Bilinguals Perform Better at Non-Verbal Tests

When communicating, bilinguals must successfully manage two conflicting languages; one must be accessed whilst the other is suppressed, in order to avoid involuntary language switching. The cognitive demands of this task are thought to be the origin of the bilingual advantage in executive control.

A series of studies have demonstrated that bilinguals outperform their peers on tests of non-linguistic interference. Bilingual children, middle aged adults and older adults consistently record faster global reaction times in the Simon task (Bialystok, Martin and Viswanathan, 2005; Martin-Rhee and Bialystok, 2008), the spatial Stroop/Simon arrows task (Bialystok, 2006; 2008), and flanker arrows tasks such as the Attention Networks Task (Costa, Hernandez and Sebastian-Galles, 2008; Carlson and Meltzoff, 2008; Emmorey et al., 2009). These computer-based neuropsychological tasks all require participants to respond to a series of stimuli as quickly and accurately as possible; the interference comes from conditions where the stimuli and the response required are incongruent, typically resulting in slower reaction times.

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Fortunately, a study from Tao et al. (2011) makes good progress in addressing these gaps in the literature. The authors compared the efficiency of the attention networks of young Australian adults who were English monolinguals or Chinese– English bilinguals. The bilingual group was further divided according to age of acquisition: early bilinguals, who had arrived in Australia before the age of 6, and had received their formal education in English; and late proficiency bilinguals, who had arrived in Australia between the ages of 12 and 19 years old. The efficiency of three attention networks – alerting (achieving and maintaining an alert state), orienting (selecting information from sensory input), and executive control (monitoring and resolving conflict) – as well as the hemispheric symmetry of these networks, was measured using Lateralized Attention Network Test (LANT), designed by Green et al. (2008). (This is an adaptation of the Attention Network Test described in detail in the methods section and Box B below.)

Both bilingual groups significantly outperformed the monolingual group, suggesting that the mastery of two very different grammars and lexicons produces the bilingual advantage found in bilinguals speaking two similar languages. The early proficiency group demonstrated significantly faster reaction times in all conditions; the authors suggested was due to the enhancement of monitoring systems (Costa et al. 2009) resulting from early bilingualism, though they also acknowledged that this could also be simply attributed to greater vigilance. Fascinatingly, however, the late proficiency bilingual showed the greatest advantage in conflict resolution conditions; the authors attributed this to greater reliance on the executive network in later second language acquisition, both in order to stave off greater interference from their “more solidified” first language and to support the processing of the weaker second language.

Early bilingual children perform better at sensory tasks, while children who became bilingual at adolescence perform better at conflict resolution tasks.