Language proficiency is a critically important factor in research on bilingualism, but researchers disagree on its measurement. Validated objective measures exist, but investigators often rely exclusively on subjective measures. We investigated if combining multiple self-report measures improves prediction of objective naming test scores in 36 English-dominant versus 32 Spanish-dominant older bilinguals (Experiment 1), and in 41 older Spanish–English bilinguals versus 41 proficiency-matched young bilinguals (Experiment 2). Self-rated proficiency was a powerful but sometimes inaccurate predictor and better predicted naming accuracy when combined with years of immersion, while percent use explained little or no unique variance. Spanish-dominant bilinguals rated themselves more strictly than English-dominant bilinguals at the same objectively measured proficiency level. Immersion affected young more than older bilinguals, and non-immersed (English-dominant) more than immersed (Spanish-dominant) bilinguals. Self-reported proficiency ratings can produce spurious results, but predictive power improves when combined with self-report questions that might be less affected by subjective judgements.

Knowing the sentence structures (i.e., information that guides the assembly of words into sentences) is crucial in language knowledge. This knowledge must be stable for successful communication, but when learning another language that uses different structures, speakers must adjust their structural knowledge. Here, we examine how newly acquired second language (L2) knowledge influences first language (L1) structure knowledge. We compared two groups of Korean speakers: Korean-immersed speakers living in Korea (with little English exposure) versus English-immersed speakers who acquired English late and were living in the US (with more English exposure). We used acceptability judgment and sentence production tasks on Korean sentences in English and Korean word orders. Results suggest that acceptability and structural usage in L1 change after exposure to L2, but not in a way that matches L2 structures. Instead, L2 exposure might lead to increased difficulties in the selection and retrieval of word orders while using L1.

Spanish–English bilinguals switched between naming pictures in one language and either reading-aloud or semantically classifying written words in both languages. When switching between reading-aloud and picture-naming, bilinguals exhibited no language switch costs in picture-naming even though they produced overt language switches in speech. However, when switching between semantic classification and picture-naming, bilinguals, especially unbalanced bilinguals, exhibited switch costs in the dominant language and switch facilitation in the nondominant language even though they never switched languages overtly. These results reveal language switching across comprehension and production can be cost-free when the intention remains the same. Assuming switch costs at least partially reflect inhibition of the nontarget language, this implies such language control mechanisms are recruited only under demanding task conditions, especially for unbalanced bilinguals. These results provide striking demonstration of adaptive control mechanisms and call into question previous claims that language switch costs necessarily transfer from comprehension to production.

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.

Self-ratings of language proficiency are ubiquitous in research on bilingualism, but little is known about their validity, especially when the same scale is used across different types of bilinguals. Self-ratings and picture naming data from 1044 Spanish–English and 519 Chinese–English bilinguals were analyzed in five between- and within-population comparisons. Chinese–English bilinguals scored more extremely than Spanish–English bilinguals, and in opposite directions at different endpoints of the self-ratings scale. Regrouping bilinguals by dominant language, instead of language membership, reduced discrepancies but significant group differences remained. Population differences appeared even in English, though this language is shared between populations. These results demonstrate significant problems with self-ratings, especially when comparing bilinguals of different language combinations; and subgroups of bilinguals who speak the same languages but vary in acquisition history and/or dominance. Objective proficiency measures (e.g., picture naming or proficiency interviews) are superior to self-ratings, to maximize classification accuracy and consistency across studies.

The commentaries on our Keynote article “Psycholinguistic, cognitive, and neural implications of bimodal bilingualism” were enthusiastic about what can be learned by studying bilinguals who acquire two languages that are understood via distinct perceptual systems (vision vs. audition) and that are produced with distinct linguistic articulators (the hands vs. the vocal tract). The authors also brought out several new ideas, extensions, and issues related to bimodal bilingualism, which we discuss in this reply.

