Ellen Bialystok

Bilingualism, Aging, and Cognitive Control: Evidence From the Simon Task

Previous work has shown that bilingualism is associated with more effective controlled processing in children; the assumption is that the constant management of 2 competing languages enhances executive functions (E. Bialystok, 2001). The present research attempted to determine whether this bilingual advantage persists for adults and whether bilingualism attenuates the negative effects of aging on cognitive control in older adults. Three studies are reported that compared the performance of monolingual and bilingual middle-aged and older adults on the Simon task. Bilingualism was associated with smaller Simon effect costs for both age groups; bilingual participants also responded more rapidly to conditions that placed greater demands on working memory. In all cases the bilingual advantage was greater for older participants. It appears, therefore, that controlled processing is carried out more effectively by bilinguals and that bilingualism helps to offset age-related losses in certain executive processes.

Cognitive Complexity and Attentional Control in the Bilingual Mind

In the analysis and control framework, Bialystok identifies analysis (representation) and control (selective attention) as components of language processing and has shown that one of these, control, develops earlier in bilingual children than in comparable monolinguals. In the theory of cognitive complexity and control (CCC), Zelazo and Frye argue that preschool children lack the conscious representation and executive functioning needed to solve problems based on conflicting rules. The present study investigates whether the bilingual advantage in control can be found in a nonverbal task, the dimensional change card sort, used by Zelazo and Frye to assess CCC. This problem contains misleading information characteristic of high-control tasks but minimal demands for analysis. Sixty preschool children, half of whom were bilingual, were divided into a group of younger (M = 4,2) and older (M = 5,5) children. All the children were given a test of English proficiency (PPVT-R) and working memory (Visually-Cued Recall Task) to assure comparability of the groups and then administered the dimensional change card sort task and the moving word task. The bilingual children were more advanced than the monolinguals in the solving of experimental problems requiring high levels of control. These results demonstrate the role of attentional control in both these tasks, extends our knowledge about the cognitive development of bilingual children, and provides a means of relating developmental proposals articulated in two different theoretical frameworks, namely, CCC and analysis-control.

Cognitive control and lexical access in younger and older bilinguals.

Ninety-six participants, who were younger (20 years) or older (68 years) adults and either monolingual or bilingual, completed tasks assessing working memory, lexical retrieval, and executive control. Younger participants performed most of the tasks better than older participants, confirming the effect of aging on these processes. The effect of language group was different for each type of task: Monolinguals and bilinguals performed similarly on working memory tasks, monolinguals performed better on lexical retrieval tasks, and bilinguals performed better on executive control tasks, with some evidence for larger language group differences in older participants on the executive control tasks. These results replicate findings from individual studies obtained using only 1 type of task and different participants. The confirmation of this pattern in the same participants is discussed in terms of a suggested explanation of how the need to manage 2 language systems leads to these different outcomes for cognitive and linguistic functions.

Bilingualism: The good, the bad, and the indifferent

The present paper summarizes research showing that bilingualism affects linguistic and cognitive performance across the lifespan. The effect on linguistic performance is generally seen as a deficit in which bilingual children control a smaller vocabulary than their monolingual peers and bilingual adults perform more poorly on rapid lexical retrieval tasks. The effect on cognitive performance is to enhance executive functioning and to protect against the decline of executive control in aging. These effects interact to produce a complex pattern regarding the effect of bilingualism on memory performance. Memory tasks based primarily on verbal recall are performed more poorly by bilinguals but memory tasks based primarily on executive control are performed better by bilinguals. Speculations regarding the mechanism responsible for these effects are described.

Bilingualism as a protection against the onset of symptoms of dementia

This study examined the effect of lifelong bilingualism on maintaining cognitive functioning and delaying the onset of symptoms of dementia in old age. The sample was selected from the records of 228 patients referred to a Memory Clinic with cognitive complaints. The final sample consisted of 184 patients diagnosed with dementia, 51% of whom were bilingual. The bilinguals showed symptoms of dementia 4 years later than monolinguals, all other measures being equivalent. Additionally, the rate of decline in Mini-Mental State Examination (MMSE) scores over the 4 years subsequent to the diagnosis was the same for a subset of patients in the two groups, suggesting a shift in onset age with no change in rate of progression.

Levels of Bilingualism and Levels of Linguistic Awareness.

