Bilinguals in a monolingual and a bilingual speech mode: The effect on lexical access

The time course of lexical access in fluent Portuguese-English bilinguals and in English speaking monolinguals was examined during the on-line processing of spoken sentences using the phoneme-triggered lexical decision task (Blank, 1980). The bilinguals were tested in two distinct speech modes: a monolingual, English or Portuguese, speech mode, and a bilingual, code-switching, speech mode. Although the bilingual’s lexical decision response times to word targets in the monolingual speech modes were identical to those of the monolingual subjects, their response times to code-switched word targets in the bilingual mode were significantly slower. In addition, the bilinguals took longer to detect nonwords in both the monolingual and bilingual modes. These results confirm that bilinguals cannot totally deactivate their other language when in a monolingual speech mode. It is hypothesized that bilinguals search both lexicons when confronted with nonwords, even when in a totally monolingual mode, and that they search the base-language lexicon before the other lexicon when in a bilingual, code-switching, speech mode.     

熟练汉-英双语者的语码切换机制—— 来自短语水平的证据

以熟练汉-英双语者为被试, 考察了在短语水平上语码切换的机制及切换代价的来源。结果表明：(1)汉语与英语表示空间方所的短语的差异和表示量的短语的对应与否影响语码切换过程, 但对于两种语言的切换代价的影响不显著, 表明语码切换代价未受特定语言的语法特征影响; (2)熟练汉-英双语者在短语水平上表现出语码切换代价的不对称性：切换至熟练语言的代价比切换至非熟练语言的代价大; (3)熟练汉-英双语者的切换代价源于两种语言短语的激活和竞争, 支持非特定语言选择假说, 可以用抑制控制模型来解释。整个研究表明, 熟练双语者的语码切换代价源于语言表征系统之外。     

Neural bases of language switching in high and early proficient bilinguals

The left inferior frontal cortex, the caudate and the anterior cingulate have been proposed as the neural origin of language switching, but most of the studies were conducted in low proficient bilinguals. In the present study, we investigated brain areas involved in language switching in a sample of 19 early, high-proficient Spanish–Catalan bilinguals using a picture naming task that allowed contrasting switch and non-switch trials. Compared to the non-switching condition, language switching elicited greater activation in the head of the left caudate and the pre-SMA/ACC. When the direction of the switching was considered, the left caudate was more associated with forward switching and the pre-SMA/ACC with backward switching. The discussion is focused on the relevance of these brain structures in language control in early, high-proficient bilinguals, and the comparison with previous results in late bilinguals.     

Bilingual toddlers’ comprehension of mixed sentences is asymmetrical across their two languages

In bilingual language environments, infants and toddlers listen to two separate languages during the same key years that monolingual children listen to just one and bilinguals rarely learn each of their two languages at the same rate. Learning to understand language requires them to cope with challenges not found in monolingual input, notably the use of two languages within the same utterance (e.g., Do you like the perro? or ¿Te gusta el doggy?). For bilinguals of all ages, switching between two languages can reduce the efficiency in real‐time language processing. But language switching is a dynamic phenomenon in bilingual environments, presenting the young learner with many junctures where comprehension can be derailed or even supported. In this study, we tested 20 Spanish–English bilingual toddlers (18‐ to 30‐months) who varied substantially in language dominance. Toddlers’ eye movements were monitored as they looked at familiar objects and listened to single‐language and mixed‐language sentences in both of their languages. We found asymmetrical switch costs when toddlers were tested in their dominant versus non‐dominant language, and critically, they benefited from hearing nouns produced in their dominant language, independent of switching. While bilingualism does present unique challenges, our results suggest a united picture of early monolingual and bilingual learning. Just like monolinguals, experience shapes bilingual toddlers’ word knowledge, and with more robust representations, toddlers are better able to recognize words in diverse sentences.     

