN) event-related potential (ERP) waveforms to understand error-awareness mechanisms underlying task performance. Behavioral results showed bilingual advantages in reaction times but not accuracy, and interaction effects of language background, level of challenge, and affective/motivational salience on reaction times. Electrophysiological results revealed smaller ERN peak amplitudes in bilinguals compared to monolinguals in frontal and frontocentral midline regions. Results highlight that bilingualism may shape motivational mechanisms and neural learning mechanisms such as error-detection, such that bilinguals may be less focused on their errors.

Listeners are sensitive to speech sounds’ probability distributions. Distributional training (DT) studies with adults typically involve conscious activation of phoneme labels. We show that distributional exposure can shift existing phoneme boundaries (Spanish /e/–/i/) pre-attentively. Using a DT paradigm involving two bimodal distributions we assessed listener's neural discrimination across three sounds, showing pre-to-post-test improvement for the two adjacent sounds that fell into different clusters of the trained distribution than for those that fell into one cluster. Upon unattended exposure to an intricate stimulus set, listeners thus relocate native phoneme boundaries. We assessed whether the paradigm also works for category creation (Spanish establishing a duration contrast), where it has methodological advantages over the usual unimodal-versus-bimodal paradigm. DT yielded a greater effect for the /e/–/i/ boundary shift than for duration contrast creation. It seems that second-language phoneme contrasts similar to native ones might be easier to acquire than new contrasts.

Applied linguistic work claims that multilinguals’ non-native languages interfere with one another based on similarities in cognitive factors like proficiency or age of acquisition. Two experiments explored how trilinguals regulate control of native- and non-native-language words. Experiment 1 tested 46 Dutch–English–French trilinguals in a monitoring task. Participants decided if phonemes were present in the target language name of a picture, phonemes of non-target language translations resulted in longer response times and more false alarms compared to phonemes not present in any translation (Colomé, 2001). The second language (English) interfered more than the first (Dutch) when trilinguals monitored in their third language (French). In Experiment 2, 95 bilinguals learned an artificial language to explore the possibility that the language from which a bilingual learns a third language provides practice managing known-language interference. Language of instruction modulated results, suggesting that learning conditions may reduce interference effects previously attributed to cognitive factors.

This study examined intelligibility of twelve American English vowels produced by English, Chinese, and Korean native speakers in quiet and speech-shaped noise in which vowels were presented at six sensation levels from 0 dB to 10 dB. The slopes of vowel intelligibility functions and the processing time for listeners to identify vowels were dependent on speakers’ language backgrounds and non-native speakers’ vowel intelligibility in quiet. These results indicated that noise background affected non-native speakers’ vowel intelligibility more greatly than native speakers, possibly due to the acoustic deviations in non-native speech and lack of listeners’ experience to non-native produced speech.

Words’ morphemic structure and their orthographic representations vary across languages. How do bilingual experiences with structurally distinct languages influence children's morphological processes for word reading? Focusing on English literacy in monolinguals and bilinguals (N = 350, ages 5–9), we first revealed unique contributions of derivational (friend-li-est) and compound (girl-friend) morphology to early word reading. We then examined mechanisms of bilingual transfer in matched samples of Spanish–English and Chinese–English dual first language learners. Results revealed a principled cross-linguistic interaction between language group (Spanish vs. Chinese bilinguals) and type of morphological awareness. Specifically, bilinguals’ proficiency with the type of morphology that was less characteristic of their home language explained greater variance in their English literacy. These findings showcase the powerful effects of bilingualism on word reading processes in children who have similar reading proficiency but different language experiences, thereby advancing theoretical perspectives on literacy across diverse learners.

Language switching is often associated with language competition and switching costs. However, the underlying mechanisms might differ depending on context (free versus cued naming) and modality (production or comprehension). In this study, we assessed how response-stimulus intervals (RSI) influence language-switching costs. Longer RSIs might provide more time for interference from the previous trial to decay and result in smaller switching costs. Mandarin–English bilinguals completed two dual-language production tasks (Experiment 1: cued and voluntary picture naming) and one comprehension task (Experiment 2: animacy judgement) with a short RSI and a long RSI condition. While switching costs were present in all tasks, they were only influenced by RSI length in the cued-production task, with smaller switching costs in the long RSI condition. In contrast, RSI did not influence voluntary-production or comprehension costs. This suggests that bilinguals might apply language control differently to switch languages depending on the type of switching and modality.

