The Wall Street Journal Column

Mind and Matter

Inheriting the Trauma of Genocide

Research shows that atrocities witnessed by Tutsi survivors in Rwanda can leave marks on their children, born years later

Inheriting the Trauma of Genocide
ILLUSTRATION: TOMASZ WALENTA

By

Susan Pinker

https://www.wsj.com/articles/inheriting-the-trauma-of-genocide-11550761430

A century ago, we called it shell shock—the legacy of trauma that wrought havoc on the bodies and minds of some World War I veterans. Today, when survivors of terrible events experience flashbacks and fears that disrupt their daily lives, long after the actual threat is gone, it is called post-traumatic stress disorder, or PTSD. Whatever you call it, we now know that direct exposure to extreme deprivation, violence, dislocation or torture can transform not only those who experience it but also their future offspring.

Scores of studies have shown that the adult children of Holocaust survivors who suffered from PTSD are at high risk of developing the disorder themselves. Now, 25 years after the genocide against the Tutsi of Rwanda, an unusual collaboration between Rwandan and Israeli researchers has uncovered similar intergenerational effects. The atrocities witnessed by surviving Tutsis have left enduring marks on their adult children, the vast majority of whom hadn’t been born when the genocide took place in 1994.

The study, published last month in the journal Psychiatry Research, was led by Amit Shrira, a professor of psycho-gerontology at Bar Ilan University, working with Benjamin Mollov, a Bar Ilan social scientist, and Chantal Mudahogora, a Canadian researcher and a survivor of the genocide in Rwanda. The team studied 60 pairs of Tutsi survivor parents and their adult children, all of whom completed two questionnaires about their psychological state.

Not all families who share a brutal history are the same, the researchers discovered. According to their responses, the Tutsi parents could be divided into three groups.

The first group (33.3%) suffered from complex PTSD, a new diagnostic category that includes panic attacks, recurring nightmares and intrusive memories. They perceived themselves as helpless and had difficulty maintaining close relationships. The second group of parents (26.7%) had simple PTSD: They continued to relive the traumatic events and personal losses they had experienced and were haunted by a sense of threat. The third group (40%) didn’t have any clinical symptoms of PTSD. Though it is impossible not to experience distress after surviving a genocide, this group of parents seemed to be surprisingly resilient; their feelings of grief didn’t disrupt their lives to the degree that they merited a clinical diagnosis.

The more severe a parent’s symptoms, it turned out, the more severe were those of the adult child. “The children of parents with complex PTSD suffered the highest level of secondary traumatization, with symptoms related to the parental trauma,” said Dr. Shrira. “These children were born after the genocide, but they had nightmares about it and were more restless and hypervigilant than the children in the other two groups.”

Ms. Mudahogora noted that her own three adult children have been affected by her experience as a survivor. “I never grew up with any grandparents, so I miss that a lot,” said her son Chris Mucyo, a 23-year-old university student who was born after the genocide and participated in the study as a subject. “I have great parents, but it is a lot of pressure. We didn’t have a period of innocence as kids.”

That self-awareness is telling. Having parents who modeled coping skills while talking openly about their losses can make a big difference, said Dr. Shrira, who has observed the same resilience in the families of many Holocaust survivors. It is unclear why some survivors transmit trauma to the next generation while others do not. We know that the vulnerability of parents to trauma is likely passed on to their children through genetic and epigenetic means, but how they face adversity is also a factor, speculates Dr. Shrira. “After all, the transmission of trauma is also the way the story is told.”

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Aggression in Boys Is a Family Matter

A new study of children shows that problematic behavior can be identified in infancy, if not before, by looking at their background and circumstances

Aggression in Boys Is a Family Matter
ILLUSTRATION: TOMASZ WALENTA
By
Susan Pinker

In 25 years of clinical practice as a psychologist I’ve seen my share of aggressive boys. They ended up in my office because they kicked classmates, poked children with scissors or, in one unforgettable case, set another student’s collar on fire to get his attention. (It worked.) These boys were usually between the ages of 4 and 10, and most of them came from chaotic homes with few clear expectations, closely spaced siblings and an overwhelmed mother. The father was often absent, literally or psychologically. They had been referred by their teachers, who wanted the aggression to stop.

It was a tall order, and I was only successful some of the time. Now I know that intervention should have started much earlier. A new study published in the JAMA Network in December suggests that children who are most likely to be aggressive throughout childhood and adolescence can be identified in infancy, if not before, by looking at their family histories.

