A recent study has found the mechanism by which the brain process more than one language. Being fluent in just one language means knowing about 30,000 words.
"The inherent characteristics of the words - how they sound - provide enough information to distinguish which language a word belongs to," said Mike Vitevitch, psycholinguist at the University of Kansas.
"Given how different the words in one language sound to the words in the other language, it seems like a lot of extra and unnecessary mental work to add a label to each word to identify it as being from one language or the other," he added.
He compared the situation to the example of having two different fruits - orange and an apple in a refrigerator. The apples represent one language and the oranges represent another language.
The fridge is that part of memory known as the lexicon, which contains knowledge about language.
He explained that to find an apple you just look for the round red thing in the fridge and to find an orange you just look for the round orange thing in the fridge.
Similarly, how words in one language tend to sound different from words in another language, parents who speak different languages should not worry that their children will be confused or somehow harmed by learning two languages, said Vitevitch.
"Most people in most countries in the world speak more than one language. If the U.S. wants to successfully compete in a global economy we need people who can communicate with potential investors and consumers in more than one language," Vitevitch added.
The study appears in the online edition of Bilingualism: Language and Cognition.