by Sian Beilock
It’s a standard view that we scientists always conduct a little bit of “me-search” in what we do, and I absolutely want to explore the mind-body connections I have experienced firsthand. As an example, a few months ago I went to pick up my two-year-old daughter, Sarah, from preschool. I immediately noticed she wasn’t her happy self, and my maternal alarm signal went off when she asked for some medicine. Was she sick? I checked her forehead, but she didn’t feel overly warm, so I asked her what was wrong. Did her tummy hurt, or maybe she had a sore throat? But neither seemed to be the case. After some more questioning, and a short conversation with one of Sarah’s teachers, I got to the bottom of things. Apparently one of the boys in her class had taken a toy from her that she really wanted to play with. He was so mean about not sharing that Sarah had started to cry. Sarah remembered that she took Tylenol when she had a fever and didn’t feel well and that taking the medicine usually made her feel better. It was a short leap for her to the idea that the Tylenol would make her feel emotionally better too.
I got to wondering whether Sarah’s line of thinking might have some merit, especially since my team had recently discovered that, in the brain, being mentally anxious (say, about doing math) looks a lot like experiencing physical pain. Sure enough, I found research by the husband-and-wife team of Naomi Eisenberger and Matthew Lieberman at UCLA that a daily dose of Tylenol diminishes the hurt feelings that often accompany being socially teased, spurned, or rejected—or getting a toy taken away.20 Tylenol reduces the sensitivity of the neural circuits involved in pain, so it has the power to lessen both social and physical pain. I wondered if this might work for math-anxious folks too, and, in future research, intend to find out.
Our thinking extends beyond the cortex. My new goal, as both a researcher and a layperson, is to find out just how far this new science of embodied cognition can take us in finding the ingredients we need to function at our best.
CHAPTER 2
Act Early, Think Better Later
Seen from the outside, the Breslin family seems to be living the American dream. John Breslin has a successful orthodontics practice in downtown Chicago, and his wife, Amy, is a stay-at-home mom with a master’s degree in early childhood education. They have two beautiful children, Logan, age nine, and Olivia, six. But from very early on, Amy and John had a feeling that there was something not quite right with Olivia.
Amy’s pregnancies with both her kids hadn’t been easy. She had the typical nausea and tiredness, but her exhaustion went beyond what most women describe. She had looked with amazement at other pregnant women who were excited and bubbly and seemed to float effortlessly down the street, unable to understand how they could feel so good when she was totally worn out. While pregnant with Logan, Amy had been worried that her discomfort might be a sign that something was wrong, but Logan was born at forty weeks, like clockwork, a beautiful, healthy, eight-pound baby boy. His Apgar score, the test used to assess the health of newborns, was a 9 out of 10. One of the nurses told Amy jokingly that only pediatricians’ kids get a 10 out of 10. Now Logan was into sports, the outdoors, and of course anything with a computer screen.
Because of her experience carrying Logan, Amy dismissed the difficulties of her second pregnancy, thinking the discomfort was normal for her. However, a bad case of the flu at sixteen weeks concerned her. The virus put Amy out of commission, giving her a fever of 102 on and off for several days in a row. Her doctor reassured her that the fever wouldn’t cause any complications for the baby. But how could she be sure?
After the flu, things went as well as Amy had come to expect. And, to the Breslins’ relief, Olivia was born right on time. Their relief was short-lived, however, as it soon became clear that their bright-eyed baby girl was a major handful.
To say that Olivia was colicky, crying for no reason, just doesn’t capture the first few months of her life. She cried and cried, a sharp and piercing cry that scared her parents. Olivia didn’t like to be put down in her bassinet—or anywhere, for that matter. She had trouble falling asleep, and nothing seemed to make her happy. But Olivia’s pediatrician wasn’t concerned, saying Olivia was just fussy and would grow out of it.