The longitudinal study, led by Richard E. Tremblay of Université de Montréal, followed the development of 2,200 randomly selected babies born in Quebec in the late 1990s, using reports from parents, teachers and the children themselves. In a previous study, the research team found that many children try to use physical force during their first two years of life, by hitting, biting or kicking others. Normally, such aggression peaks between 2.5 and 3.5 years old, and then peters out as children mature and gradually learn society’s rules for social interaction—just in time for them to enter school.

But aggression persists in a small group of children, and the study suggests that they often share a similar home environment. “Children who show problems early are from very specific families,” said Prof. Tremblay. The predictors include one or both parents having been physically aggressive as children or having failed in school. This background is likely to keep families trapped in a dysfunctional cycle. “If you’re physically aggressive and you fail in school, the likelihood of getting a job to get out of poverty is almost nil,” Prof. Tremblay explains.

“These chronically aggressive families could be identified by obstetricians.” Prof. Tremblay says, “so interventions can start close to conception. Starting that early would have a much better impact than waiting until a child is in school.” Yet most aggressive children aren’t identified until they start kindergarten. Teachers are left to wonder, “Why didn’t the parents tell me this child has a problem?”

The answer to that question is one of the study’s most intriguing findings. Unusually aggressive boys were seldom identified by their mothers early on, the researchers discovered. Even if these boys were poised to hurt others and struggle in school, they had to wait for teachers to take note in order to get assistance. In contrast, mothers are more likely to get help for girls, who at any age are far less likely to be physically aggressive than boys.

Whether due to helplessness or denial, this blind spot can be remedied. Some states already offer support such as nurse-family partnership programs, which match vulnerable first-time mothers with registered nurses who visit them up to 60 times during pregnancy and in the child’s first years of life. The nurses offer solid, nonjudgmental advice on subjects like breastfeeding, communicating and bonding with infants and, if necessary, how to quit smoking or drinking.

Through this ongoing relationship, these mothers learn how to sustain a healthy pregnancy and respond to their developing child before he becomes intransigently aggressive, not after. Prof. Tremblay thinks that is wise. “You have to invest in prevention based on the known predictors in the family, and not wait until the second, third or fourth child is born.”

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Resilient Teens in a Dangerous World

Resilient Teens in a Dangerous World

A study shows that strong executive function in the brain helps young people’s bodies resist the stress of living in a rough neighborhood

Resilient Teens in a Dangerous World
ILLUSTRATION: TOMASZ WALENTA
By

Susan Pinker

“That which doesn’t kill me makes me stronger,” Friedrich Nietzsche famously wrote. But the truth is likely to be the reverse: If an ordeal doesn’t break you, it is probably because you were stronger in the first place.

So says a paper just published in the journal Proceedings of the National Academy of Sciences by Greg Miller, a psychology professor at Northwestern University’s Institute for Policy Research, and his colleagues. By looking at the health of teenagers living in Chicago’s rougher neighborhoods, they explored why some young people are more resilient than others. Why is it that we don’t all react to adversity the same way?

The team already knew when they started that proximity to crime can damage the health of young people. On the night after a violent crime, for example, local teens’ sleep patterns are often disrupted and their cortisol levels spike, according to a study published in 2017. Even if they don’t witness it directly, many teens’ awareness of a local homicide or assault leaves a distinct biological signature in the form of an elevated heart rate and altered behavior.

These clues show that fear is literally getting under the skins of young people, engendering long-term cardiovascular risks. “Kids who live where there is violent crime have more health issues than [those] in higher income neighborhoods. But it’s not just about income. Violence per se is related to higher blood pressure, blood sugar, more obesity and all the precursors of diabetes and heart disease,” Prof. Miller told me.

Yet some children who live in the same areas seem to be shielded from crime’s corrosive effects. To find out what protects them, researchers recruited a diverse group of 218 eighth-graders in Chicago. The researchers tracked the incidence of crime in each teenager’s neighborhood by using data from local police departments. On average, the adolescents in the study lived in areas where the murder rate is 142% higher than elsewhere in the U.S.

The researchers brought the teens into the lab for two testing sessions. First, their weight, blood pressure, abdominal fat, blood insulin and glucose levels were measured—all of which can be signs of cardiovascular risk. The second time, the young people underwent brain imaging, with fMRIs to assess the strength and efficiency of certain resting state neural networks. The goal was to check for any differences between the brains of the children with cardiovascular risk factors and those of the hardier ones. Could the more resilient participants be identified by their brain scans alone?

