Relationship between language switching experience and executive functions in bilinguals: an Internet-based study*

We examined the relationship between self-reported everyday language switching experience and the performance of early bilinguals in tasks measuring different executive functions. Our participants were Finnish–Swedish early bilinguals, aged 16–41 years (N?=?66, Experiment 1) and 18–69 years (N?=?111, Experiment 2). An earlier study using a sample from a similar population discovered a negative relationship between self-reported language switching and a mixing cost in error rates in a number–letter task. This finding was not replicated. Instead, we found that a higher rate of reported contextual language switching predicted larger switching cost reaction times in the number–letter task, and that a higher rate of reported unintended language switches predicted larger error rates in a spatial n-back task. We conclude that these results likely reflect individual differences in executive skills, and do not provide evidence for the hypothesis that language switching trains executive functions.     

Dual language use in sign-speech bimodal bilinguals: fNIRS brain-imaging evidence

The brain basis of bilinguals’ ability to use two languages at the same time has been a hotly debated topic. On the one hand, behavioral research has suggested that bilingual dual language use involves complex and highly principled linguistic processes. On the other hand, brain-imaging research has revealed that bilingual language switching involves neural activations in brain areas dedicated to general executive functions not specific to language processing, such as general task maintenance. Here we address the involvement of language-specific versus cognitive-general brain mechanisms for bilingual language processing. We study a unique population, bimodal bilinguals proficient in signed and spoken languages, and we use an innovative brain-imaging technology, functional Near-Infrared Spectroscopy (fNIRS; Hitachi ETG-4000). Like fMRI, the fNIRS technology measures hemodynamic change, but it is also advanced in permitting movement for unconstrained speech and sign production. Participant groups included (i) hearing ASL–English bilinguals, (ii) ASL monolinguals, and (iii) English monolinguals. Imaging tasks included picture naming in “Monolingual mode” (using one language at a time) and in “Bilingual mode” (using both languages either simultaneously or in rapid alternation). Behavioral results revealed that accuracy was similar among groups and conditions. By contrast, neuroimaging results revealed that bilinguals in Bilingual mode showed greater signal intensity within posterior temporal regions (“Wernicke’s area”) than in Monolingual mode. Significance: Bilinguals’ ability to use two languages effortlessly and without confusion involves the use of language-specific posterior temporal brain regions. This research with both fNIRS and bimodal bilinguals sheds new light on the extent and variability of brain tissue that underlies language processing, and addresses the tantalizing questions of how language modality, sign and speech, impact language representation in the 7brain.     

Speech and language disturbances due to subcortical lesions

Over the last few decades, the number of studies concerning the role of subcortical structures in cognition has increased due to advances in neuroimaging. We describe the language and speech disturbances found in 16 patients with subcortical lesions (9 in basal ganglia and 7 in thalamus), evaluated by CT scan, MRI, and SPECT. Language assessment included the Boston Diagnostic Aphasia Examination, Boston Naming Test, and Token Test. Motor-articulatory alterations predominated in the non-thalamic group; in the thalamic group, there was a higher frequency of language alterations, especially in naming and auditory comprehension; verbal memory and attentional impairments may have contributed to this. We also found hypoperfusion in cortical language areas, and therefore participation of cortical dysfunction cannot be ruled out.     

Language learning and control in monolinguals and bilinguals

Parallel language activation in bilinguals leads to competition between languages. Experience managing this interference may aid novel language learning by improving the ability to suppress competition from known languages. To investigate the effect of bilingualism on the ability to control native-language interference, monolinguals and bilinguals were taught an artificial language designed to elicit between-language competition. Partial activation of interlingual competitors was assessed with eye-tracking and mouse-tracking during a word recognition task in the novel language. Eye-tracking results showed that monolinguals looked at competitors more than bilinguals, and for a longer duration of time. Mouse-tracking results showed that monolinguals' mouse movements were attracted to native-language competitors, whereas bilinguals overcame competitor interference by increasing the activation of target items. Results suggest that bilinguals manage cross-linguistic interference more effectively than monolinguals. We conclude that language interference can affect lexical retrieval, but bilingualism may reduce this interference by facilitating access to a newly learned language.     