But when Olivia began missing her motor milestones, there was no way to ignore the signs that something was wrong. Around three or four months of age, when babies are put on “tummy time” and start to lift their head, Olivia just lay there, hardly moving. She couldn’t keep her head up very long, as if it was too heavy for her body to support. She didn’t start to roll over on her own until she was close to ten months old, and she was slow to sit up and slow to walk. It was as if all the other babies around her age had learned to climb to the top of the jungle gym and Olivia hadn’t even figured out that there was a playground.
At some point Olivia’s pediatrician tested her for seizures, strokes, cerebral palsy, and many other syndromes, but a neurologist Amy and John had been referred to finally made the diagnosis of developmental dyspraxia when Olivia was around nineteen months old. An impairment in the organization of movement, developmental dyspraxia is usually thought to be due to slow or altered brain development, but its exact causes are unknown.
Amy and John were actually quite relieved when they received Olivia’s diagnosis, thinking it wasn’t as bad as a terminal disease and would just make her a little slow on the playground. But developmental dyspraxia isn’t just about having poor athletic abilities; it’s a mind-and-body learning disability. Olivia couldn’t hold a crayon, and it took her several tries to open a book. All those activities that other kids learned easily—shoe tying, teeth brushing, using a spoon—Olivia did not. She was also slow to speak and had trouble understanding what others said to her. Motor problems have consequences way beyond being able to catch a baseball. They go hand in hand with mental difficulties too.1
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About the same time that Olivia’s difficulties were convincing her parents of just how closely connected the body and mind are, some four thousand miles across the Atlantic Ocean a group of neuroscientists at the University of Parma in Italy studying monkeys’ brains made a discovery that brought them to the same conclusion. The discovery had to do with neurons, the individual nerve cells, in an area of the brain known as the premotor cortex, whose sole function, neuroscientists had assumed for years, was to coordinate bodily movements like reaching for your keys or grabbing a mug of coffee. What the Italian neuroscientists found, however, was that these premotor neurons in primates’ brains became excited not only when the monkey moved, such as when he reached for an apple, but also when the monkey saw someone else reach for an apple. Just watching someone else perform an action caused the monkey’s motor cortex to fire as if he were doing the action himself.
Professor Giacomo Rizzolatti and his graduate students actually came upon this finding by accident. They had been conducting a typical neurophysiology experiment, recording electrical activity from neurons in a rhesus monkey’s brain. The scientists had cut a small hole in the monkey’s skull so that they could implant tiny electrodes inside. In this particular study, the tips of the electrodes were placed in individual nerve cells in the premotor cortex. Given that the premotor cortex was known for choreographing movement, the scientists weren’t surprised to find that when the monkey reached out and grabbed a peanut and put it in his mouth, the neurons they were measuring turned on. Satisfied with what they were observing, the researchers went to lunch, leaving the monkey wired up in his chair.
When one of the graduate students returned from lunch eating a gelato right in front of the monkey, the electrodes emanating from the animal’s cortex signaled that his premotor neurons were firing. The monkey’s motor neurons were sensitive to the actions he was observing, even though the monkey himself was completely still!2
The discovery of these aptly named “mirror neurons,” which fire both when an action is produced and when someone is seen performing the same action, point to how our close primate relatives might come to understand the behavior
of others.3 By mentally mirroring the actions he is viewing, as if he were performing them himself, the monkey is able to understand others’ goals and intentions. It wasn’t such a leap to conclude that humans’ ability to decipher other people’s actions, intentions, and even feelings might work in a similar way. We understand others by replaying their behavior in our own motor system as if we are performing the behavior ourselves. The existence of mirror neurons means that, for our motor system to properly recognize what’s going on around us, it helps to be able to enact the behaviors we observe. This is not such good news for a child such as Olivia, however, given that her developmental dyspraxia hinders her ease of acting. If she can’t fire up her own motor system to produce fluent bodily movements, she’s likely to have trouble understanding the actions and intentions of others.
