Disentangling the effect of bilingualism in attention from socioeconomic influences: A lifespan approach

There is growing evidence that brain structure and cognitive performance can be moulded from various forms of experience. Bilingualism seems to form such an experience, with studies mainly showing a bilingual advantage over monolinguals in executive control of attention. This has been attributed to bilinguals’ lifelong practice in controlling two simultaneously active languages while using only one during communication. However, the problematic replicability of some of the main findings of relevant studies suggests that a confounding factor may have influenced their results. We suggest this could be the socioeconomic status (SES) of the participants, which has been inadequately controlled for in the majority of those studies, despite evidence on SES’s strong influences on the cognitive system. Also, research has largely neglected the possible effects of bilingualism in the other two main attention functions, alerting and orienting. Four experiments were designed to explore the bilingual effect in executive attention, alerting and orienting, in children, young and old adults, bilingual in Albanian and Greek or monolingual in Greek, all of low SES. Several cognitive tasks were used to detect the bilingual effect. An additional innovation of this investigation was the language-switching task we used as an index of bilingual proficiency, to compensate for the questionable reliability of self-report measures that have been used up to date for this purpose. This also enabled us to determine what level of bilingual experience is required to influence cognition and to explore possible commonalities between the mechanisms underlying bilingual language-switching and executive attentional control. Our results suggest that, when controlling for SES and when bilinguals are balanced, there is a bilingual effect in executive attention and alerting. However it is weaker than what has been suggested, as specific manipulations were required to detect it (i.e. individuals with age-related cognitive decline, under high working memory load).