How the Body Knows Its Mind_The Surprising Power of the Physical Environment to Influence How You Think and Feel

by Sian Beilock

  CHAPTER 6

  Shoes, Sex, and Sports

  USING OUR BODY TO UNDERSTAND OTHERS

  Mind Reading

  Since the time of Aristotle, philosophers have argued about whether the location of our mental abilities is the head or various other parts of the body, such as the heart. Franz Joseph Gall, a nineteenth-century German philosopher of medicine, developed cranioscopy, or phrenology, believing he could study what was going on inside a person’s mind by looking at the shape of her skull. Gall argued that different parts of the brain carried out distinct mental processes—for instance, feelings of self-esteem, hope, and language—and that the subtle differences in the shape of the skull under which different parts of the brain lay could be used to infer attributes such as intelligence and moral character. As his work became accepted, it wasn’t uncommon for job applicants to be sent to the local phrenologist to have their skull read as part of the hiring process, so that employers could expect their new employees to have intact concentration and conscientiousness modules.

  Gall published his tome on phrenology in 1819. The English translation of the title is The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular, with Observations upon the Possibility of Ascertaining the Several Intellectual and Moral Dispositions of Man and Animal, by the Configuration of Their Heads. This title would never fly today—it’s way too long to Tweet!

  In the early 1800s a lot of people believed phrenology to be a true window into the mind.1 The Church, however, rejected the idea that there were physical manifestations of traits such as hope or self-esteem. Others called it “bumpology,” mocking the idea that one could intuit the contents of a person’s mind from the shape of her skull. Scientists called the work pseudoscience and accused Gall and his followers of looking exclusively for evidence that confirmed their beliefs and ignoring findings that didn’t.

  The phrenology movement was rife with what psychologists today call “confirmation bias.”2 Even though it’s no excuse, it’s actually quite easy to fall into a confirmation bias trap. Allow me a short digression to prove the point. Take a look at the following word problem:

  You are given four cards with “A,” “D,” “4,” “7” on one side and a rule: “If a card has a vowel on one side, then it has an even number on the other side.”

  Your job is to test this rule to determine if it is valid. The question is: Which cards do you need to turn over to determine if the premise holds?

  If you picked cards “A” and “4” you are in good company. Many people do this, but, like phrenologists, you are falling prey to confirmation bias. You do need to turn over the “A” card to see if the rule holds—there should be an even number on the other side—but it doesn’t matter what is on the other side of the “4” card. There was no rule about cards with consonants on them. Perhaps they too have even numbers on the other side. What you need to do, and what most people fail to do, is to try to disconfirm the rule. To do this, you have to turn over the “7” card. If this odd-number card has a vowel on the other side, then the rule can’t be true.

  Most people don’t go around looking for information that disconfirms their beliefs. And, this was certainly true for phrenologists. However, by the mid-1800s the lack of rigor in phrenology’s claims became clear, and its popularity waned.

  Not all of Gall’s premises were completely off base. Modern neuroscience has certainly found evidence for specialization of brain function. Language, for example, appears to have some fairly localized centers in the brain. Using techniques such as fMRI, scientists are able to peer inside people’s brain while they are speaking and have confirmed that distinct neural real estate is devoted to communicating with others and understanding what they say. Yet through this work, neuroscientists have also come to realize that the meaning of what we process is not limited to one piece of brain tissue but is distributed throughout the brain. For example, when we need to understand language about the world, we call upon the parts of the brain that support our actions and interactions—even when we aren’t physically moving at all.

  You may have heard the phrase “Cells that fire together, wire together.” It’s the simplified version of biologist Donald Hebb’s striking discovery in 1949 of how malleable the structure of our brain is. Hebb found that brain cells that are repeatedly active around the same time tend to become “associated.” In other words, activity in one neuron helps bring about activity in the other. Known as Hebbian learning, as cells excite one another over and over again, there is some growth or metabolic change across the connections between the cells that makes the cells more efficient at triggering each other. In the context of ascribing meaning to language, when a word is frequently encountered in the context of a particular action, hearing the word triggers activity in motor areas of the brain, which helps give rise to understanding. We understand many utterances because motor areas of the brain that would be used to do what we are hearing about get involved in making meaning out of the sounds.

  This is certainly true for simple verbs such as lick, kick, and pick. Understanding their meaning isn’t driven by a language minicomputer located deep inside the brain that makes sense of these words all on its own. The actual areas of the brain used to enact the body movements are also important. To understand these verbs we exploit the motor areas of the brain we use to perform these actions.3 The word grasp gets its meaning because we can associate it with the grasping movements we perform; the association of the verb give with the act of giving grounds the meaning of this utterance in action. Even when you talk about something abstract, such as giving your boss an idea, the motor systems that control handing an object to someone get involved.4

  You can think of language understanding as a mental simulation of action, using many of the same brain systems that we use to actually act in or perceive the world. This entails that words give rise to action, but also that, when we perform actions, such as turning our hand clockwise, we have an easier time understanding sentences with these actions in them: “Jessie turned up the volume.”5 When actions and words (or even phrases) are repeatedly paired together, you can’t help but trigger one when the other occurs. And the more actions and words mingle together, the more fluent and deep is our understanding of language. Of course, this also implies that, when you have a disruption in the motor system, language—and especially language about action—will be impaired.