Indeed they could. The study found that young people with a stronger, more efficient central executive network (CEN)—the brain areas that govern the regulation of emotion, and the vigilance that accompanies fear—were also the ones who demonstrated fewer cardiovascular risk factors. “We used statistical measures to rule out the effect of the family’s income, their area’s level of pollution or segregation, or the availability of fresh food,” Prof. Miller told me. “The kids with low CEN connectivity had worse cardiovascular health.”

What this means is that participants whose brains allowed them to suppress intrusive, unpleasant thoughts and to reappraise threatening events were also physically more resilient. They were thinner, with lower biological measures of stress, and their hearts were stronger.

This was an observational study, so we can’t say for certain that a teenager’s brain architecture is what’s keeping their damaging physical reactions to violence in check. Perhaps some kids are just born resilient. Their more measured cognitive response to life’s risks comes packaged with the signs of robust cardiovascular health. I wouldn’t say that these kids have all the luck, but they do seem biologically equipped to face stress with equanimity. And that’s a good start.

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When It Comes to Sleep, One Size Fits All

When It Comes to Sleep, One Size Fits All

A massive new study shows that every adult needs 7-8 hours a night, or else their cognitive abilities will suffer

When It Comes to Sleep, One Size Fits All
ILLUSTRATION: TOMASZ WALENTA

By

Susan Pinker

 

I’d always thought that our need for sleep, like our appetite for food, drink or social contact, was a personal matter: Some people need more, some need less. Age, lifestyle, work and metabolism combine to determine how much sleep a person needs to function, and if some people thrive on five hours a night and others require seven, chalk it up to different strokes for different folks, right?

Wrong. A new study of the sleep habits of more than 10,000 people around the world suggests that the amount of sleep adults need is universal. The massive survey, published in the journal Sleep, demonstrates that adults everywhere need 7-8 hours a night—no more and no less—in order to be mentally limber. When we habitually stint on those hours, higher-order cognitive processing—such as the ability to see complex patterns and solve problems—is compromised.

The lead author of the study, Conor Wild, a research associate at the Brain and Mind Institute at the University of Western Ontario, explained how a research team directed by the neuroscientist Adrian Owen recruited thousands of people for the online study. “We did a lot of social media advertising and radio interviews. And the BBC put together a two-minute spot on Dr. Owen’s sleep research,” Dr. Wild said.

This blitz prompted more than 40,000 people from 150 countries to sign up. Ultimately, two thirds of them were eliminated due to technical glitches, incomplete questionnaires, or extreme responses—such as reporting that they sleep zero hours a night, or more than 16.

The 10,886 adults who remained filled out a detailed online questionnaire about their backgrounds, medical histories and sleep patterns. How long was their average night’s sleep? How often was their rest interrupted, and how consistent were their nights?

Once their sleep habits were recorded, the participants completed a battery of 12 cognitive tests. Puzzle-like tasks assessed their spatial, verbal and short-term memories, as well as their capacity for deductive reasoning, sustained attention, planning and clear expression.

The findings that emerged were startling. Half the sample averaged less than 6.4 hours of sleep a night—a pattern that was associated with impaired problem-solving, reasoning and verbal acuity. Those who routinely slept six hours a night or less flubbed more questions based on spatial rotation or grammatical reasoning and left more tasks incomplete than those who got a full night’s rest.

Surprisingly, mere sleep deprivation—that is, one or two nights with little or no sleep—did not alter reasoning or verbal skills, though it did hobble short-term memory. This finding is reassuring, given that many professionals—think of hospital residents and airline pilots—have to make life-or-death decisions based on exactly this kind of erratic sleep schedule. If their short-term memory is compromised, they can always look up facts on their phones. But for split-second, life-changing decisions, they are on their own.

Regularly sleeping too little seems to be much more damaging than having one or two bad nights. Getting four hours of sleep or less for an extended period is equivalent to adding eight years to one’s age when it comes to test performance, the study shows—a significant decline. But a single good night can repair some of the damage: People who slept more than usual the night before they were tested ended up acing more of the cognitive tests.

So if you want to be articulate, solve a pesky problem, parallel park or organize an effective team—or even your closet—you’ll definitely need that nightly 7-8 hours of sleep.

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When a Better Neighborhood Is Bad for Boys

Research shows that when poor families move into more expensive housing, girls’ lives improve while boys’ get worse. What explains the difference?