For years brain scientists have assumed, like Descartes, that mind and body are largely separate entities. But the discovery of mirror neurons in the monkey’s premotor cortex paints an entirely different picture of the mind-body connection. Instead of seeing the body as a passive vehicle that the mind puts to use, we now realize that our body and its experience acting in the world influence the contents of our mind in unexpected ways. Being able to perform an activity—whether it’s eating, brushing our hair, or throwing a ball—gives us the ability to recognize what others are doing and, more important, why they are doing it.
Of course, other twentieth-century scientists had begun looking at the body’s intelligence before the mirror neuron discovery. In the 1960s the Swiss philosopher and psychologist Jean Piaget argued that body movements served as a foundation of knowledge.4 Piaget believed that babies possess “sensorimotor intelligence,” which means that their actions help them form ideas about the world. Infants don’t differ from adults simply because they have less knowledge or lower brain-processing power, Piaget pointed out, but because they haven’t yet spent as much time interacting with their surroundings. The contents of infants’ thoughts are actually different from those of adults. Einstein said that Piaget’s idea that children have their own special kind of logic is “so simple that only a genius could have thought of it.”5
One of Piaget’s insights about the strong connection between moving and understanding came when he saw his seven-month-old daughter, Jacqueline, drop a plastic duck she was holding onto the blanket she was playing on. The toy landed in a fold in the blanket so she could no longer see it. Jacqueline had seen the toy drop, and it was still within her tiny arm’s reach, but she made no attempt to recover it. Curious, Piaget put the duck in front of her; then, just as she was about to grasp it, he slowly moved it from her view. Though she clearly saw him hide the duck, she made no attempt to retrieve it. Jacqueline was quite captivated by the duck, but the instant the toy disappeared, she acted as if it had never existed. Out of sight really meant out of mind.6
From his interactions with Jacqueline and his observations of other children, Piaget concluded that infants don’t understand that objects continue to exist when they themselves can’t see them. Piaget believed that children learn this notion of “object permanence” only as they gain experience interacting with the world themselves. Though more recent research has poked holes in some of Piaget’s claims, 7 his belief in the power of action was spot on. Our actions help cue our minds about how the world works and why people tend to act in particular ways.
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A typically developing toddler travels about forty-seven football fields a day and accumulates an average of seventeen falls an hour,8 giving him a ton of experience navigating the world. It’s pretty easy to disregard crawling as insignificant, but it is hugely important to a baby’s physical and mental growth. One reason is that crawling is not such an easy thing to do. As Steve Pinker writes in The Language Instinct, the motor abilities of children—whether crawling, walking, or even grabbing a pencil—are “some of the hardest engineering problems ever conceived.”9 We can teach a computer to play chess against the greatest minds of our time, but getting one to walk or crawl as effectively as a human child is still a challenge. More important, the movements of a toddler tell us a lot about how physical coordination relates to mental dexterity.
Take an experimental setup known as “the visual cliff.” It’s the baby version of base jumping, where people jump off a cliff with only a parachute on their back. Of course, the baby doesn’t have a parachute and there isn’t a real cliff, but the infant doesn’t know this. Here’s how it goes: A baby is placed on a large, plexiglass-topped table. Half of the table has a checkerboard pattern just underneath the surface, making it appear safe to crawl on. But the other half of the plexiglass is clear, giving the illusion that the tabletop falls away in a “visual cliff.” It’s perfectly safe for the baby to proceed, but the baby isn’t so sure. The problem from the baby’s perspective is that there is a cool toy on the other side of the visual cliff that she desperately wants. What’s a baby to do?
