How do our brains process language? David Davila, an American neuroscience student and winner of the FameLab science communication competition final in France, explains what sign language tells us about the way we communicate. He will join the international finals in Cheltenham on 3-5 June 2014.
Are we clear about what we mean by 'language'?
What is a language? The definition in Oxford Dictionaries (online) is a 'method of human communication, either spoken or written, consisting of the use of words in a structured and conventional way'.
Well, Oxford Dictionaries, for the first time in my life, I would beg to disagree with you.
One thing is clear -- language is complicated. So when neuroscientists start asking questions about how language is represented in the brain, we have to be careful about what we are actually asking. Are we asking about how the brain uses the ‘rules’ of syntax to create a consistent language? Or are we asking how our brain translates ideas or objects into words?
Because language is such an abstract but complicated subject, it’s important to keep our minds open to the possibilities of how the brain might work, before we make assumptions.
Patients with brain damage provide clues about how language production works
One of the first hints into how language functions in the brain can be found in patients who have sustained brain injuries. The 19th century French physician Pierre Paul Broca studied many patients who had damage to the same area of the brain, who then displayed severe deficits in language. This part of the brain is now known as Broca’s area. One notable subject, 'Tan', seemed like he knew what he wanted to say, but when he opened his mouth, the only thing that came out was 'Tan tan tan tan tan taaaaaaan. Tan tan?'.
It’s now well-established that Broca’s area is involved in speech production, explaining the deficits of Dr. Broca’s patients. But we can go even further in this line of questioning. 'Tan' had all the necessary motor functions and vocal expressiveness to use language, but he lacked this key language production area. This meant that he was unable to communicate.
What if we could study someone who had the opposite problem -- a person who is able to use language, but who doesn't use typical motor functions and vocal expression to do so?
Sign language shows us that language is more than just a spoken or written system
Enter sign language. We've recently found that certain parts of Broca’s area in the brain are activated when sign language speakers make signs, just like when other language speakers say words. This implies that sign language -- as far as the brain is concerned -- is just another abstract language system.
Sorry, Oxford Dictionaries. According to our brains, not all language is spoken or written.
FameLab aims to discover charismatic, up-and-coming scientists who can inspire people to see the world from a new perspective. The competition is the brainchild of The Times Cheltenham Science Festival and is delivered by the British Council in 25 countries.
Did you know: the UK government recognised British Sign Language as an official language in 2003.
You can also read this article in French.