DAVID GREENE, HOST:
On a Thursday, it's MORNING EDITION, from NPR News. I'm David Greene.
RENEE MONTAGNE, HOST:
And I'm Renee Montagne. Good morning.
And now a story about a duck - or, more precisely, a story about what your brain just did when you heard the word duck. Chances are it created an image of a web-footed waterfowl. Your brain also may have recalled the sound of quacking, or the feel of feathers.
NPR's Jon Hamilton reports on new research suggesting that these mental simulations are essential to understanding language.
JON HAMILTON, BYLINE: Just a few decades ago, many linguists thought the human brain had evolved a special module for language. The idea that our brains have some unique structure or system seemed plausible. After all, no animal can use language the way people can. But in the 1990s, scientists began testing the theory using new MRI technology that let them watch the brain respond to words.
And Ben Bergen of the University of California, San Diego says what they saw didn't look like a module.
BEN BERGEN: They found something totally surprising, and that was that it's not just certain, specific little regions in the brain, regions dedicated to language that were lighting up. It was kind of a whole-brain type of process.
HAMILTON: Bergen says if you were to put someone in a brain scanner and read them a sentence like...
BERGEN: The shortstop threw the ball to first base.
HAMILTON: You would see a distinct pattern of activity.
BERGEN: What you'd see is that parts of their brain would light up that are dedicated to vision. Then the motor centers in their brain would light up. And the question was, why? They're just listening to language. Why would they be preparing to act? Why would they be thinking that they were seeing something?
HAMILTON: Bergen says the answer is that when we encounter words describing a particular action, our brain simulates the experience.
BERGEN: The way that you understand an action is by recreating in your vision system what it would look like to perceive that event, and recreating in your motor system what it would be like to be that short stop, to have the ball in your hand and to release it.
HAMILTON: Bergen says the brain appears to be taking words, which are just arbitrary symbols, and translating them into things we can see or hear or do. He describes this theory of language in his new book "Louder Than Words."
Bergen says it's easy to understand how words could cause the brain to recreate familiar things, like throwing a baseball or seeing a duck. But what about things we've probably never seen? Like a flying pig.
BERGEN: So a flying pig isn't something that actually exists in the real world.
HAMILTON: And yet I'm seeing one in my head right now.
BERGEN: That's right. And I know something about the flying pig in your head. It has two wings.
BERGEN: And they're attached symmetrically.
BERGEN: Probably right around the shoulder blades.
HAMILTON: Right around the shoulder blades.
BERGEN: Right. And it uses those wings probably to propel itself.
HAMILTON: Yes, it's flying with those wings, in my head.
BERGEN: That's right.
HAMILTON: A flying pig has meaning to me, because my brain is using things I've seen - pigs and birds - to imagine something I've never seen. Of course, that's my version of a flying pig. Bergen says other people see a pig with a cape, flying like Superman.
In either case, though, the meaning is based on our own experience. And Bergen says that's also the case when we use language to convey abstract ideas like truth or justice, or even the word meaning.
BERGEN: What we actually say when we talk about meaning is: Do you see what I mean? Is my point crystal clear? Maybe, let's shed a little light on the subject.
HAMILTON: Bergen says what we're doing is extending our physical experiences - in this case, things we've seen - by turning them into metaphors. And he says we do this all the time in conversation. We grasp the truth. We dodge questions. We fall in love.
Philosophers have been debating the importance of metaphors like these since the time of Aristotle. But now, brain researchers are getting involved, people like Krish Sathian at Emory University. Sathian has been studying an area of the brain that responds to the texture of an object, whether it feels smooth or rough. And he wondered whether the same area would respond when we use textures like smooth or rough as metaphors.
KRISH SATHIAN: So we ran this experiment where we had people listen to textural metaphors, like he had a rough day, and contrasted the activity with sentences more or less matched for meaning, but without a textural metaphor, like he had a bad day.
HAMILTON: Sathian says the results suggest that in the brain, at least, a rough day has something in common with a sheet of sandpaper.
SATHIAN: When listening to these sentences containing textural metaphors, we found activity in the part of the brain that's involved when we feel surfaces.
HAMILTON: Sathian says research like this adds to the evidence that the human brain is not processing language in some special module.
SATHIAN: The brain is really working as a very highly distributed system. So it's really very hard to think about any experience that we have in a highly modular fashion, in the sense that it's being processed only in one region of the brain, and not in others.
HAMILTON: Ben Bergen says what's amazing is that we're able to do so much with language, using the same basic brain structures found in monkeys and apes.
BERGEN: What evolution has done is to build a new machine: A capacity for language, something that nothing else in the known universe can do. And it's done so using the spare parts that it had lying around in the old primate brain.
HAMILTON: The parts involved in seeing and feeling and moving.
Jon Hamilton, NPR News.