Many people who live in Europe and Asia can speak two or more languages. For example, more the 80% of Swedes can speak English as well as Swedish. This means that people of average IQ are capable of speaking more than one language with a reasonable degree of fluency. Of course, those who speak 4 or 5 different languages are probably more prevalent among those of higher than average IQ.
There are many reasons why people of high IQ may not speak English with high fluency. The most frequent cause is lack of exposure. We learn the vocabulary, structure and pronunciation of a language by immersing ourselves in an environment where that language is spoken. If a person of high IQ is not fluent in English, it suggests that they haven’t spent a great deal of time in an environment in which English is spoken.
People who learn English after adolescence will typically speak with a dialect and therefore appear not to be fluent. We all speak with accents in any language learned after adolescence. An interesting analysis of the difficulty in distinguishing between the “l” and “r” sounds experienced by those who speak Mandarin Chinese is presented in Alex Liang’s video accessible at: Why do Chinese people confuse the L & R sounds in English?
In The Brain: The Story of You, neuroscientist David Eagleman notes (p. 9), “A baby born in Japan and a baby born in America can hear and respond to all the sounds in both languages. Through time, the baby raised in Japan will lose the ability to distinguish between, say, the sounds of R and L, two sounds that aren’t separated in Japanese.”
In short, a lack of fluency in English is not related to IQ, but to exposure and the stage in life when the language is learned.
