Reshaping the Mind: The Benefits of Bilingualism

Article excerpt

Studies have shown that bilingual individuals consistently outperform their monolingual counterparts on tasks involving executive control. The present paper reviews some of the evidence for this conclusion and relates the findings to the effect of bilingualism on cognitive organisation and to conceptual issues in the structure of executive control. Evidence for the protective effect of bilingualism against Alzheimer's disease is presented with some speculation about the reason for that protection.

Keywords: bilingualism, executive control, cognitive development, aging

All experiences leave their mark - they change how we respond to a similar situation in the future, create knowledge or expertise in particular areas, a change we usually call "learning," and as it is increasingly becoming apparent, change our brains. It follows, then, that experience has great potential for explaining the way that basic cognitive abilities develop, function, and change throughout the life span. Researchers have reported dramatic effects on brain structure and function following short intensive experiences, such as juggling (Draganski et al., 2004) or video-game playing (Green & Bavelier, 2008), and long-term experiences, such as careers in architecture (Salthouse & Mitchell, 1990) or taxi-driving (Maguire et al., 2000). Bilingualism is different from all of these: like juggling and playing video games it is intense, and like careers in architecture and driving taxis in London, it is sustained over a long period of time. However, unlike all these examples, bilinguals are typically not selected for a preexisting talent or interest, confusing the direction of cause and effect in the previous literature. In the vast majority of cases, individuals become bilingual through life circumstances.

The main empirical finding for the effect of bilingualism on cognition is in the evidence for enhanced executive control in bilingual speakers (review in Bialystok, Craik, Green, & Gollan, 2009). These effects have been found at all stages across the life span beginning in infancy (Kovács & Mehler, 2009) and toddlerhood (Poulin-Dubois, Blaye, Coutya, & Bialystok, 201 1), continuing through young (Carlson & Meltzoff, 2008) and middle childhood (Bialystok, 2011), into young adulthood (Costa, Hernández, & Sebastián-Galles, 2008), and older age (Bialystok, Craik, Klein, & Viswanathan, 2004). In all these cases, tasks that include a salient conflict (e.g., Simon task, Bialystok et al., 2004; Stroop task, Bialystok, Craik, & Luk, 2008; or flanker task, Costa et al.. 2008) or the need to inhibit a learned or habitual response (e.g., day-night task, Martin-Rhee & Bialystok, 2008) were performed better by bilingual participants than by their monolingual peers.

The key to understanding how bilingualism affects minds and brains is in the surprising, but well-documented, finding that both languages of a bilingual speaker are constantly active to some degree, even in strongly monolingual contexts where there is no reason to expect to use one of the languages. Evidence for this conclusion has come from behavioural studies in which interference from the participant's other language is found on experimental trials designed to maximize such effects (e.g., Beauvillain & Grainger, 1987; Colomé, 2001; Francis, 1999; Grainger, 1993; Hernandez, Bates, & Avila, 1996; Kroll & deGroot, 1997), patient studies in which interference from the irrelevant language is expressed as intrusions or complete language switches (e.g., Fabbro, Skrap, & Aglioti, 2000), and imaging studies in which interference from the nontarget language is salient (Marian, Spivey, & Hirsch, 2003; Martin, Dering, Thomas, & Thierry, 2009; RodriguezFornells, Rotte, Heinze, Nosselt, & Munte, 2002). This joint activation has profound implications for both linguistic and nonlinguistic processing.

If both languages of a bilingual speaker are active, then a problem in attention is introduced for bilinguals that does not exist for monolingual speakers. …