This study investigated the relationship between bilingualism and task switching ability using a standardized measure of switching and an objective measure of bilingual language proficiency. Heritage Language (HL) speaking Spanish-English and Mandarin-English bilinguals and English speaking monolinguals completed all four subtests of the Color-Word Interference Test (CWIT), an English verbal fluency task, and a picture naming test (the Multilingual Naming Test) in English. Bilinguals also named pictures in their HL to assess HL proficiency. Spanish-English bilinguals were advantaged in task switching, exhibiting significantly smaller switching cost than monolinguals, but were disadvantaged in verbal fluency and picture naming. Additionally, performance on these cognitive and linguistic tasks was related to degree of HL proficiency, so that increased ability to name pictures in Spanish was associated with greater switching advantage, and greater disadvantage in both verbal fluency and picture naming. Mandarin-English bilinguals, who differed from the Spanish-English bilinguals on several demographic and language-use characteristics, exhibited a smaller but statistically significant switching advantage, but no linguistic disadvantage, and no clear relationship between HL proficiency and the switching advantage. Together these findings demonstrate an explicit link between objectively measured bilingual language proficiency and both bilingual advantages and disadvantages, while also showing that consequences of bilingualism for cognitive and linguistic task performance can vary across different language combinations. (JINS, 2015, 21, 531–544)

Bimodal bilinguals, fluent in a signed and a spoken language, exhibit a unique form of bilingualism because their two languages access distinct sensory-motor systems for comprehension and production. Differences between unimodal and bimodal bilinguals have implications for how the brain is organized to control, process, and represent two languages. Evidence from code-blending (simultaneous production of a word and a sign) indicates that the production system can access two lexical representations without cost, and the comprehension system must be able to simultaneously integrate lexical information from two languages. Further, evidence of cross-language activation in bimodal bilinguals indicates the necessity of links between languages at the lexical or semantic level. Finally, the bimodal bilingual brain differs from the unimodal bilingual brain with respect to the degree and extent of neural overlap for the two languages, with less overlap for bimodal bilinguals.

In this study, we investigated dual-language decline in non-balanced bilinguals with probable Alzheimer’s disease (AD) both longitudinally and cross-sectionally. We examined patients’ naming accuracy on the Boston Naming Test (BNT: Kaplan et al., 1983) over three testing sessions (longitudinal analysis) and compared their performance to that of matched controls (cross-sectional analysis). We found different longitudinal and cross-sectional patterns of decline: Longitudinally, the non-dominant language seemed to decline more steeply than the dominant language, but, cross-sectionally, differences between patients and controls were larger for the dominant than for the non-dominant language, especially at the initial testing session. This differential pattern of results for cross-sectional versus longitudinal decline was supported by correlations between decline measures and BNT item characteristics. Further studies will be needed to better characterize the nature of linguistic decline in bilinguals with AD; however, these results suggest that representational robustness of individual lexical representations, rather than language membership, might determine the time course of decline for naming in bilinguals with AD. (JINS, 2014, 20, 1–13)

Studies have shown reduced Stroop interference in bilinguals compared to monolinguals defined dichotomously, but no study has explored how varying degrees of second language fluency, might affect linguistic inhibitory control in the first language. We examined effects of relative English fluency on the ability to inhibit the automatic reading response on the Golden version of the Stroop Test administered in Spanish. Participants were 141 (49% male) adult native Spanish speakers from the U.S.–Mexico border region (education range = 8–20 and age range = 20–63). A language dominance index was calculated as the ratio of English words to total words produced in both languages using the Controlled Oral Word Association Test with letters PMR in Spanish and FAS in English. Greater degree of English fluency as measured by the dominance index predicted better speed on the Stroop incongruent trial independent of education effects. On the other hand, neither the dominance index nor education predicted performance on the word reading and color-naming trials. These results suggest an advantage in inhibitory control among those with greater second-language ability. (JINS, 2014, 20, 342–348)

