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.