Are there bilingual advantages on nonlinguistic interference tasks? Implications for the plasticity of executive control processes

Bilingualism enriches the poor: enhanced cognitive control in low-income minority children

This study explores whether the cognitive advantage associated with bilingualism in executive functioning extends to young immigrant children challenged by poverty and, if it does, which specific processes are most affected. In the study reported here, 40 Portuguese-Luxembourgish bilingual children from low-income immigrant families in Luxembourg and 40 matched monolingual children from Portugal completed visuospatial tests of working memory, abstract reasoning, selective attention, and interference suppression. Two broad cognitive factors of executive functioning-representation (abstract reasoning and working memory) and control (selective attention and interference suppression)-emerged from principal component analysis. Whereas there were no group differences in representation, the bilinguals performed significantly better than did the monolinguals in control. These results demonstrate, first, that the bilingual advantage is neither confounded with nor limited by socioeconomic and cultural factors and, second, that separable aspects of executive functioning are differentially affected by bilingualism. The bilingual advantage lies in control but not in visuospatial representational processes.

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.

Bilingualism: consequences for mind and brain

Building on earlier evidence showing a beneficial effect of bilingualism on children's cognitive development, we review recent studies using both behavioral and neuroimaging methods to examine the effects of bilingualism on cognition in adulthood and explore possible mechanisms for these effects. This research shows that bilingualism has a somewhat muted effect in adulthood but a larger role in older age, protecting against cognitive decline, a concept known as 'cognitive reserve'. We discuss recent evidence that bilingualism is associated with a delay in the onset of symptoms of dementia. Cognitive reserve is a crucial research area in the context of an aging population; the possibility that bilingualism contributes to cognitive reserve is therefore of growing importance as populations become increasingly diverse.

Ageing and bilingualism: Absence of a “bilingual advantage” in Stroop interference in a nonimmigrant sample

Previous research has found an advantage for bilinguals relative to monolinguals on tasks of attentional control. This advantage has been found to be larger in older adults than in young adults, suggesting that bilingualism provides a buffer against age-related declines in executive functioning. Using a computerized Stroop task in a nonimmigrant sample of young and older monolinguals and bilinguals, the current investigation tried to replicate previous findings of a bilingual advantage. A bilingual advantage would have been demonstrated by smaller Stroop interference (i.e., smaller increases in response time for incongruent than for neutral trials) for bilinguals than for monolinguals. The results showed that bilingual young adults showed a general speed advantage relative to their monolingual counterparts, but this was not associated with smaller Stroop interference. Older adults showed no effect of bilingualism. Thus, the present investigation does not find evidence of a bilingual advantage in young or older adults and suggests limits to the robustness and/or specificity of previous findings.

Self-assessment of individual differences in language switching

Language switching is omnipresent in bilingual individuals. In fact, the ability to switch languages (code switching) is a very fast, efficient, and flexible process that seems to be a fundamental aspect of bilingual language processing. In this study, we aimed to characterize psychometrically self-perceived individual differences in language switching and to create a reliable measure of this behavioral pattern by introducing a bilingual switching questionnaire. As a working hypothesis based on the previous literature about code switching, we decomposed language switching into four constructs: (i) L1 switching tendencies (the tendency to switch to L1; L1-switch); (ii) L2 switching tendencies (L2-switch); (iii) contextual switch, which indexes the frequency of switches usually triggered by a particular situation, topic, or environment; and (iv) unintended switch, which measures the lack of intention and awareness of the language switches. A total of 582 Spanish-Catalan bilingual university students were studied. Twelve items were selected (three for each construct). The correlation matrix was factor-analyzed using minimum rank factor analysis followed by oblique direct oblimin rotation. The overall proportion of common variance explained by the four extracted factors was 0.86. Finally, to assess the external validity of the individual differences scored with the new questionnaire, we evaluated the correlations between these measures and several psychometric (language proficiency) and behavioral measures related to cognitive and attentional control. The present study highlights the importance of evaluating individual differences in language switching using self-assessment instruments when studying the interface between cognitive control and bilingualism.

Bilingualism and inhibitory control influence statistical learning of novel word forms

We examined the influence of bilingual experience and inhibitory control on the ability to learn a novel language. Using a statistical learning paradigm, participants learned words in two novel languages that were based on the International Morse Code. First, participants listened to a continuous stream of words in a Morse code language to test their ability to segment words from continuous speech. Since Morse code does not overlap in form with natural languages, interference from known languages was minimized. Next, participants listened to another Morse code language composed of new words that conflicted with the first Morse code language. Interference in this second language was high due to conflict between languages and due to the presence of two colliding cues (compressed pauses between words and statistical regularities) that competed to define word boundaries. Results suggest that bilingual experience can improve word learning when interference from other languages is low, while inhibitory control ability can improve word learning when interference from other languages is high. We conclude that the ability to extract novel words from continuous speech is a skill that is affected both by linguistic factors, such as bilingual experience, and by cognitive abilities, such as inhibitory control.

The influence of expertise in simultaneous interpreting on non-verbal executive processes

This study aimed to explore non-verbal executive processes in simultaneous interpreters. Simultaneous interpreters, bilinguals without any training in simultaneous interpreting, and control monolinguals performed the Wisconsin card sorting task (WCST; Experiment 1) and the Simon task (Experiment 2). Performance on WCST was thought to index cognitive flexibility while Simon task performance was considered an index of inhibitory processes. Simultaneous interpreters outperformed bilinguals and monolinguals on the WCST by showing reduced number of attempts to infer the rule, few errors, and few previous-category perseverations. However, simultaneous interpreters presented Simon effects similar to those found in bilinguals and monolinguals. Together, these results suggest that experience in interpreting is associated with changes in control processes required to perform interpreting tasks.

When the tail counts: the advantage of bilingualism through the ex-gaussian distribution analysis

Several studies have documented the advantage of bilingualism with respect to the development of the executive control (EC) system. Two effects of bilingualism have been described in conflict resolution tasks: (a) bilinguals tend to perform the tasks faster overall, and (b) bilinguals tend to experience less interference from conflicting information, compared to monolinguals. The precise way in which the bilingual advantage relies on different EC mechanisms is still not well understood. The goal of the present article is to further explore how bilingualism impacts the EC system by performing a new analysis (Ex-Gaussian) of already reported data in which bilinguals and monolinguals performed a flanker task. Ex-Gaussian distribution analysis allows us to partial out the contribution of the normal and the exponential components of the RT distribution of the two groups. The fit of the raw data to the ex-Gaussian distribution showed two main results. First, we found that the bilingualism advantage in the overall speed of processing is captured by group differences in the normal (μ) and the exponential (τ) components of the distribution. Second, the bilingual advantage in the magnitude of the conflict effect is captured by group differences only in the exponential component. The results are discussed in terms of: (a) usefulness of the ex-Gaussian analysis as a tool to better describe the RT distribution, and (b) a new approach to explore the cognitive processes purportedly involved in instantiating the bilingualism advantage with respect to EC.