Do bilinguals have an internal switch that stops their two languages from interfering with each other, or are both languages always "on"? The fact that bilinguals aren't forever spurting out words from the wrong language implies there's some kind of switch. Moreover, in 2007, brain surgeons reported evidence for a language switch when their cortical prodding with an electrode caused two bilingual patients to switch languages suddenly and involuntarily.
On the other hand, there's good evidence that languages are integrated in the bilingual mind. For example, bilinguals are faster at naming an object when the word for that object is similar or the same in the two languages they speak (e.g. ship/schip in English and Dutch).
Now Eva Van Assche and colleagues have provided further evidence for the idea of bilingual language integration by showing that a person's second language affects the way that they read in their native language.
The researchers recorded the eye movements of 45 bilingual Belgian students as they read sentences in their native Dutch tongue. The key finding was that they read Dutch words faster when the equivalent word in their second language, English, was similar or the same as the Dutch word. Specifically, they spent less time fixating on words like "piloot" ("pilot" in English) than on control words like "eend" (that's "duck" in English).
Van Aassche and her colleagues said this shows that even when bilinguals read sentence after sentence in their native tongue, access to words in their second language remains open, rather than switched off, thus having an effect on the way the native language is processed.
"Becoming a bilingual means one will never read the newspaper again in the same way," they concluded. "It changes one of people's seemingly most automatic skills, namely, reading in one's native language."
Van Assche E, Duyck W, Hartsuiker RJ, & Diependaele K (2009). Does Bilingualism Change Native-Language Reading? Cognate Effects in a Sentence Context. Psychological science : a journal of the American Psychological Society / APS PMID: 19549082
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