By

SUSAN PINKER

Sept. 26, 2018 11:10 a.m. ET

See the column on the Wall Street Journal site

Imagine you’re a single mother living at or below the poverty line in a troubled neighborhood. If you want to shield your teenager from drinking and mental distress, should you try to move to a better area or stay put? The answer depends on whether your teen is a boy or a girl, according to a new paper published in the journal Addiction.

The lead author of the study, University of Minnesota epidemiologist Theresa Osypuk, investigated the drinking habits and mental health of teenagers whose families lived in public housing in the late 1990s. About two-thirds of the families were randomly chosen to receive housing vouchers, allowing them to move into better areas.

Between four and seven years later, the researchers found, adolescent girls who had moved into more expensive neighborhoods were far less likely to drink to excess than girls who remained in public housing. But boys whose families had moved binged more. This surprising finding challenges the assumption that behavioral risks increase with economic hardship and that poverty affects women and men the same way.

It all started with a controversial social experiment called Moving to Opportunity. The goal was to give the mostly female-led families living in public housing a leg-up in the labor market, not by improving their skills but by improving their housing. From 1994 to 1998, almost 5,000 low- income families in five cities—New York, Boston, Chicago, L.A. and Baltimore—were offered the chance to participate in a lottery.

Those who opted in were randomly assigned to one of three groups. The first group received a voucher that tripled their rent budget. With this windfall they were expected to move into a nicer neighborhood. A second group got the same voucher along with relocation counseling. A third was the control group: They stayed in public housing and presumably nothing would change for them.

The results were disappointing at first. To the chagrin of the policy wonks who designed the program, improving where women lived had absolutely no effect on their employment. But it had a big impact on their health. “Rates of obesity were lower, markers of diabetes were better, mental health was better,” Prof. Osypuk said.

The second eye-opener was that moving to better neighborhoods affected men and women differently. “The households were mainly led by moms, who saw mental health benefits, and their girls did, too. But the boys saw no mental health effects, or negative effects,” said Prof. Osypuk.

The key factor was how vulnerable people were before the move. Boys are developmentally more fragile than girls, with higher rates of learning and behavior problems. That’s one reason why the well-being of the boys in the voucher groups tanked, according to Prof. Osypuk. Boys who moved out of public housing not only drank more but also showed higher rates of distress, depression and behavior problems, according to a 2012 paper that she and her team published in the journal Pediatrics.

“Boys have mental health disadvantages, and the stress of moving adds insult to injury,” Prof. Osypuk said. Just when these vulnerable boys most needed predictability, their social worlds were upended. “They moved down in the social hierarchy and hung out with riskier boys,” speculated Prof. Osypuk. Meanwhile, girls who moved to better neighborhoods experienced fewer sexual stressors and adapted to their new circumstances more easily.

When it comes to moving out of poverty, it would seem that equal treatment for everyone is only fair. This research, however, hammers home the idea that one size does not fit all.

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An Unforgettable Memory Expert Muses at 100

Brenda Milner is celebrated for her insight into recollections as a feature of neurobiology; the man who could only live in the present


By

SUSAN PINKER

Updated Aug. 23, 2018 10:28 a.m. ET

See the column on the Wall Street Journal site

If you’ve ever wondered where your memory has gone, ask Brenda Milner. The British-Canadian, who just turned 100, was one of the first researchers to discover how memories are stashed in the brain. Having spent the last 68 years investigating how we consolidate new knowledge, you could say that she knows a thing or two about remembering.

Dr. Milner began her career as one of a handful of women admitted to study mathematics at Cambridge University in 1936. Her determination was evident even then. “Cambridge was associated with mathematics and physics—you know Isaac Newton went there. That’s where I wanted to

go and nowhere else,” she told me in 2007 (I recently interviewed her again by email).

This tenacity served Dr. Milner well when she moved from crunching numbers at the British Defense Ministry to Montreal in 1944, to pursue a Ph.D. in psychology. There she worked with the neurologist Wilder Penfield at McGill’s Montreal Neurological Institute. Their research on the post-surgical brain function of epileptic patients led her to reject the then-fashionable theories that memory was a product of Freudian urges or behaviorist stimulus-response chains. Her key insight was to see memory as a feature of human neurobiology.

Dr. Milner is now considered one of the founders of cognitive neuroscience, which links the mind—perceiving, thinking, remembering—to the brain. One of the current leaders in the field, Michael Gazzaniga of the University of California, Santa Barbara, calls her “a true pioneer.”

When she started in the 1950s, the only way to localize mental activity was to see what had changed after injuries or surgery. One patient was Henry Molaison, a 24-year-old

from Connecticut who suffered from debilitating epilepsy. H.M., as he was known until his death in 2008, underwent surgery to remove parts of his temporal lobe—including his hippocampus—which the doctors thought to be the locus of his seizures.