Under the Interface Hypothesis, bilinguals’ non-nativelike referential choices may be influenced by the increased cognitive demands and less automatic processing of bilingual production. We test this hypothesis by comparing pronoun production in the L2 of nonbalanced Spanish–English bilinguals to that of English monolinguals in two cognitively challenging contexts. In Experiment 1, both monolinguals and bilinguals produced more explicit references when part of the information was unavailable to their addressee (privileged ground) than when all information was shared (common ground), evidencing audience design. In Experiment 2, verbal load led to more unspecified references than visual load and no load (an effect statistically indistinguishable between groups but numerically driven by the monolingual group). While bilinguals produced overall more pronouns than monolinguals in both experiments, there was no indication that bilinguals’ referential choice was disproportionally affected by increased cognitive demand, contrary to the predictions of the Interface Hypothesis.

The psycholinguistic literature suggests that the length of a to-be-spoken phrase impacts the scope of speech planning, as reflected by different patterns of speech onset latencies. However, it is unclear whether such findings extend to first and second language (L1, L2) speech planning. Here, the same bilingual adults produced multi-phrase numerical equations (i.e., with natural break points) and single-phrase numbers (without natural break points) in their L1 and L2. For single-phrase utterances, both L1 and L2 were affected by L2 exposure. For multi-phrase utterances, L1 scope of planning was similar to what has been previously reported for monolinguals; however, L2 scope of planning exhibited variable patterns as a function of individual differences in L2 exposure. Thus, the scope of planning among bilinguals varies as a function of the complexity of their utterances: specifically, by whether people are speaking in their L1 or L2, and bilingual language experience.

Most research showing that cognates are named faster than non-cognates has focused on isolated word production which might not realistically reflect cognitive demands in sentence production. Here, we explored whether cognates elicit interference by examining error rates during sentence production, and how this interference is resolved by language control mechanisms. Twenty highly proficient Spanish–English bilinguals described visual scenes with sentence structures ‘NP1-verb-NP2’ (NP = noun-phrase). Half the nouns and half the verbs were cognates and two manipulations created high control demands. Both situations that demanded higher inhibitory control pushed the cognate effect from facilitation towards interference. These findings suggest that cognates, similar to phonologically similar words within a language, can induce not only facilitation but robust interference.

Spanish–English bilinguals rarely code-switch in the perfect structure between the Spanish auxiliary haber (“to have”) and the participle (e.g., “Ella ha voted”; “She has voted”). However, they are somewhat likely to switch in the progressive structure between the Spanish auxiliary estar (“to be”) and the participle (“Ella está voting”; “She is voting”). This phenomenon is known as the “auxiliary phrase asymmetry”. One hypothesis as to why this occurs is that estar has more semantic weight as it also functions as an independent verb, whereas haber is almost exclusively used as an auxiliary verb. To test this hypothesis, we employed a connectionist model that produces spontaneous code-switches. Through simulation experiments, we showed that i) the asymmetry emerges in the model and that ii) the asymmetry disappears when using haber also as a main verb, which adds semantic weight. Therefore, the lack of semantic weight of haber may indeed cause the asymmetry.

Bilinguals engage in qualitatively different code-switching patterns (alternation, insertion, and congruent lexicalization) to different degrees, according to their engagement in different types of interactional contexts (single-language context, dual-language context, and dense code-switching context). Drawing on the adaptive control hypothesis, we examined whether bilinguals’ code-switching patterns would differentially shape multiple aspects of cognitive control (interference control, salient cue detection, and opportunistic planning). We found that a dense code-switching context, which predominantly involves insertion and congruent lexicalization, was positively associated with verbal opportunistic planning but negatively associated with interference control and salient cue detection. In contrast, a dual-language context, which predominantly involves alternation, was not associated with interference control or salient cue detection, but with significantly reduced response times for opportunistic planning. Our findings partially corroborate the theoretical predictions of the adaptive control hypothesis. Altogether, our study illustrates the importance of bilinguals’ disparate code-switching practices in shaping cognitive control outcomes.

