By Jessica Love
October 20, 2011
The relationship between the body and the mind is strange and incestuous. There’s no controversy here: the placebo effect is real (and robust), and psychologists know that people need physical experience with the world to know how to think about it. Place a seven-month-old baby who has already learned to crawl at the edge of a “visual cliff” (a piece of clear Plexiglas spanning a drop-off), and the infant will initially recoil, demonstrating a healthy fear for his own safety. Place his twin sister, who can’t yet crawl, in the same spot and she will be curious but unafraid. Without having experienced mobility (and falling down, which quickly improves depth perception), she doesn’t know enough to be afraid. (Note that neither infant knows enough about Plexiglas to know to not be afraid.)
But until relatively recently, language has served as an exception. Sure, we have to learn language from the world, and yes, our day-to-day experiences lead some of us to say Fire in the hole! considerably more often than others. But though shaped and triggered by the world, language itself has largely been considered independent of the world, an abstraction, the crown jewel of the provinces of the mind.
This is changing. Psychologist Rolf Zwaan and his colleagues presented undergrads with sentences such as He hammered the nail into the floor or He hammered the nail into the wall. Immediately after reading a sentence, participants saw a line drawing of an object (e.g., a nail) on a computer screen and were asked to decide as quickly as possible whether the object had been mentioned in the sentence they’d just read. For half of the participants, the nail was drawn vertically, and for the other half it was drawn horizontally. When the vertical nail was shown, participants were faster to verify that it had been mentioned when the preceding sentence was He hammered the nail into the floor, and when the horizontal nail was shown, participants were faster to verify its mention when the preceding sentence was He hammered the nail into the wall. In short, when the nail’s orientation in the drawing matched its orientation in the sentence, participants had an easier time with the task. Similarly, Zwaan and colleagues asked participants to name an object (e.g., to say “eagle” when presented with a picture of an eagle) after reading either the sentence The ranger saw the eagle in its nest or The ranger saw the eagle in the sky. Participants who read the first sentence were faster to say “eagle” when it was pictured with its wings folded, and those who read the second were faster to say “eagle” when it was pictured with its wings outstretched.
Studies such as these have convinced a growing number of psychologists that perception is more closely tied to language than once thought, and some have gone so far as to deem perceptual representations the “building blocks” of cognition. In order to understand He hammered the nail into the wall, these researchers argue, we actually (somewhat unconsciously) simulate the experience of hammering a nail into a wall. We may not move our forearm or see a nail, but our mind churns through the relevant motor and sensory processes all the same.
Not everyone is thrilled with this line of thinking. A big concern is whether mental simulations are needed to explain the data. When we hear the word “tough,” we rarely (if ever) actually think “Plexiglas.” So many other things are also tough that this would be impractical, if not impossible. But when we hear the two words together, we understand that they are a better match than, say, “weak” and “Plexiglas.” Likewise, the participants in Zwaan’s experiments may not have been mentally re-creating an eagle taking flight when reading a sentence about an eagle taking flight: they may have simply, upon seeing the picture, been able to use the better match between sentence and picture to speed their understanding of the latter. But the simulation camp has some tantalizing neurological evidence in its corner. Imaging data suggests that some of the same parts of the brain become active when thinking about sitting in a chair as when actually sitting in the chair. Indeed, simply saying the word “kick” is enough to activate the parts of the motor cortex associated with the movement of the legs. So, as strange as it seems, the mind may soon bequeath its crown jewel to the body.
Jessica Love recently received a Ph.D. in cognitive psychology and is currently a science writer and editor at Northwestern University.