A framework for relating degree of bilingualism to aspects of linguistic awareness is presented in which metalinguistic tasks are described in terms of their demands for analysis of knowledge or control of processing. Two studies are reported in which children differing in their level of bilingualism were given metalinguistic problems to solve that made demands on either analysis or control. The hypotheses were that all bilingual children would perform better than monolingual children on all metalinguistic tasks requiring high levels of control of processing and that fully bilingual children would perform better than partially bilingual children on tasks requiring high levels of analysis of knowledge. The results were largely consistent with these predictions. The findings are discussed in terms of the implications of bilingualism for cognitive and linguistic development. Research investigating the effects of bilingualism on a variety of academic, linguistic, and intellectual achievements has traditionally led to conflicting results. Many of the early studies that warned of disastrous effects of bilingualism on cognitive development (see Darcy, 1963, for review) were later found to lack proper controls, undermining any interpretation of those findings. Later work revealed a more promising intellectual prognosis for bilingual children. Peal and Lambert (1962), for example, showed how careful selection of subjects in the bilingual population could produce evidence of bilingual superiority on some intelligence tests. The relation between bilingualism and intelligence depended on factors such as social class, degree of language proficiency, and type of bilingualism (Cummins, 1976). A similar debate surrounds the examination of the relation between bilingualism and linguistic awareness. Evidence for a facilitating effect (Ben Zeev, 1977; Cummins, 1978;Ianco-Worrall, 1972), an inhibiting effect (Palmer, 1972), and no effect (Rosenblum & Pinker, 1983) of bilingualism have been reported. Some investigators have found effects in both directions when studying different samples of bilingual children (Ben Zeev, 1977; Cummins, 1978). Just as the early research on the intellectual effects of bilingualism failed to account for relevant factors, so too this problem requires consideration of a wider range of issues. To reconcile the diverse findings a more detailed examination of the two factors, bilingualism and linguistic awareness, is required. The claim proposed in this study is that the relation between bilingualism and linguistic awareness must be stated in terms of the degree and type of bilingualism as well as the degree and type of linguistic awareness.

Receptive vocabulary differences in monolingual and bilingual children.

Studies often report that bilingual participants possess a smaller vocabulary in the language of testing than monolinguals, especially in research with children. However, each study is based on a small sample so it is difficult to determine whether the vocabulary difference is due to sampling error. We report the results of an analysis of 1,738 children between 3 and 10 years old and demonstrate a consistent difference in receptive vocabulary between the two groups. Two preliminary analyses suggest that this difference does not change with different language pairs and is largely confined to words relevant to a home context rather than a school context.

The Development of Two Types of Inhibitory Control in Monolingual and Bilingual Children.

Previous research has shown that bilingual children excel in tasks requiring inhibitory control to ignore a misleading perceptual cue. The present series of studies extends this finding by identifying the degree and type of inhibitory control for which bilingual children demonstrate this advantage. Study 1 replicated the earlier research by showing that bilingual children perform the Simon task more rapidly than monolinguals, but only on conditions in which the demands for inhibitory control were high. The next two studies compared performance on tasks that required inhibition of attention to a specific cue, like the Simon task, and inhibition of a habitual response, like the day–night Stroop task. In both studies, bilingual children maintained their advantage on tasks that require control of attention but showed no advantage on tasks that required inhibition of response. These results confine the bilingual advantage found previously to complex tasks requiring control over attention to competing cues (interference suppression) and not to tasks requiring control over competing responses (response inhibition).

Critical Evidence A Test of the Critical-Period Hypothesis for Second-Language Acquisition

The critical-period hypothesis for second-language acquisition was tested on data from the 1990 U.S. Census using responses from 2.3 million immigrants with Spanish or Chinese language backgrounds. The analyses tested a key prediction of the hypothesis, namely, that the line regressing second-language attainment on age of immigration would be markedly different on either side of the critical-age point. Predictions tested were that there would be a difference in slope, a difference in the mean while controlling for slope, or both. The results showed large linear effects for level of education and for age of immigration, but a negligible amount of additional variance was accounted for when the parameters for difference in slope and difference in means were estimated. Thus, the patterh of decline in second-language acquisition failed to produce the discontinuity that is an essential hallmark of a critical period.

Short-Term Music Training Enhances Verbal Intelligence and Executive Function

Researchers have designed training methods that can be used to improve mental health and to test the efficacy of education programs. However, few studies have demonstrated broad transfer from such training to performance on untrained cognitive activities. Here we report the effects of two interactive computerized training programs developed for preschool children: one for music and one for visual art. After only 20 days of training, only children in the music group exhibited enhanced performance on a measure of verbal intelligence, with 90% of the sample showing this improvement. These improvements in verbal intelligence were positively correlated with changes in functional brain plasticity during an executive-function task. Our findings demonstrate that transfer of a high-level cognitive skill is possible in early childhood.