Ground-breaking research from the University of California reveals that when we hear words, it's giving the brain what might be described as an all-over work out. As we learn more about this, we could find that hearing has far more important implications for keeping our brains healthy than we've realised up to now.
Each of our brains has its very own dictionary that it has built up over our life-time of experience. Every word we hear is connected to other words by how they sound, what words they occur next to, as well as the meaning of the word.
If we hear the word “bat”, for example, our brain has to work out whether the meaning is the furry mammal, the piece of wood used for hitting balls, or the verb meaning to knock something away. The brain does this by using its internal dictionary to work out the most likely meaning based on context and how common the word (and its meaning) is.
And because each word is connected to other words through memories and previous usage, our brain will subconsciously begin thinking of other words and ideas that are connected with it.
Studies have found that specific areas in the brain respond more readily to specific categories. There are brain areas for concrete words (like “cat” and “pot plant”), abstract words (like “love” or “determination”), action words (like “run” or “sleep”) and social words.
Conversations normally consist of full sentences, which of course contain multiple types of words. Which means that different areas of the brain get stimulated by what we hear, every time we hear.
It was generally believed (at least if you look at photographs of brain activity) that this brain activity for words was restricted to small areas of the brain concerned with language, mainly in the temporal lobe.
But a surprise came recently with new research by the University of California. The researchers asked people to listen to more than two hours of stories from the Moth Radio Hour, whilst their brain activity was monitored then matched up to the words they were hearing when the brain activity lit up. So if a listener heard the word “top”, they would register the part of the brain that “lit up”.
By doing this, Dr Alexander Huth and his team were able to able to create a map of the brain's dictionary, based on meaning – and they discovered that this map was fairly consistent across different participants. In other words, where my brain gets activated by the word “top” is likely to be similar to yours. This map then allowed the researchers to predict which areas of a new participant's brain was likely to light up when they heard specific words.
It is a stunning piece of work that is likely to forever change the way we view language in the brain, because it doesn't simply show a small part of the brain being stimulated – it shows an all-over brain work out!
It's still far too early to know what implications mishearing has on the brain's map. But what we can safely say is that if someone doesn't hear a word, the brain won't get stimulated in that area of the brain's map.
Also I would predict that if someone mishears a word it will activate a different area of the brain, and the words that are less common or more complex are likely to be the ones that will suffer most in terms of reduced brain activity. I can't help wondering what the longer terms effects of this might be.
We know the brain depends on constant stimulation to remain healthy, so the good news is that by maintaining our ability to hear words as well as possible, we are giving our brain's an all-over work out without even trying.