Developmental associations between bilingual experience and inhibitory control trajectories in Head Start children

Children from lower socioeconomic (SES) backgrounds tend to be at‐risk for executive function (EF) impairments by the time they are in preschool, placing them at an early disadvantage for academic success. The present study examined the potentially protective role of bilingual experience on the development of inhibitory control (IC) in 1146 Head Start preschoolers who were followed for an 18‐month period during the transition to kindergarten as part of the longitudinal Family and Child Experiences Survey (FACES) 2009 study. Using three waves of data, we predicted individual variation in developmental trajectories of IC for three groups that differed in bilingual experience—English monolinguals, Spanish‐English bilinguals, and a group of children who transitioned from being Spanish monolingual to Spanish‐English bilinguals during the course of the study. Compared to their English monolingual peers, bilingual children from Spanish‐speaking homes showed higher IC performance at Head Start entry, as well as steeper IC growth over time. Children who were Spanish monolingual at the beginning of Head Start showed the lowest IC performance at baseline. However, their rate of IC growth exceeded that of children who remained English monolingual and did not differ from that of their peers who entered Head Start being bilingual. These results suggest that acquiring bilingualism and continued bilingual experience are associated with more rapid IC development during the transition from preschool to kindergarten in children from lower SES backgrounds.     

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.     

Effect of language proficiency and executive control on verbal fluency performance in bilinguals

We use a time-course analysis to examine the roles of vocabulary size and executive control in bilinguals’ verbal fluency performance. Two groups of bilinguals and a group of monolingual adults were tested in English with verbal fluency subtests from the Delis–Kaplan Executive Function System. The two bilingual groups were equivalent in their self-rated English proficiency but differed in levels of receptive and expressive vocabulary. We hypothesized that the difference between the two bilingual groups in vocabulary and between the monolingual and bilingual groups in executive control would lead to differences in performance on the category and letter fluency tests and dissociate the roles of vocabulary knowledge and executive control in verbal production. Bilinguals and monolinguals performed equivalently in category fluency, but the high-vocabulary bilingual group outperformed both monolinguals and low-vocabulary bilinguals in letter fluency. An analysis of the retrieval time-course functions in letter fluency showed dissociable effects of resources available at the initiation of the trial, considered to reflect vocabulary size, and ability to monitor and retrieve new items using a novel phonemic-based word searching strategy, considered to reflect executive control. The difference in slope of the best-fitting curves reflected enhanced executive control for both bilingual groups compared to monolinguals, whereas the difference in the starting point of the logarithmic functions reflected higher levels of vocabulary for high-vocabulary bilinguals and monolinguals compared to low-vocabulary bilinguals. The results are discussed in terms of the contributions of linguistic resources and executive control to verbal performance.     

Language proficiency and executive control in proactive interference: evidence from monolingual and bilingual children and adults

Two studies are reported in which monolingual and bilingual children (Study 1) and adults (Study 2) completed a memory task involving proactive interference. In both cases, the bilinguals attained lower scores on a vocabulary test than monolinguals but performed the same on the proactive interference task. For the children, bilinguals made fewer intrusions from previous lists even though they recalled the same number of words. For the adults, bilinguals recalled more words than monolinguals when the scores were corrected for differences in vocabulary. In addition, there was a strong effect of vocabulary in which higher vocabulary participants recalled more words irrespective of language group. These results point to the important role of vocabulary in verbal performance and memory. They also suggest that bilinguals may compensate for weaker language proficiency with their greater executive control to achieve the same or better levels of performance as monolinguals.     

Disentangling Context Availability and Concreteness in Lexical Decision and W ord Translation

This study examines contrasting predictions of the dual coding theory and the context availability hypothesis regarding concreteness effects in monolingual and bilingual lexical processing. In three experiments, concreteness was controlled for or confounded with rated context availability. In the first experiment, bilingual subjects performed lexical decision in their native language (Dutch, L1). In the second experiment, lexical decision performance of bilinguals in their second language (English, L2) was examined. In the third experiment, bilinguals translated words 'forwards' (from L1 to L2) or 'backwards' (from L2 to L1). Both monolingual and bilingual tasks showed a concreteness effect when concreteness was confounded with context availability. However, concreteness effects disappeared when abstract and concrete words were matched on context availability, and even occasionally reversed. Implications of these results for theories that account for concreteness effects, particulary in bilingual processing, are discussed.     