汉-英和藏-汉-英双语者中、英文语码切换及代价研究

以汉—英和藏—汉—英双语者为被试,采用真假词判断范式,探讨中文和英文语码切换及代价。结果表明:(1)汉—英和藏—汉—英双语者中文语码切换代价不显著,英文语码切换代价显著;(2)汉—英和藏—汉—英双语者中、英文词加工差异显著,但语码切换趋势相同。这表明,加工方式和策略影响语言加工,不影响语码切换;语言熟练程度影响语码切换,两种语言的相对熟练程度决定切换代价的不对称性。     

双语者语言转换中非目标语言的加工机制

语言转换是指双语者由所掌握的一种语言转换到另一种语言的现象, 这一现象近些年来引起了研究者的广泛关注。针对语言转换中双语者在从心理词典中顺利提取所需要的语言(称之为目标语言)时如何加工在当前任务中不使用的那种语言(称之为非目标语言), 研究者进行了大量研究。仔细分析这些研究, 可以看出这些研究主要围绕着3个核心问题: (1)语言转换中双语者使用目标语言时非目标语言是否激活; (2)若非目标语言激活, 这种激活发生在何种层面(概念层面还是词汇层面); (3)激活的非目标语言会对目标语言产生什么样的影响。以此为基础, 本文从语言产生转换和语言理解转换两大领域对相关研究进行了总结和梳理, 最后对未来的语言转换研究进行了展望。     

语言转换的认知及其神经机制

语言转换是双语研究领域的焦点问题之一,抑制控制模型、语言特异性选择模型、任务设置惯性模型和序列难度效应模型从不同的角度解释了语言转换的认知机制。认知神经科学的一些研究发现,语言转换与任务转换具有类似的神经机制,说明语言转换代价与任务转换代价的本质可能是相同的。抑制控制和语言熟练程度如何影响语言的转换,语言转换代价与任务转换代价的本质是否相同,一般领域的抑制机制是否可以迁移到语言转换领域等问题是未来需要进一步研究的问题。     

Language switching in the bilingual brain: What’s next?

Recent work using functional neuroimaging with early bilinguals has found little evidence for separate neural systems for each language during picture naming (Hernandez, A. E., Dapretto, M., Mazziotta, J., & Bookheimer, S. (2001). Language switching and language representation in Spanish–English bilinguals: An fMRI study. Neuroimage, 14, 510–520). However, switching between languages in early bilinguals during picture naming shows increased activity in the Dorsolateral Prefrontal Cortex (DLPFC) suggesting the importance of maintaining goal related information in order to bias subsequent response selection (Braver, T. S., Barch, D. M., Kelley, W. M., Buckner, R. L., Cohen, N. J., Miezin, F. M., et al. (2001). Direct comparison of prefrontal cortex regions engaged by working and long-term memory tasks. Neuroimage, 14, 48–59; Cohen, J. D., Braver, T. S., & O’Reilly, R. C. (1996). A computational approach to prefrontal cortex, cognitive control and schizophrenia: Recent developments and current challenges. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences, 351, 1515–1527; O’Reilly, R. C., Braver, T. S., & Cohen, J. D. (1999). A biologically based computational model of working memory. In E. Akira Miyake, E. Priti Shah & et al. (Eds.), Models of working memory: Mechanisms of active maintenance and executive control. (pp. 375–411): New York, NY, USA). The current study set out to test early bilinguals using a picture naming paradigm. Results revealed increased activity in the DLPFC and the superior parietal lobule during language switching compared to naming of pictures in a single language. Increased activity was also observed between early learned first and second languages. The results from single language conditions revealed differences in areas devoted to language processing such as the Superior Temporal Gyrus. However, increased activity in brain areas devoted to memory, somatosensory processing and emotion were also observed. Taken together these results replicate previous studies on language switching. They also extend studies on the neural bases of bilingualism by suggesting that early bilinguals’ representation of the two languages may be mediated by neural systems not typically associated with language. The article ends by considering future directions in understanding the brain bases of language switching and single language processing in bilinguals.     