A systematic review on the role of language-related factors in the manifestation of stuttering in bilinguals

PurposeBilingual(s) who stutter (BWS) provide an opportunity to explore the link between stuttering and language. Unlike in monolinguals, stuttering in bilinguals could be influenced by both speaker-related language (e.gs. dominance & proficiency) and linguistic typology-related factors (e.g., structure of languages). However, the available literature is largely inconclusive on these factors. In this context, we systematically reviewed the literature to compile evidence on the influence of such factors on BWS.MethodWe followed the conventional systematic review process that included five databases. Further, the quality of the included articles was assessed using Newcastle-Ottawa Scale (NOS) for quality rating.ResultThirteen articles passed the selection criteria. Review of these articles revealed that language proficiency and dominance are the important factors that affect stuttering frequency in BWS. Though the linguistic typology is portrayed as a factor on the differential manifestation of dysfluencies in both languages of the BWS, the literature does not provide substantiating data for this. Further, the lack of uniformity in assessing and reporting language dominance and proficiency are the major drawbacks in the existing literature on stuttering in BWS.ConclusionThis review identifies proficiency and dominance as the major factors that influence the stuttering frequency in BWS. Currently, the evidence for the influence of typological differences between languages of the BWS on stuttering largely remains whimsical. Future research shall employ the recommended tasks and metrics while assessing the dysfluencies in BWS so that findings across centres become comparable, which in turn, could yield valid inferences.     

Contributions of second language proficiency and interpreting experience to cognitive control differences among young adult bilinguals

The present study investigates how two important aspects of bilingualism, second language (L2) proficiency and language interpreting experience, contribute to cognitive control differences among young adult bilinguals. By requiring participants to complete the Flanker task (testing inhibition in cognitive control) and the Wisconsin Card Sorting Test (WCST; testing mental set shifting in cognitive control), we compared four groups of Chinese–English bilinguals who varied in L2 proficiency and interpreting experience. The results showed that there was no significant group difference across all groups in the Flanker task. However, in the WCST, although there was no group difference between bilinguals differing in L2 proficiency, there was a significant difference between groups differing in interpreting experience, including groups differing in years of interpreting training. The results indicate that language interpreting experience, as part of bilinguals' language use ecology, significantly contributes to mental set shifting enhancement in cognitive control among young adult bilinguals. The findings motivate further research into the processing mechanism involved in language interpreting.     

No compelling evidence for a bilingual advantage in switching or that frequent language switching reduces switch cost

Participants completed three cued-switching tasks, responded to two category-fluency probes, two letter-fluency probes, and two probes to alternate between two targets. Correlations across the three cued-switching tasks were significant for both switching costs and mixing costs. The bilingual advantage hypothesis was tested both by forming language groups and treating bilingualism as a continuous variable. No bilingual advantages were observed. In verbal-fluency monolinguals generated more correct responses but the bilingual disadvantage on the category task was not reduced in the letter-fluency scores. The bilingual disadvantage was eliminated when the groups were matched on vocabulary size. The verbal-fluency measures obtained when participants alternated between targets weakly correlated with the switching-costs obtained in the cued-switching tasks.     

Neural network processing of natural language: II. Towards a unified model of corticostriatal function in learning sentence comprehension and non-linguistic sequencing

A central issue in cognitive neuroscience today concerns how distributed neural networks in the brain that are used in language learning and processing can be involved in non-linguistic cognitive sequence learning. This issue is informed by a wealth of functional neurophysiology studies of sentence comprehension, along with a number of recent studies that examined the brain processes involved in learning non-linguistic sequences, or artificial grammar learning (AGL). The current research attempts to reconcile these data with several current neurophysiologically based models of sentence processing, through the specification of a neural network model whose architecture is constrained by the known cortico-striato-thalamo-cortical (CSTC) neuroanatomy of the human language system. The challenge is to develop simulation models that take into account constraints both from neuranatomical connectivity, and from functional imaging data, and that can actually learn and perform the same kind of language and artificial syntax tasks. In our proposed model, structural cues encoded in a recurrent cortical network in BA47 activate a CSTC circuit to modulate the flow of lexical semantic information from BA45 to an integrated representation of meaning at the sentence level in BA44/6. During language acquisition, corticostriatal plasticity is employed to allow closed class structure to drive thematic role assignment. From the AGL perspective, repetitive internal structure in the AGL strings is encoded in BA47, and activates the CSTC circuit to predict the next element in the sequence. Simulation results from Caplan's [Caplan, D., Baker, C., & Dehaut, F. (1985). Syntactic determinants of sentence comprehension in aphasia. Cognition, 21, 117-175] test of syntactic comprehension, and from Gomez and Schvaneveldts' [Gomez, R. L., & Schvaneveldt, R. W. (1994). What is learned from artificial grammars?. Transfer tests of simple association. Journal of Experimental Psychology: Learning, Memory and Cognition, 20, 396-410] artificial grammar learning experiments are presented. These results are discussed in the context of a brain architecture for learning grammatical structure for multiple natural languages, and non-linguistic sequences.     