The perception of stop consonant voicing by Spanish-English bilinguals

The performance of Spanish-English bilinguals in two perception tasks, using a synthetic speech continuum varying in voice onset time, was compared with the performance of Spanish and English monolinguals. Voice onset time in speech production was also compared between these groups. Results in perception of bilinguals differed from that of both monolingual groups. Results of bilingual production in their two languages conformed with results obtained from each monolingual group. The perceptual results are interpreted in terms of differences in the use of available acoustic cues by bilingual and monolingual listeners of English and Spanish.     

The first steps in word learning are easier when the shoes fit: comparing monolingual and bilingual infants

English, French, and bilingual English-French 17-month-old infants were compared for their performance on a word learning task using the Switch task. Object names presented a /b/ vs. /g/ contrast that is phonemic in both English and French, and auditory strings comprised English and French pronunciations by an adult bilingual. Infants were habituated to two novel objects labeled 'bowce' or 'gowce' and were then presented with a switch trial where a familiar word and familiar object were paired in a novel combination, and a same trial with a familiar word–object pairing. Bilingual infants looked significantly longer to switch vs. same trials, but English and French monolinguals did not, suggesting that bilingual infants can learn word–object associations when the phonetic conditions favor their input. Monolingual infants likely failed because the bilingual mode of presentation increased phonetic variability and did not match their real-world input. Experiment 2 tested this hypothesis by presenting monolingual infants with nonce word tokens restricted to native language pronunciations. Monolinguals succeeded in this case. Experiment 3 revealed that the presence of unfamiliar pronunciations in Experiment 2, rather than a reduction in overall phonetic variability was the key factor to success, as French infants failed when tested with English pronunciations of the nonce words. Thus phonetic variability impacts how infants perform in the switch task in ways that contribute to differences in monolingual and bilingual performance. Moreover, both monolinguals and bilinguals are developing adaptive speech processing skills that are specific to the language(s) they are learning.     

The bilingual L2 advantage in recognition memory

To better understand the mechanisms by which bilingual proficiency impacts memory processes, two recognition memory experiments were conducted with matched monolingual and bilingual samples. In Experiment 1, monolingual speakers of English and Spanish studied high- and low-frequency words under full attention or cognitive load conditions. In Experiment 2, Spanish–English bilingual participants studied high- and low-frequency words under full-attention conditions in each language. For both monolinguals and bilinguals, low-frequency words were better recognized than high-frequency words. The central new findings were that bilingual recognition was more accurate in the less fluent language (L2) than in the more fluent language (L1) and that bilingual L2 recognition was more accurate than monolingual recognition. The bilingual L2 advantage parallels word frequency effects in recognition and is attributed to the greater episodic distinctiveness of L2 words, relative to L1 words.     

A bilingual advantage in visual language discrimination in infancy

The origins of the bilingual advantage in various cognitive tasks are largely unknown. We tested the hypothesis that bilinguals' early capacities to track their native languages separately and learn about the properties of each may be at the origin of such differences. Spanish-Catalan bilingual and Spanish or Catalan monolingual infants watched silent video recordings of French-English bilingual speakers and were tested on their ability to discern when the language changed from French to English or vice versa. The infants' performance was compared with that of previously tested French-English bilingual and English monolingual infants. Although all groups of monolingual infants failed to detect the change between English and French, both groups of bilingual infants succeeded. These findings reveal that bilingual experience can modulate the attentional system even without explicit training or feedback. They provide a basis for explaining the ontogeny of the general cognitive advantages of bilinguals.     

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.     

Phonological memory in bilinguals and monolinguals

In the present study, we examined the effects of lexical-semantic knowledge and of difficulty level on phonological memory performance by monolingual adult English speakers and bilingual adult Korean?CEnglish speakers. The monolingual English speakers were more proficient in English than the bilingual speakers. All participants were tested on a range of phonological memory tasks in English. We manipulated the degree to which the phonological memory tasks involved lexical-semantic knowledge of English (word-span task, digit-span task, and nonword repetition task), as well as the difficulty level of the tasks. Results revealed that on the word-span task (highest level of lexical-semantic knowledge), monolinguals outperformed bilinguals at the easier levels of the task but bilinguals outperformed monolinguals at the more difficult levels of the task. For the digit-span and nonword repetition tasks, monolinguals outperformed bilinguals at the easier levels of the tasks, but the differences between the two groups vanished with the increase in the difficulty levels. Together, these results suggest that proficiency-based differences between monolingual and bilingual phonological memory performance depend on the degree to which the tasks rely on lexical-semantic knowledge and the difficulty level of the task.     