In Search of the Language Switch: An fMRI Study of Picture Naming in Spanish–English Bilinguals

For many years, researchers investigating the brain bases of bilingualism have concentrated on two basic questions. The first concerns the nature of language representation. That is, are a bilinguals' two languages represented in distinct or overlapping areas of the brain. The second basic question in the neuropsychology of bilingualism concerns the neural correlates of language switching, that is, the areas that are active when bilinguals switch from one language to the other. Performance between single-language and dual-language picture naming was compared in a group of six Spanish–English bilinguals using behavioral measures and functional magnetic resonance imaging. Participants showed slower reaction times and increased activation in the dorsolateral prefrontal cortex in the mixed language condition relative to single language condition. There was no evidence that each language was represented in different areas of the brain. Results are consistent with the view that language switching is a part of a general executive attentional system and that languages are represented in overlapping areas of the brain in early bilinguals.     

双语者代码切换的认知与神经机制——从行为研究到脑成像研究

双语者代码切换的机制已引起心理语言学家和认知神经科学家的广泛关注。研究分别在行为层面和神经机制层面展开。发现,双语者在进行代码切换时会出现切换代价,切换代价来源于心理词典外部的语言任务图式之间的竞争,其机制可能与中央执行控制机制有密切联系,左侧额下回、双侧缘上回和背外侧前额叶等脑区参与了双语者的代码切换过程。文章还分析了在这一领域仍待研究的一些问题,并提出了进一步开展双语代码切换研究的建议。     

口译员的认知转换优势

口译可视为一种强化的双语转换活动。与一般双语者相比, 口译员在基于规则(rule-based)的转换与基于任务(task-based)的转换两方面都表现出了优势, 但基于任务的转换优势存在局部转换与整体监控的争议。经初步探索, 口译训练首先带来局部转换优势(单价任务的转换代价), 随后带来整体监控优势(双价任务的混合代价)。口译涉及的高强度语言转换及特殊的语言控制特性可能是影响口译员认知转换优势的因素。上述结果对双语优势及其他相关研究有启示作用。     

Effects of speed of word processing on semantic access: the case of bilingualism

Bilingual speakers generally manifest slower word recognition than monolinguals. We investigated the consequences of the word processing speed on semantic access in bilinguals. The paradigm involved a stream of English words and pseudowords presented in succession at a constant rate. English-Welsh bilinguals and English monolinguals were asked to count the number of letters in pseudowords and actively disregard words. They were not explicitly told that pairs of words in immediate succession were embedded and could either be semantically related or not. We expected that slower word processing in bilinguals would result in semantic access indexed by semantic priming. As expected, bilinguals showed significant semantic priming, indexed by an N400 modulation, whilst monolinguals did not. Moreover, bilinguals were slower in performing the task. The results suggest that bilinguals cannot discriminate between pseudowords and words without accessing semantic information whereas monolinguals can dismiss English words on the basis of subsemantic information.     

In search of the language switch: An fMRI study of picture naming in Spanish-English bilinguals

For many years, researchers investigating the brain bases of bilingualism have concentrated on two basic questions. The first concerns the nature of language representation. That is, are a bilinguals' two languages represented in distinct or overlapping areas of the brain. The second basic question in the neuropsychology of bilingualism concerns the neural correlates of language switching, that is, the areas that are active when bilinguals switch from one language to the other. Performance between single-language and dual-language picture naming was compared in a group of six Spanish-English bilinguals using behavioral measures and functional magnetic resonance imaging. Participants showed slower reaction times and increased activation in the dorsolateral prefrontal cortex in the mixed language condition relative to single language condition. There was no evidence that each language was represented in different areas of the brain. Results are consistent with the view that language switching is a part of a general executive attentional system and that languages are represented in overlapping areas of the brain in early bilinguals.     

