SPEAKING two languages slows the brain鈥檚 decline with age, according to a study comparing monolingual and bilingual people. It is the first to show the benefits of bilingualism for the brains of elderly people.
The reason, say researchers, is that bilingual people spend their lives ignoring one language while speaking the other. This gives them constant practice at shutting out information irrelevant to the task in hand.
To find out if this ability extends to other tasks, Ellen Bialystok of York University in Toronto, Canada, and her colleagues subjected 150 bi- and monolingual volunteers aged between 30 and 88 to a psychological test that measures a person鈥檚 ability to avoid distractions. All the volunteers spoke English, but roughly half also spoke Tamil, which originated in southern India.
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Volunteers had to respond to transient symbols on a computer screen by pressing a key either to the right or to the left of the keyboard, depending on the symbol鈥檚 colour. Sometimes the symbol appeared on the same side as the key to be pressed, and sometimes on the opposite side. The shorter the subject鈥檚 reaction time for 鈥渨rong鈥� side symbols compared to 鈥渞ight鈥� side symbols, the more they are able to stick to the task and avoid distraction.
Bilingual volunteers tended to react faster than monolingual people, and the decline in their ability with age was less marked (Psychology and Aging, vol 19, p 290).