The other modality: Auditory stimuli in language switching

Language switching studies typically implement visual stimuli and visual language cues to trigger a concept and a language response, respectively. In the present study we set out to generalise this to another stimulus modality by investigating language switching with auditory stimuli next to visual stimuli. The results showed that switch costs can be obtained with both auditory and visual stimuli. Yet, switch costs were relatively larger with visual stimuli than with auditory stimuli. Both methodological and theoretical implications of these findings are discussed.     

Non-selective lexical access in bilinguals is spontaneous and independent of input monitoring: Evidence from eye tracking

Language non-selective lexical access in bilinguals has been established mainly using tasks requiring explicit language processing. Here, we show that bilinguals activate native language translations even when words presented in their second language are incidentally processed in a nonverbal, visual search task. Chinese–English bilinguals searched for strings of circles or squares presented together with three English words (i.e., distracters) within a 4-item grid. In the experimental trials, all four locations were occupied by English words, including a critical word that phonologically overlapped with the Chinese word for circle or square when translated into Chinese. The eye-tracking results show that, in the experimental trials, bilinguals looked more frequently and longer at critical than control words, a pattern that was absent in English monolingual controls. We conclude that incidental word processing activates lexical representations of both languages of bilinguals, even when the task does not require explicit language processing.     

First and second language vowel perception in early bilinguals

Previous research has shown that the perception of speech sounds is strongly influenced by the internal structure of maternal language categories. Specifically, it has been shown that stimuli judged as good exemplars of a phonemic category are more difficult to discriminate from similar sounds than bad exemplars from equally similar sounds. This effect seems to be restricted to phonemes present in the maternal language, and is acquired in the first months of life. The present study investigates the malleability of speech acquisition by analysing the discrimination capacities for L2 phonemes in highly proficient Spanish-Catalan bilinguals born in monolingual families. In Experiment I subjects were required to give goodness of fit judgments to establish the best exemplars corresponding to three different vowel categories (Catalan /e/ and /ε/ Spanish /e/). In Experiments 2 and 3, bilinguals were asked to perform a discrimination task with materials in their maternal language (Exp. 2) and in their second language (Exp. 3). Results reveal that bilinguals show a reduced discrimination capacity only for good exemplars of their maternal language, but not for good exemplars of their second language. The same pattern of results was obtained in Experiment 4, using a within-subjects design and a bias-free discrimination measure (d'). These findings support the hypothesis that phonemic categories are not only acquired early in life, but under some circumstances, the acquisition of new phonemic categories can be seriously compromised, in spite of early and extensive exposure to L2.     

Independent effects of bilingualism and socioeconomic status on language ability and executive functioning

One hundred and seventy-five children who were 6-years old were assigned to one of four groups that differed in socioeconomic status (SES; working class or middle class) and language background (monolingual or bilingual). The children completed tests of nonverbal intelligence, language tests assessing receptive vocabulary and attention based on picture naming, and two tests of executive functioning. All children performed equivalently on the basic intelligence tests, but performance on the language and executive functioning tasks was influenced by both SES and bilingualism. Middle-class children outperformed working-class children on all measures, and bilingual children obtained lower scores than monolingual children on language tests but higher scores than monolingual children on the executive functioning tasks. There were no interactions with either group factors or task factors. Thus, each of SES and bilingualism contribute significantly and independently to children’s development irrespective of the child’s level on the other factor.     

Brain activations associated with sign production using word and picture inputs in deaf signers

Effective literacy education in deaf students calls for psycholinguistic research revealing the cognitive and neural mechanisms underlying their written language processing. When learning a written language, deaf students are often instructed to sign out printed text. The present fMRI study was intended to reveal the neural substrates associated with word signing by comparing it with picture signing. Native deaf signers were asked to overtly sign in Chinese Sign Language (CSL) common objects indicated with written words or presented as pictures. Except in left inferior frontal gyrus and inferior parietal lobule where word signing elicited greater activation than picture signing, the two tasks engaged a highly overlapping set of brain regions previously implicated in sign production. The results suggest that word signing in the deaf signers relies on meaning activation from printed visual forms, followed by similar production processes from meaning to signs as in picture signing. The present study also documents the basic brain activation pattern for sign production in CSL and supports the notion of a universal core neural network for sign production across different sign languages.     