This study examines the convergence and divergence between subjective and objective measures of language proficiency for assessing language dominance in Mandarin–English bilinguals. Sixty-two young adults (Experiment 1) and 27 children (Experiment 2) provided self-ratings of proficiency level (or were rated by their parents), were interviewed for spoken proficiency, and named pictures in the Multilingual Naming Test (MINT) and (in Experiment 1 only) the Boston Naming Test. In Experiment 1, the four measures converged in the number of people classified into different dominance groups but both naming tests indicated greater English dominance than self-report and interview measures. In Experiment 2, parent report and interview measures converged in dominance classifications but the MINT indicated higher degrees of English dominance. To a large extent bilinguals were able to classify themselves (or their children) into dominance groups but some mismatches between measures in dominance classification were observed for all age and dominance groups. These results, together with previous findings with Spanish–English bilingual adults (Gollan et al., 2012), suggest that bilinguals may shift to English dominance in confrontation naming before they do so in conversational fluency, and that dominance shifts persist throughout the lifespan but may be relatively more pronounced in children. These findings caution against the use of self-reports as the sole means of classifying bilinguals into dominance groups and support a multi-measure approach including direct assessment of the relevant linguistic domain.

The current study explored the picture naming performance of patients with Alzheimer's disease (AD). First, we evaluated the utility of the Multilingual Naming Test (MINT; Gollan et al., 2011), which was designed to assess naming skills in speakers of multiple languages, for detecting naming impairments in monolingual AD and amnestic mild cognitive impairment (MCI). If the MINT were sensitive to linguistic impairment in AD, using it in clinical practice might have advantages over using tests exclusively designed for English monolinguals. We found that the MINT can be used with both monolinguals and bilinguals: A 32-item subset of the MINT is best for distinguishing monolingual patients from controls, while the full MINT is best for assessing degree of bilingualism and language dominance in bilinguals. We then investigated the cognitive mechanisms underlying naming impairment in AD. To this end, we explored which MINT item characteristics best predicted performance differences between monolingual patients and controls. We found that contextual diversity and imageability, but not word frequency (nor words’ number of senses), contributed unique variance to explaining naming impairments in AD. These findings suggest a semantic component to the naming impairment in AD (modulated by names’ semantic richness and network size). (JINS, 2013, 19, 1–12)

The present study aimed to examine if bilingualism affects executive functions and verbal fluency in Marathi and Hindi, two major languages in India, with a considerable cognate (e.g., activity is actividad in Spanish) overlap. A total of 174 native Marathi speakers from Pune, India, with varying levels of Hindi proficiency were administered tests of executive functioning and verbal performance in Marathi. A bilingualism index was generated using self-reported Hindi and Marathi proficiency. After controlling for demographic variables, the association between bilingualism and cognitive performance was examined. Degree of bilingualism predicted better performance on the switching (Color Trails-2) and inhibition (Stroop Color-Word) components of executive functioning; but not for the abstraction component (Halstead Category Test). In the verbal domain, bilingualism was more closely associated with noun generation (where the languages share many cognates) than verb generation (which are more disparate across these languages), as predicted. However, contrary to our hypothesis that the bilingualism “disadvantage” would be attenuated on noun generation, bilingualism was associated with an advantage on these measures. These findings suggest distinct patterns of bilingualism effects on cognition for this previously unexamined language pair, and that the rate of cognates may modulate the association between bilingualism and verbal performance on neuropsychological tests. (JINS, 2012, 18, 305–313)

This study investigated correspondence between different measures of bilingual language proficiency contrasting self-report, proficiency interview, and picture naming skills. Fifty-two young (Experiment 1) and 20 aging (Experiment 2) Spanish–English bilinguals provided self-ratings of proficiency level, were interviewed for spoken proficiency, and named pictures in a Multilingual Naming Test (MINT); in Experiment 1, the Boston Naming Test (BNT) was also used. Self-ratings, proficiency interview, and the MINT did not differ significantly in classifying bilinguals into language-dominance groups, but naming tests (especially the BNT) classified bilinguals as more English-dominant than other measures. Strong correlations were observed between measures of proficiency in each language and language-dominance, but not degree of balanced bilingualism (index scores). Depending on the measure, up to 60% of bilinguals scored best in their self-reported non-dominant language. The BNT distorted bilingual assessment by underestimating ability in Spanish. These results illustrate what self-ratings can and cannot provide, illustrate the pitfalls of testing bilinguals with measures designed for monolinguals, and invite a multi-measure goal-driven approach to classifying bilinguals into dominance groups.