On the Functional Equivalence of Monolinguals and Bilinguals in "Monolingual Mode": The Bilingual Anticipation Effect in Picture-Word Processing

Previous evidence indicates that bilinguals are slowed when an unexpected language switch occurs when they are reading aloud. This anticipation effect was investigated using a picture-word translation task to compare English monolinguals and Spanish-English bilinguals functioning in "monolingual mode." Monolinguals and half of the bilinguals drew pictures or wrote English words for picture or English word stimuli; the remaining bilinguals drew pictures or wrote Spanish words for picture or Spanish word stimuli. Production onset latency was longer in cross-modality translation than within-modality copying, and the increments were equivalent between groups across stimulus and production modalities. Assessed within participants, bilinguals were slower than monolinguals under intermixed but not under blocked trial conditions. Results indicate that the bilingual anticipation effect is not specific to language-mixing tasks. More generally, stimulus-processing uncertainty prevents establishment of a "base" symbolic-system procedure (concerning recognition, production, and intervening translation) and the inhibition of others. When this uncertainty is removed, bilinguals exhibit functional equivalence to monolinguals.     

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.     

Visual field asymmetries for rhyme and syntactic category judgments in monolinguals and fluent early and late bilinguals

A tachistoscopic study investigated hemispheric specialization among monolingual and fluent French-English bilingual adults for speeded rhyme and syntactic category matching. A right visual field superiority was obtained for both types of verbal judgments. This effect was more pronounced in late bilinguals than in early bilinguals or monolinguals. In addition, bilingual subgroup differences in response latency and strategy were found, suggesting a preference for semantic processing among early bilinguals and for surface processing among late bilinguals, consistent with previous findings. Possible theoretical implications of these differences are outlined.     

Language-experience facilitates discrimination of /d-th/ in monolingual and bilingual acquisition of English

To trace how age and language experience shape the discrimination of native and non-native phonetic contrasts, we compared 4-year-olds learning either English or French or both and simultaneous bilingual adults on their ability to discriminate the English /d-th/ contrast. Findings show that the ability to discriminate the native English contrast improved with age. However, in the absence of experience with this contrast, discrimination of French children and adults remained unchanged during development. Furthermore, although simultaneous bilingual and monolingual English adults were comparable, children exposed to both English and French were poorer at discriminating this contrast when compared to monolingual English-learning 4-year-olds. Thus, language experience facilitates perception of the English /d-th/ contrast and this facilitation occurs later in development when English and French are acquired simultaneously. The difference between bilingual and monolingual acquisition has implications for language organization in children with simultaneous exposure.     

Bilinguals’ twisted tongues: Frequency lag or interference?

Though bilinguals know many more words than monolinguals, within each language bilinguals exhibit some processing disadvantages, extending to sublexical processes specifying the sound structure of words (Gollan & Goldrick, Cognition, 125(3), 491–497, 2012). This study investigated the source of this bilingual disadvantage. Spanish–English bilinguals, Mandarin–English bilinguals, and English monolinguals repeated tongue twisters composed of English nonwords. Twister materials were made up of sound sequences that are unique to the English language (nonoverlapping) or sound sequences that are highly similar—yet phonetically distinct—in the two languages for the bilingual groups (overlapping). If bilingual disadvantages in tongue-twister production result from competition between phonetic representations in their two languages, bilinguals should have more difficulty selecting an intended target when similar sounds are activated in the overlapping sound sequences. Alternatively, if bilingual disadvantages reflect the relatively reduced frequency of use of sound sequences, bilinguals should have greater difficulty in the nonoverlapping condition (as the elements of such sound sequences are limited to a single language). Consistent with the frequency-lag account, but not the competition account, both Spanish–English and Mandarin–English bilinguals were disadvantaged in tongue-twister production only when producing twisters with nonoverlapping sound sequences. Thus, the bilingual disadvantage in tongue-twister production likely reflects reduced frequency of use of sound sequences specific to each language.     