  * * *

  A patient was admitted to a hospital in England, in late January 2000. A few months earlier, his wife had noticed that he had become consumed with the idea that something bad was going to happen to him. At first, she didn’t think much of her husband’s paranoia because he had always been a little anxious and prone to premonitions of doom. But his delusions had worsened, and in the weeks leading up to his admittance to the hospital, he constantly worried that harm would befall him at any minute.

  The hospital has one of the best neurology units in England, and within a few hours of the patient’s arrival, a team of doctors started a general workup on him and found that his movements were slow. He was on olanzapine, an antipsychotic medication intended to control delusions; one side effect of the medication is motor difficulty, so his motor problems alone weren’t unexpected. However, a scan of the structure of his brain revealed atrophy of the frontal lobes. He performed poorly on many of the mental tests he took and was also having trouble with his speech. When given sixty seconds to name as many words as possible from a given category, such as cars or fruits or words that begin with the letter “T,” he could come up with only two or three items for each group.

  Over the next six months, the patient continued to show signs of decline. At each return visit to the hospital, he was slower than he had been the time before and his speech more slurred. At some point all he could say was “yes” and “no”; then, one day, he lost his speech completely. He was still able to communicate in a limited manner using facial expressions and gestures, but he could no longe
r talk.

  A group of neurologists at the hospital had been following patients for the past few years who had presented with very similar symptoms, and they became interested in this patient’s case. In particular, his rapid motor and language declines were characteristic of motor neuron diseases, a group of progressive neurological disorders that destroy the cells that control voluntary muscle activity involved in speaking, walking, breathing, and swallowing.6

  Usually when we want to execute a movement, a message from motor neurons in the brain is sent to the spinal cord. From there, the particular muscles necessary for carrying out an action get a directive to contract and act. When disruptions occur in these signals, the muscles don’t work properly; they slow down, accompanied by stiffening and twitching. Eventually the ability to control movement is lost altogether. This loss of movement is devastating, but the biggest problem for people with motor neuron disease is that they have difficulty swallowing. When you can’t swallow normally, it’s hard to prevent inhaling foreign substances into your airways. Patients with motor neuron disease often die from aspiration pneumonia, an inflammation in the lungs that happens when food, vomit, liquid, or spit are inhaled.

  Up to six out of every 100,000 people are affected with motor neuron diseases. The physicist Stephen Hawking has a form called amyotrophic lateral sclerosis (ALS), or Lou Gehrig’s disease. Former New York senator Jacob Javits also had a motor neuron disease.7

  Neurologists at the U.K. hospital devised a series of tests to better understand the problems of patients they suspected of having motor neuron diseases. In one test, patients were asked to match words such as shoe or eating with pictures that depicted the meaning of the words. Interestingly, patients performed disproportionately poorly on matching verbs to depictions of action.

  In another assessment, the Pyramid and Palm Trees Test, the neurologists gave patients a picture of a pyramid followed by a picture of a fir tree and a picture of a palm tree. The goal was to choose the tree that belonged with the pyramid (the palm tree). Finally, the Kissing and Dancing Test depicted actions rather than objects. Patients might see a picture of a hand writing a letter, followed by pictures of a hand typing and a hand holding a spoon and stirring coffee. Because writing is more closely related to typing than to stirring, the appropriate match here is the typing hand. There were no differences in performance across the two tests for normally aging adults. However, the patients diagnosed with motor neuron disease did worse on the Kissing and Dancing Test than the Pyramid and Palm Trees Test.

  In most languages, verbs tend to be more difficult to understand than nouns, likely due to verbs’ greater grammatical complexity. This is especially true in languages such as English and Italian and less so in languages with complex noun constructions such as Greek and the Slavic languages. However, patients with other forms of damage or degeneration to their brain (for example, Alzheimer’s disease) don’t show this special trouble with verbs; only people with motor neuron diseases do.8 Why? A possible reason is that the dysfunction of the motor system impairs not only actions but their linguistic correlate—verbs—as well. When you don’t have the systems to act properly, understanding action language is hampered.

  The patient admitted in January 2000 to the U.K. hospital died less than two years after the initial appearance of his symptoms. A postmortem examination confirmed the diagnosis of motor neuron disease. Similar to other patients who also died from the disease, the patient showed atrophy of the brain stem and spinal cord as well as a wasting away of the premotor and motor cortex.

