Bilingualism and brain lateralization of attentional networks

Different sides of the brain specialize in different tasks. For example, language processing usually takes place in the left side of the brain, whereas attention is thought to take place mostly in the right side of the brain. This division of labour between the different brain hemispheres is called lateralization. Some researchers have suggested that if people practice a particular skill until they become very good at it, then that skill may become less lateralized (i.e., it will be more spread out between the two sides of the brain, rather than concentrated in a single side).

One area where bilinguals have been shown to outperform monolinguals is attention – for example, someone who speaks Spanish and English has had a lot of practice of attention-sapping tasks, such as switching between two languages, or ignoring Spanish words when speaking English.

If bilinguals are very skilled at paying attention, and if being very skilled at something means that skill is less likely to be concentrated in one side of your brain, then maybe paying attention is less lateralized in bilinguals than it is in monolinguals. That was the question this study wanted to find out.

To do this, the authors tested a group of bilinguals and a group of monolinguals. Both groups participated in attention tasks, such as noting the direction of an arrow on a computer screen. They either saw the tasks in their right visual field (which connects with the left side of the brain) or their left visual field (which connects with the right side of the brain). We know that in monolinguals, attention is concentrated in the right side of the brain, so we would expect them to perform better on the tasks they saw in their left visual field, which they did. But what about bilinguals? The bilinguals performed equally well when they saw they tasks in their right or their left visual field, suggesting that, as predicted, their attention network had spread out over both sides of their brain.

In line with previous research, the bilinguals also performed better than the monolinguals on the attention tasks over all – yet another reason to learn a language!

This is a summary of the following published article:

Marzecová, A., Asanowicz, D., Krivá, L. U., & Wodniecka, Z. (2013). The effects of bilingualism on efficiency and lateralization of attentional networks. Bilingualism: Language and Cognition, 16(03), 608-623.