A mark on a page, an online meme, a fleeting sound. How can these seemingly insignificant stimuli lead to acts as momentous as participation in a racist rally or the massacre of innocent worshippers? Psychologists, neuroscientists, linguists and philosophers are developing a new theory of language understanding that’s starting to provide answers.
Current research shows that humans understand language by activating sensory, motor and emotional systems in the brain. According to this new simulation theory, just reading words on a screen or listening to a podcast activates areas of the brain in ways similar to the activity generated by literally being in the situation the language describes. This process makes it all the more easy to turn words into actions.
Simulations are step one
Traditionally, linguists have analyzed language as a set of words and rules that convey ideas. But how do ideas become actions?
Simulation theory proposes that processing words depends on activity in people’s neural and behavioral systems of action, perception and emotion. The idea is that perceiving words drives your brain systems into states that are nearly identical to what would be evoked by directly experiencing what the words describe.
Consider the sentence “The lovers held hands while they walked along the moonlit tropical beach.” According to simulation theory, when you read these words, your brain’s motor system simulates the actions of walking; that is, the neural activity elicited by comprehending the words is similar to the neural activity generated by literal walking. Similarly, your brain’s perceptual systems simulate the sight, sounds and feel of the beach. And your emotional system simulates the feelings implied by the sentence.
So words themselves are enough to trigger simulations in motor, perceptual and emotional neural systems. Your brain creates a sense of being there: The motor system is primed for action and the emotional system motivates those actions.
Then, one can act on the simulation much as he’d act in the real situation. For example, language associating an ethnic group with “bad hombres” could invoke an emotional simulation upon seeing members of the group. If that emotional reaction is strong enough, it may in turn motivate action – maybe making a derogatory remark or physically lashing out.
Although simulation theory is still under scientific scrutiny, there have been many successful tests of its predictions. For example, using neuroimaging techniques that track blood flow in the brain, researchers found that listening to action words such as “lick,” “pick” and “kick” produces activity in areas of the brain’s motor cortex that are used to control the mouth, the hand and the leg, respectively. Hearing a sentence such as “The ranger saw an eagle in the sky” generates a mental image using the visual cortex. And using Botox to block activity in the muscles that furl the brow affects the emotional system and slows understanding of sentences conveying angry content. These examples demonstrate the connections between processing speech and motor, sensory and emotional systems.
Recently, my colleague psychologist Michael McBeath, our graduate student Christine S. P. Yu and I discovered yet another robust connection between language and the emotional system.