  * * *

  Around the same time that the neurologists at the English hospital were discovering a link between language and action via their patients diagnosed with mirror neuron disease, the neuroscientist Friedemann Pulvermüller was also making important progress in understanding body language. For several years, Pulvermüller had been interested in what happens in the brain to precipitate impairments in people’s ability to speak and understand. He was particularly fascinated by the fact that the language problems that often arose in the wake of a stroke seemed to accompany impaired motor abilities.

  To understand Pulvermüller’s work, it’s important to take a closer look at the makeup of the motor system. The bit of neural tissue that is the motor cortex sits on the outside of the brain and straddles both hemispheres. Its role, at a most basic level, is to translate plans to act into actual actions. The nerve cells that innervate the motor cortex are organized in such a way that specific areas control particular body parts and more importance is given to the body parts that do the most work. For instance, the fingers, and especially the thumbs, have a disproportionately large representation in the motor cortex. Most people can flex and extend the ends of their thumbs fairly easily, but it’s a bit harder to make analogous movements with any of their other fingers. The difference is due, in part, to disparities in the amount of brain tissue devoted to the thumb and the rest of the fingers. The thumb has more neural real estate.

  It’s possible to make a map of the body by documenting the connections of particular body parts to the motor cortex. Called a somatotopic map, the resulting image looks like a disfigured human with a disproportionately big face, lips, and hands compared to the rest of the body. Because of the fine motor skills these particular parts of the body need to perform, they take up a larger part of the brain’s map.9

  Somatotopic maps were first developed in the 1950s as a byproduct of a technique used to treat epilepsy.10 At the time, a common treatment for uncontrollable epileptic seizures was to open up the patient’s skull, locate the tissue from which the seizures emanated, and destroy the nerve cells there. Before the operation, however, neurosurgeons used electrical probes to stimulate different parts of the brain while the patient was conscious on the operating table so that they could observe which parts of the brain were most in control of which functions. That way they could target areas for removal that would cause the least disruption after surgery. This stimulation technique allowed for the creation of somatotopic maps of the motor cortex, showing the brain’s connections to the rest of the body.

  Illustration of the somatotopic organization of the motor cortex.11

  These body maps help to make sense of some interesting phenomena. Ever wonder why it’s so nice to get a foot massage? It may be because the areas of the brain that represent the foot and those that represent the genitals are located close together. To the extent that being adjacent to each other tends to facilitate crosstalk among neurons, exciting one area may spill over and stimulate the other. This proximity of the brain’s areas for the genitals and the feet may also explain why some people have foot fetishes and even shoe obsessions.12 Although we will never know for sure unless Imelda Marcos donates her brain to science, it seems likely that these two regions are closely connected in the brain of the former first lady of the Philippines. Some neuroscientists have argued that the foot and genital areas on the brain’s body map are more closely related in women than in men,13 possibly explaining the female sex’s fascination with footwear.

  Pulvermüller and his research team used somatotopic body maps to study the link between language and action. While volunteers’ brains were being scanned, the volunteers were instructed to perform simple movements of the hand, mouth, and feet. The volunteers also read verbs associated with moving these body parts. Moving their limbs activated areas along the motor cortex that connected to the moving body parts, and hearing verbs related to these movements triggered activity in many of the same (or closely adjacent) brain areas. Leg areas of the motor system turned on when people heard words such as kick; arm and hand areas were activated by words like pick. Action words related to the face, like lick, activated brain areas involved in controlling tongue movements. Most striking, Pulvermüller found that motor involvement in language processing happens extremely quickly, within just a few hundred milliseconds after a word is heard. The speed of this motor activation suggests that our action systems get involved right aw
ay when we have to understand a word, in the initial meaning-making stage.14

  Pulvermüller’s discovery has important implications. For starters, it locates one neural source of understanding: the brain areas that are used to move are also used to understand language—at least verbs. As the philosopher Ludwig Wittgenstein put it, language “is woven into” actions.15 Most important, if the motor system helps give rise to language understanding, then language problems arising from, say, a stroke, might be alleviated by stimulating brain areas important for action. Repairing the motor system could actually help facilitate the recovery of language.

  An estimated 15 million people suffer from strokes each year. Sometimes called a “brain attack,” a stroke happens when blood flow to the brain is interrupted.16 Roughly one-third of stroke victims develop problems with language, called aphasia. For some people, these language problems improve over time, but many experience chronic, long-term communication impairments. Unfortunately, treatment for chronic aphasia is limited, and people usually give up therapy long before their communication problems have been solved. Pulvermüller’s work is changing this; based on his language research, he has helped pioneer a novel treatment for aphasia that is rooted in action. In his therapy, language is practiced in the context of actions. Stroke patients exercise basic as well as more advanced language skills, such as making a request or answering a question using flash card prompts as cues. The language is practiced along with the relevant actions.17 And it’s the action that seems to be doing some of the heavy lifting in helping people relearn language, even those who have had chronic aphasia for several years after a stroke. Pulvermüller’s action therapy helps the brain link language with action—processing that is often disrupted after a stroke but that we now know is imperative for understanding.