Language and Cognitive Predictors of Lexical Selection in Storytelling for Monolingual and Sequential Bilingual Children

The primary purpose of the present study was to test language and cognitive predictors of lexical selection in the storytelling of monolingual and bilingual children. Measures of language proficiency and cognitive ability were assessed with both English- and Mandarin-speaking monolinguals and Mandarin-English bilinguals aged 4 to 6 years old. To elicit stories, children watched a cartoon and told the story back. Bilinguals did these tasks in both of their languages. The results showed that the bilinguals told stories with as many different words as monolinguals of both languages but scored lower on measures of vocabulary. For monolinguals, vocabulary score was an important predictor of lexical variety even after controlling for age. For bilinguals, attentional control was a significant predictor of lexical variety in their second language, English. These results suggest that for monolingual children, vocabulary size is an important predictor of lexical variety in stories, while bilingual children might rely more on cognitive abilities to lexicalize concepts.     

The effects of phonological awareness of Zulu‐speaking children learning to spell in English: A study of cross‐language transfer

Background. Emergent bilingual Zulu–English speaking children in South Africa have spoken but no written proficiency in Zulu (L1), yet are required to learn to spell English (L2) via English‐only literacy instruction. Little research exists on emergent bilingual's phonological awareness (PA) and spelling development, with no L1 formal literacy instruction. Thus, whether PA in a L1 impacts on literacy acquisition in the L2 remains unclear. Aims. Performance on monolingual PA, monolingual and emergent bilingual spelling was compared. In addition, PA and spelling in emergent bilingual Zulu–English speakers was explored to ascertain cross‐language transfer relationships. Sample. Thirty emergent bilingual Zulu–English and thirty monolingual English children in grade 2 participated. Method. Emergent bilinguals were assessed on Zulu PA, Zulu and English spelling skills. Monolinguals were assessed on English PA and English spelling skills. Results. Emergent bilinguals had more Zulu PA levels related to spelling English tasks than to spelling Zulu tasks, and both Zulu PA and Zulu spelling were positively related to English spelling tasks. Significant differences were found between L1 Zulu and English phoneme and rime PA levels, and L1 English and L2 English spelling tasks. Conclusions. Findings support the language‐universal hypothesis that L1 PA is related to spelling across languages in emergent bilinguals. In emergent bilinguals, both Zulu spoken proficiency and English‐only literacy instruction influences the underlying repertoire of PA skills used to spell within the L1 and the L2. Rime and phoneme PA and spelling skills in Zulu/English rely on language‐specific orthographic knowledge.     

Bilingualism,executive control,and age at diagnosis among people with early‐stage Alzheimer's disease in Wales

The observation of a bilingual advantage in executive control tasks involving inhibition and management of response conflict suggests that being bilingual might contribute to increased cognitive reserve. In support of this, recent evidence indicates that bilinguals develop Alzheimer's disease (AD) later than monolinguals, and may retain an advantage in performance on executive control tasks. We compared age at the time of receiving an AD diagnosis in bilingual Welsh/English speakers (n = 37) and monolingual English speakers (n = 49), and assessed the performance of bilinguals (n = 24) and monolinguals (n = 49) on a range of executive control tasks. There was a non‐significant difference in age at the time of diagnosis, with bilinguals being on average 3 years older than monolinguals, but bilinguals were also significantly more cognitively impaired at the time of diagnosis. There were no significant differences between monolinguals and bilinguals in performance on executive function tests, but bilinguals appeared to show relative strengths in the domain of inhibition and response conflict. Bilingual Welsh/English speakers with AD do not show a clear advantage in executive function over monolingual English speakers, but may retain some benefits in inhibition and management of response conflict. There may be a delay in onset of AD in Welsh/English bilinguals, but if so, it is smaller than that found in some other clinical populations. In this Welsh sample, bilinguals with AD came to the attention of services later than monolinguals, and reasons for this pattern could be explored further.     

Discrimination of coronal stops by bilingual adults: the timing and nature of language interaction

The current study was designed to investigate the timing and nature of interaction between the two languages of bilinguals. For this purpose, we compared discrimination of Canadian French and Canadian English coronal stops by simultaneous bilingual, monolingual and advanced early L2 learners of French and English. French /d/ is phonetically described as dental whereas English /d/ is described as alveolar. Using a categorial AXB task, the performance of all four groups was compared to chance and to the performance of native Hindi listeners. Hindi listeners performed well above chance in discriminating French and English /d/-initial syllables. The discrimination performance of advanced early L2 learners, but not simultaneous bilinguals, was consistent with one merged category for coronal stops in the two languages. The data provide evidence for interaction in L2 learners as well as simultaneous bilinguals; however, the nature of the interaction is different in the two groups.