Dr. Milner tested his cognitive function after surgery and in a 1957 paper described what happened next. Though H.M.’s personality and intelligence seemed unchanged “there has been one striking and totally unexpected behavioral result: a grave loss of recent memory. After the operation this young man could no longer recognize the hospital staff nor find his way to the bathroom.” H.M. remembered events from his distant past and with practice could learn new motor skills, but without his hippocampus, any novel experience—who he just met or what he ate for lunch—never jelled into a long-term memory.

H.M. was forced to live in the present, which despite its Zen billing, had its downsides. He had to learn of his father’s death over and over again. Each time he grieved anew. Ultimately he kept a reminder in his pocket as a form of self-protection.

By showing how distinct types of memory are stored in different brain systems—how to ride a bike or sing a Broadway tune is stored differently than the name of your third-grade teacher—Dr. Milner revamped neuroscience’s atlas of

memory. Knowing how to do something does not require the hippocampus. Knowing that you’ve learned something does.

Dr. Milner still goes to the lab a few days a week. Though most people associate her with H.M., she is “more excited about my frontal lobe work,” which helped to define the seat of self-control, planning and decision-making.

“Brain imaging is a huge thing,” she said in a recent email, when I asked what had changed in 60 years. “Back then, you had to wait until the subject died because the only way to see the brain was to dissect it.” Now you can assess healthy young adults. “To see the brain images of a living person while testing them is extremely exciting.” After all, she added, “we all go downhill after our mid-40s.”

Clearly, Brenda Milner is the ultimate exception to that rule.

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Kids Today Are Actually More Patient Than Kids 50 Years Ago

Research shows that today’s children can control their impulses better than earlier generations. What’s changed?


By

SUSAN PINKER

July 11, 2018 1:25 p.m. ET

See the column on the Wall Street Journal site

Kids today. The phrase is usually followed by eye-rolling and words like self-absorbed, impatient and entitled. But the idea that today’s children need immediate gratification turns out to be wrong. In fact, research published last month in the journal Developmental Psychology shows that they are much more patient than kids were 50 years ago.

Yes, you read that correctly. Twenty-first century children are able to wait longer for a reward than children of the same age a generation ago, and a generation before that. The new study shows that today’s preschoolers are better at what psychologists call self-regulation, which is the conscious control of one’s immediate desires—the ability to hold off and wait until the time is right.

Stephanie Carlson, the lead author of the paper and a professor at the University of Minnesota’s Institute of Child Development, knows that her findings will come as a surprise: “The implicit assumption is that there’s no way that kids can delay. They’re used to being gratified immediately and don’t know what it’s like to be bored anymore.”

But faithful re-enactments of the famous “marshmallow experiment” have upended that notion. The experiment was first designed in 1968 by Walter Mischel of Stanford University, with the participation of 165 children between ages 3 and 5 who were attending the university’s Bing Preschool. The set up was simple: Each child was left alone in a quiet room facing two plates of goodies. One plate held a single treat—one Oreo cookie or one marshmallow, for example—while the other plate had two.

The children were then told that the adult needed to leave “to do some work” but would return immediately if the child rang a bell. If that happened, the child was allowed to eat one treat. But if the child waited until the adult came back without being summoned, they could eat the larger portion. Watching through a one-way mirror, the experimenters saw whether the child licked or ate the treats while they waited, or controlled themselves until the researcher returned.

According to Dr. Carlson’s new paper, the same experiment was replicated in the 1980s, with 135 children attending the Toddler Center at Columbia University, and once again in the 2000s, with 540 children at preschools associated with the University of Washington and the University of Minnesota. As it turns out, preschoolers in this millennium were able to wait about seven minutes on average, one minute longer than preschoolers in the 1980s and two minutes longer than children in the 1960s. Over a span of 50 years, children of the same age were essentially getting better and better at controlling their impulses.

What accounts for this surprising development? “We’re trying to understand what changed…so that kids of similar backgrounds have increased their ability to delay gratification, despite expectations,” Dr. Carlson said. Improvements in nutrition and GDP might have had the effect of expanding children’s opportunities and cognitive horizons.

Parenting has also evolved. Contrary to popular belief, parents are spending more time interacting with their children than they used to. In the mid-60s, parents spent an average of 36 minutes a day teaching and playing with their children. By 1998, that figure had more than doubled, to 78 minutes a day. Parents have also become more focused on cultivating a child’s ability to make decisions for themselves. Perhaps most important is that, compared with 1968, many times more 3- and 4-year-olds are in preschool, and their teachers are better educated than ever before.