认知灵活性对非熟练双语者语言转换的影响--一项ERPs研究*

采用 WCST 筛选出高低认知灵活性的非熟练汉英双语者,分别使用图片命名和语义范畴判断任务考察认知灵活性对双语者语言转换的影响。结果发现：(1)高认知灵活性被试的双语转换代价是对称的,其N2成分的平均波幅和峰值显著大于低认知灵活性被试,低认知灵活性被试的转换代价是非对称的;(2)高认知灵活性被试在语言产生任务中, L2重复条件下N2的峰值显著大于L1重复条件,出现L2重复优势效应;(3)在语言理解任务中,高低认知灵活性被试在L1重复条件下的N2峰值显著大于L2重复条件,两组均出现了L1重复优势效应。研究表明,抑制控制能力在语言产生与理解的双语转换中起着重要的作用,语言转换代价源于心理词典的字词识别系统之外。     

Musical Training,Bilingualism, and Executive Function: A Closer Look at Task Switching and Dual‐Task Performance

This study investigated whether musical training and bilingualism are associated with enhancements in specific components of executive function, namely, task switching and dual‐task performance. Participants (n = 153) belonging to one of four groups (monolingual musician, bilingual musician, bilingual non‐musician, or monolingual non‐musician) were matched on age and socioeconomic status and administered task switching and dual‐task paradigms. Results demonstrated reduced global and local switch costs in musicians compared with non‐musicians, suggesting that musical training can contribute to increased efficiency in the ability to shift flexibly between mental sets. On dual‐task performance, musicians also outperformed non‐musicians. There was neither a cognitive advantage for bilinguals relative to monolinguals, nor an interaction between music and language to suggest additive effects of both types of experience. These findings demonstrate that long‐term musical training is associated with improvements in task switching and dual‐task performance.     

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.     

语言转换对非熟练双语者不同认知控制成分的即时影响

语言转换情境是否影响非熟练双语者的认知控制存在争议。实验1和实验2分别采用不同的实验范式探讨语言转换对非熟练双语者的认知控制是否会有即时的影响, 以及对不同认知控制成分的影响是否会有不同。结果表明, 语言转换情境能够即时地促进反应抑制, 阻碍干扰抑制, 但对认知灵活性没有影响, 同时说明了反应抑制、干扰抑制和认知灵活性属于3种不同的认知成分, 其内在作用机制不同。此外, 研究结果还进一步说明了双语者的认知控制优势是双语者长期双语使用的结果, 为双语优势的内在机制提供了实验支持。     

Cognates interfere with language selection but enhance monitoring in connected speech

The current study investigated the contribution of phonology to bilingual language control in connected speech. Speech production was elicited by asking Mandarin–English bilinguals to read aloud paragraphs either in Chinese or English, while six words were switched to the other language in each paragraph. The switch words were either cognates or noncognates, and switching difficulty was measured by production of cross-language intrusion errors on the switch words (e.g., mistakenly saying 巧克力 (qiao3-ke4-li4) instead of chocolate). All the bilinguals were Mandarin-dominant, but produced more intrusion errors when target words were written in Chinese than when written in English (i.e., they exhibited robust reversed dominance effects). Most critically, bilinguals produced significantly more intrusions on Chinese cognates, but also detected and self-corrected these same errors more quickly than with noncognates. Phonological overlap boosts dual-language activation thus leading to greater competition between languages, and increased response conflict, thereby increasing production of intrusions but also facilitating error detection during speech monitoring.     

Morphological priming survives a language switch

In a long-lag morphological priming experiment, Dutch (L1)-English (L2) bilinguals were asked to name pictures and read aloud words. A design using non-switch blocks, consisting solely of Dutch stimuli, and switch-blocks, consisting of Dutch primes and targets with intervening English trials, was administered. Target picture naming was facilitated by morphologically related primes in both non-switch and switch blocks with equal magnitude. These results contrast some assumptions of sustained reactive inhibition models. However, models that do not assume bilinguals having to reactively suppress all activation of the non-target language can account for these data.