Some babies avoid the visual cliff, while others crawl heedlessly forward. Who are these little risk-takers, and what makes them so different from their more cautious counterparts? As it happens, the infants who crawl straight over the apparent cliff are the more inexperienced crawlers. Babies who have been crawling a lot longer avoid the cliff; their experienced motor system emits signals warning that the drop-off might not be safe.10
Interestingly, even babies who avoid the visual cliff when crawling often wheel right over the edge without a moment’s hesitation when they are in a walker that allows them to scoot around with their feet on the floor.11 They are expert crawlers, but not expert walkers, so their motor system doesn’t send out a warning that walking over the edge of the cliff won’t be safe. This is one reason why baby walkers are so dangerous: they allow mobility beyond babies’ bodily capabilities, and, as a result, the infants don’t learn to predict the outcome of their actions. Babies in walkers tend to go right over visual cliffs—like the stairs in their house.
In the mid-1990s, when baby walkers were at the height of their popularity in the United States, the Consumer Products Safety Commission reported that walkers were responsible for more injuries (broken bones, chipped teeth, head injuries, and others) than any other baby product in circulation. In 2004 Canada banned baby walkers; possession can lead to fines up to $100,000 or six months in jail.12 Not only are walkers dangerous, but they actually retard motor development. Babies who spend a lot of time in walkers don’t learn to stand by themselves as soon as they normally would and have a harder time walking unaided because they are used to having their weight supported by the device. Indeed, delays caused by the baby walker are striking: every twenty-four hours of total walker use is associated with delays in walking alone of about three days and delays in standing alone of almost four days.13
Diapers can also hinder motor development. Walking is difficult for babies, but it’s even harder when you have to wear a bulky diaper between your legs. Old-fashioned cloth diapers are especially disastrous for walking because the bulk causes babies to take wider, bowlegged steps, but even modern disposable diapers that are designed to be thin and light can adversely affect gait. When wearing a diaper, babies fall more and look more awkward when walking.14 When infants are naked, they walk better. Yet we hardly give them any time to run around in their birthday suit. In one study of diaper use, infants just over a year old averaged only forty-one minutes of naked walking per week; a third of the babies never walked naked.
How babies move affects their cognitive functioning too. Nine-month-old infants who can crawl have better memory than their same-age counterparts who don’t yet locomote freely on their own.15 The more infants explore their surroundings, the more practice they get using their memory about one situation to guide their actions in new surroundings. Continuously flexing their mind in this way endows infants with sharper thinking skills. In contrast, baby walkers have been linked to delays in hitting cognitive milestones, such as interacting with a caregiver and understanding the thoughts and i
ntentions of others. These delays in mental development are still present almost a year after walker use has ceased.16
Information doesn’t travel in only one direction, from thought to action; action also creates thought. Not only do babies come to understand by experience how objects work and where it’s safe to walk, but their mental skills, such as understanding others’ intentions, thoughts, and feelings, also come from being able to act on their own in the world.
Simply put, babies understand others’ intentions much better when they can do what they are seeing others do. Think about reaching out for an object: what exactly we reach for tells others something about our intention. Do we want to pick up a book or a stuffed bear or a ball? If these toys are all in the same toy box, it’s basically the same movement to reach each one, but the intention is different. Babies come to realize this only when they can pick up toys themselves. It seems obvious to you and me, but not to a three-month-old. Babies who can’t yet reach out and grab objects on their own aren’t as adept at noticing when a person switches from grabbing one toy to grabbing another. Babies need the opportunity to pick up the toys themselves. Wearing a pair of “sticky mittens,” which have Velcro on the palm, lets them easily pick up toys by swiping or batting at them. All of a sudden they start to notice when someone picks up a new toy.17 Like a light switch shifting from the “off” to the “on” position, infants’ experience of reaching and grasping for toys infuses their tiny premotor cortex with the ability to notice someone else’s goals. As with the rhesus monkeys in Rizzolatti’s experiments, the human babies are able to mirror the actions of others and understand others’ intentions because they have experience interacting with the toys themselves. This is why Olivia Breslin, the six-year-old with developmental dyspraxia, is having a hard time understanding what others are doing: she herself can’t do the things she is observing.