Dutch–English participants named words and nonwords with a between-language phonologically inconsistent rime, e.g., GREED and PREED, and control words with a language-typical rime, e.g., GROAN, in a monolingual stimulus list or in a mixed list containing Dutch words. Inconsistent items had longer latencies and more errors than typical items in the mixed lists but not in the pure list. The consistency effect depended on word frequency, but not on language membership, lexicality, or instruction. Instruction did affect the relative speed and number of errors in the two languages. The consistency effect is the consequence of the simultaneous activation of two sublexical codes in the bilinguals' two languages and its size depends on the activation rate of the associated lexical representations (high-frequency words versus low-frequency words and nonwords) and on the decision criteria that monitor the response conflict at the decision level: the timing for responding (time criterion) in each language depends on the composition of the stimulus list and the likelihood of responses in either language.

This study investigated the influence of first language (L1) phoneme features and phonetic salience on discrimination of second language (L2) American English (AE) vowels. On a perceptual task, L2 adult learners of English with Spanish, Japanese or Russian as an L1 showed poorer discrimination of the spectral-only difference between /æ:/ as the oddball (deviant) among frequent /ɑ:/ stimuli compared to AE controls. The Spanish listeners showed a significant difference from the controls for the spectral-temporal contrast between /ɑ:/ and /ʌ/ for both perception and the neural Mismatch Negativity (MMN), but only for deviant /ɑ:/ versus /ʌ/ (duration decrement). For deviant /ʌ/ versus /ɑ:/, and for deviant /æ:/ versus /ʌ/ or /ɑ:/, all participants showed equivalent MMN amplitude. The asymmetrical pattern for /ɑ:/ and /ʌ/ suggested that L2 phonetic detail was maintained only for the deviant. These findings indicated that discrimination was more strongly influenced by L1 phonology than phonetic salience.

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.

Dijkstra and Van Heuven sketch the BIA+ model for visual word processing in bilinguals. BIA+ differs in a number of respects from its predecessor, BIA, the leading implemented model of bilingual visual word recognition. Notably, BIA+ contains a new processing component that deals with task demands. BIA+ has not been computationally implemented yet and design decisions still need to be taken. In this commentary, I outline a proposal for modeling the control of tasks in BIA+.

Mayberry and Kluender review evidence that second language (L2) proficiency declines with age of acquisition (regardless of modality), but they also review evidence for variable L2 outcomes for individuals, with factors such as motivation, language aptitude, education, and L2 experience playing a role. They argue that if L2 outcomes were fully under the control of a critical period for language (CPL), these learning variables should not predict L2 outcome, and the outcome of L2 learning would not be consistently observed to be so variable. The questions raised in this commentary are whether there is variation in late L1 proficiency and whether such variation could provide insights into the CPL.

This study aimed at identifying linguistic factors that could contribute to understanding individual differences in executive control among bilinguals. Directionality and type of natural language switching, age of second language acquisition, and language proficiency were evaluated in a sample of 112 early bilingual adults. Participants performed several computerized tasks tapping into three dimensions of executive control: inhibition of interference, working memory updating, and shifting. Regression analyses showed that frequent switching to the second language was associated with more efficient executive processing, enhanced working memory updating processes, and better shifting ability. Moreover, higher frequency of unintended language switches was associated with lower interference control abilities. Frequency of language switching behavior was the principal predictor of executive control, beyond age of second language acquisition and language proficiency. Results suggest that frequent language switching is related to enhanced executive control, while the unintended switching of languages could be associated with low interference control.

The phonological system of the French of Frenchville, Pennsylvania (USA) demonstrates a dramatic case of transfer in the latest (and last) generation of bilingual French–English speakers: the mid front round vowels, [œ] and [ø], have often been replaced by the English rhoticized schwa as found in the word sir. However, French schwa, which is arguably phonetically non-distinct from the mid front round vowels, does not participate fully in this merger. This result is unexpected given both the phonetic identity of schwa and [ø], and the fact that our speakers are not literate in French and, as such, have no access to the differential orthographic representations manifest between schwa and the mid front round vowels. The data argue strongly that schwa is, in some sense, “real” for these speakers. Based on a phonetic analysis of the vowels under consideration, we argue that transfer between two sound systems cannot be perceived as a simple case of phonetic replacement. Instead, transfer or convergence with English must be viewed as a systemic process that preserves contrast in unexpected ways. In the case at hand, the data suggest that the traditional separation between the phonetic and phonological levels of grammar cannot be maintained as each level contributes to both provoking merger and maintaining contrast in bilingual speech.