Automatic perceptual simulation of first language meanings during second language sentence processing in bilinguals

Research supports the claim that, when understanding language, people perform mental simulation using those parts of the brain which support sensation, action, and emotion. A major criticism of the findings quoted as evidence for embodied simulation, however, is that they could be a result of conscious image generation strategies. Here we exploit the well-known fact that bilinguals routinely and automatically activate both their languages during comprehension to test whether this automatic process is, in turn, modulated by embodied simulatory processes. Dutch participants heard English sentences containing interlingual homophones and implying specific distance relations, and had to subsequently respond to pictures of objects matching or mismatching this implied distance. Participants were significantly slower to reject critical items when their perceptual features matched said distance relationship. These results suggest that bilinguals not only activate task-irrelevant meanings of interlingual homophones, but also automatically simulate these meanings in a detailed perceptual fashion. Our study supports the claim that embodied simulation is not due to participants' conscious strategies, but is an automatic component of meaning construction.     

The role of orthography in speech production revisited

The language production system of literate adults comprises an orthographic system (used during written language production) and a phonological system (used during spoken language production). Recent psycholinguistic research has investigated possible influences of the orthographic system on the phonological system. This research has produced contrastive results, with some studies showing effects of orthography in the course of normal speech production while others failing to show such effects. In this article, we review the available evidence and consider possible explanations for the discrepancy. We then report two form-preparation experiments which aimed at testing for the effects of orthography in spoken word-production. Our results provide clear evidence that the orthographic properties of the words do not influence their spoken production in picture naming. We discuss this finding in relation to psycholinguistic and neuropsychological investigations of the relationship between written and spoken word-production.     

Attentional control in early and later bilingual children

We examined differences in attentional control among school-age children who were monolingual English speakers, early Spanish-English bilinguals (who began speaking both languages by age 3), and later Spanish-English bilingual children (who began speaking English after age 3). Children's attentional control was tested using the Attention Network Test (ANT). All language groups performed equally on ANT networks; however, when controlling for age and verbal ability, groups differed significantly on reaction time. Early bilingual children responded faster on the ANT compared to both monolingual and later bilingual children, suggesting an attentional monitoring advantage for early bilinguals. These results add to evidence of advantaged cognitive functioning among bilinguals and are consistent with the possibility that children who begin speaking a second language earlier in childhood have greater advantages, due either to effects of acquiring a second language earlier or to longer duration of bilingual experience.     

On the time course of exogenous cueing effects in bilinguals: Higher proficiency in a second language is associated with more rapid endogenous disengagement

Previous investigations have demonstrated a bilingual advantage on various aspects of executive control. It remains unclear how the language proficiency of bilinguals might relate to the mechanisms involved in attentional disengagement. In the present investigation, we tested the hypothesis that high bilingual proficiency would lead to a more rapid endogenous disengagement of attention from task-irrelevant peripheral cues. We predicted that more rapid attentional disengagement would result in an earlier appearance of inhibition of return (IOR). In this study Hindi–English bilinguals who differed in their L2 (English) proficiency participated in a target detection task. Visual targets were preceded by uninformative peripheral cues at various stimulus onset asynchronies (SOAs) allowing for us to visualize the time course of cue-related facilitation and inhibition. High-proficient Hindi–English bilinguals showed an earlier appearance of IOR than did low-proficient bilinguals, suggesting increased efficiency in disengagement of attention from task-irrelevant inputs. Furthermore, consistent with the “global” advantage that characterizes bilinguals in many tasks, the high-proficient group outperformed low-proficient bilinguals in overall reaction time.     

The effects of late acquisition of L2 and the consequences of immigration on L1 for semantic and morpho-syntactic language aspects

It has been hypothesized that some aspects of a second language (L2) might be learned easier than others if a language is learned late. On the other hand, non-use might result in a loss of language skills in one's native, i.e. one's first language (L1) (language attrition). To study which, if any, aspects of language are affected by either late acquisition or non-use, long-term German immigrants to the US and English native speakers who are long-term immigrants to Germany as well as two additional control groups of native German speakers were tested with an auditory semantic and morpho-syntactic priming paradigm. German adjectives correctly or incorrectly inflected for gender and semantically associated or not associated with the target noun served as primes. Participants made a lexical decision on the target word. All groups of native German speakers gained from semantically and morpho-syntactically congruent primes. Evidence for language attrition was neither found for semantic nor morpho-syntactic priming effects in the German immigrants. In contrast, English native speakers did not gain from a morpho-syntactic congruent prime, whereas semantic priming effects were similar as for the remaining groups. The present data suggest that the full acquisition of at least some syntactic functions may be restricted to limited periods in life while semantic and morpho-syntactic functions seem to be relatively inured to loss due to non-use.