Likewise, if a bilingual person frequently switches between languages when speaking, it can confuse the listener, especially if that listener knows only one of the speaker’s languages. From a communicative standpoint, this is an important skill- understanding a message in one language can be difficult if your other language always interferes. 8 As a result, the constant juggling of two languages creates a need to control how much a person accesses a language at any given time. For instance, knowing more than one language can cause speakers to name pictures more slowly 7 and can increase tip-of-the-tongue states (where you’re unable to fully conjure a word, but can remember specific details about it, like what letter it starts with).

Having to deal with this persistent linguistic competition can result in language difficulties. 6 Even though the task does not require the bilingual people to engage their Chinese, they do so anyway. For example, when Chinese-English bilingual people judge how alike two English words are in meaning, their brain responses are affected by whether or not the Chinese translations of those words are written similarly. Furthermore, language co-activation is so automatic that people consider words in both languages even without overt similarity. 5 A Russian-English bilingual person asked to “pick up a marker” from a set of objects would look more at a stamp than someone who doesn’t know Russian, because the Russian word for “stamp,” “ marka,” sounds like the English word he or she heard, “marker.” 4 In cases like this, language co-activation occurs because what the listener hears could map onto words in either language. We tend to look at things that we are thinking, talking, or hearing about. Some of the most compelling evidence for language co-activation comes from studying eye movements.

For bilingual people, this activation is not limited to a single language auditory input activates corresponding words regardless of the language to which they belong. If you hear “can,” you will likely activate words like “candy” and “candle” as well, at least during the earlier stages of word recognition. Long before the word is finished, the brain’s language system begins to guess what that word might be by activating lots of words that match the signal. When a person hears a word, he or she doesn’t hear the entire word all at once: the sounds arrive in sequential order. Research has overwhelmingly shown that when a bilingual person uses one language, the other is active at the same time. 3 Over the past few decades, technological advances have allowed researchers to peer deeper into the brain to investigate how bilingualism interacts with and changes the cognitive and neurological systems. The Associated Press reports that up to 66 percent of the world’s children are raised bilingual. Europe and the United States are not alone, either. 2 Millions of Americans use a language other than English in their everyday lives outside of the home, when they are at work or in the classroom. 1 Even in the United States, which is widely considered to be monolingual, one-fifth of those over the age of five reported speaking a language other than English at home in 2007, an increase of 140 percent since 1980. In many countries that percentage is even higher-for instance, 99 percent of Luxembourgers and 95 percent of Latvians speak more than one language.

In a survey conducted by the European Commission in 2006, 56 percent of respondents reported being able to speak in a language other than their mother tongue. In fact, the majority of the world’s population is bilingual or multilingual. And for many people, this rich linguistic environment involves not just one language but two or more. We use language to communicate our thoughts and feelings, to connect with others and identify with our culture, and to understand the world around us.

We are surrounded by language during nearly every waking moment of our lives.

Cons of being monolingual