Whether it happens early or late in life, the acquisition of two or more languages has been linked to improved cognitive flexibility. A team of researchers from Quebec chose to study the way in which bilingual and monolingual brains function while doing the Simon task, an exercise which involves neutralizing irrelevant secondary information to concentrate on the relevant information. How can bilingualism increase our capacity for multitasking?

Numerous studies have shown the advantages of being bilingual or multilingual, particularly in improving the functional efficiency of older people as well as reducing interferences from irrelevant stimuli in daily life. The Simon task is often used to compare mechanisms of control and interference in monolinguals and bilinguals.

The Simon task

You are sitting in front of a computer screen on which a colored square appears from one side; depending on the color of the square, you must press the button on the left or the right as quickly as possible. For example, you must press the button on the left when the square is blue and the button on the right when the square is yellow. However, a secondary stimulus makes the task more complicated since the square can appear from either the left or the right side of the screen. This creates a double task because locating the square activates a rapid and automatic channel (impulsive), while determining the color of the square activates a slower controlled channel. An interference occurs when the color of the square appears on the side opposite to its corresponding button. In this situation of conflict, we need to suppress our impulsive response to answer correctly using our controlled response.

Previous studies have shown that bilinguals have a shorter response time than monolinguals, and that this difference is enhanced amongst elderly groups. The current study, published in the Journal of Neurolinguistics, aimed to identify the neurofunctional networks that affect participants’ behavior during the Simon task. The scientists studied the MRI results of the sample group: 10 monolingual French speakers (average age 74.5 years, 4 males) and 10 bilingual French-English speakers (average age 74.2; 4 males), all with similar educational backgrounds. Participants had one practice run to familiarize themselves with the Simon task (with the square in the center of the screen) before completing the actual test which consisted of 30 congruent stimuli (where the position of the square corresponds to the correct color), and 30 incongruent stimuli (situation of conflict). Each response had a time limit of two seconds.

The researchers discovered that for monolingual participants a large circuit of neurons was activated requiring multiple connections in several zones of the brain involving motricity, executive function, visual processing and interference control. In contrast, the MRI scans of bilingual participants showed a smaller circuit with greater connectivity in the left inferior temporal sulcus (area responsible for visuospatial processing). Therefore, bilingual brains resolve situations of conflict more efficiently than monolingual brains, using fewer areas of the brain, but greater connectivity in the areas best suited to resolving the task.

In conclusion, the resource optimization that has developed in the bilingual brain could explain their superior performance, and even a greater resistance to the effects of cognitive aging.