Important questions remain about the study’s findings. The children at the university preschools were mostly from white, educated, middle-to-upper class families. Their self-control is getting better all the time. But it remains to be seen if children from other backgrounds are also learning the crucial lesson that good things come to those who wait.

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New Skills Build New Brain Architecture, Research Shows

The brain’s structure can change when human beings—in this case, dyslexic children—learn a new ability


By

SUSAN PINKER

June 14, 2018 12:27 p.m. ET

See the column on the Wall Street Journal site

The latest tools of neuroscience allow us to witness, as never before, the electrical flares, chemical landslides and sluicing of water from zone to zone that alter the geography of the brain as it changes.

Evidence of the ways neural tissue is partially destroyed after a stroke or the onset of dementia has been around for decades. But proof that missing or miswired human brain connections can grow again—what neuroscientists call plasticity—has so far been thin on the ground. In 2014 a study showed that for mice, novel experiences prompt almost immediate changes in white matter—the brain’s connective tissue, or highway system.

Does this structural transformation linked to learning a new skill hold for humans too? The answer appears to be yes. A study just published in the journal Nature Communications found distinct shifts in brain architecture that mirrored the growing reading skills of children with dyslexia.

“The way the connections between different brain regions had changed was startling,” said Jason Yeatman, an assistant professor at the University of Washington who led the study.

Dr. Yeatman’s team, including postdoctoral student Elizabeth Huber, began by recruiting 24 dyslexic children, ages 7 and 12, who had been struggling to learn to read. Few of them could decipher more than simple three-letter words, which largely excluded them from the classroom experience, said Dr. Yeatman.

The researchers thoroughly tested the children’s reading skills and assessed their brain architecture using diffusion magnetic resonance imaging. This noninvasive type of brain imaging tracks how quickly water flows among regions of the brain. It provides a measure of brain density, which increases with the formation of new brain cells, connections and membrane

The children’s initial MRI was followed by three subsequent imaging sessions, evenly spaced over the course of their participation in an intensive, eight-week summer reading program. Designed by the Seattle-based tutoring company Lindamood-Bell, the program provided one-on-one instruction for four hours a day, five days a week. Unlike much recent research on children’s learning, the instruction was in person, not screen-based.

The results showed significant improvement in reading skills—and as the children’s reading fluency increased, large tracts of the white matter in their brains were visibly revamped. “It was not known before that the physical structure and efficiency of the brain could change in just a few weeks,” said Dr. Yeatman.

The instructional approach was, by design, highly individualized and interpersonal. It targets the building blocks of reading and is intended to give children with dyslexia the tools they need to read. But it is just one of several evidence-based, effective approaches. In the future, the researchers hope to compare it to other reading programs to see which features of a curriculum are critical to stimulating rapid changes in white matter.

“It was not known before that the physical structure and efficiency of the brain could change in just a few weeks,” said Prof. Yeatman. “That was one surprising thing.” Another was that the renovation was so pervasive. The researchers expected the observed improvement in the brain’s language areas. “But we also saw changes in the corticospinal tract,” which allows sensation and movement to be sensed by the brain, Dr. Yeatman added.

Perhaps the bond between teacher and child or the frequency and intensity of the teaching program made the difference. It’s hard to pinpoint the cause—or to know how long the neural and behavioral changes will last. But the changes were still impressive.

“We knew it was possible for the brain to change in mice, but we didn’t know the time frame, and we didn’t know how extensive the remodeling was in humans,” said Dr. Yeatman. Now we know that education can physically alter the brains of mice and men—or, more important, boys and girls.

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Smiles Hide Many Messages—Some Unfriendly

Faces that mean domination, reward or just ‘I want to get along with you’


By

SUSAN PINKER

April 5, 2018 10:20 a.m. ET

See the column on the Wall Street Journal site

 

Smile while your heart is breaking, put on a happy face, say cheese. We’re so used to smiling on demand that to do otherwise can seem antisocial. Even going through the motions of a smile, scientists have found, can make us feel happy.

But smiles take many forms, and not all of them sound a single, upbeat note. According to recent research, smiles are more like Morse code, silently broadcasting distinct, nuanced messages. A smile might be signaling “Do that again” (reward), “I want to get along with you” (affiliation) or “I’m No. 1 around here” (dominance). Most of us receive these nonverbal signals loud and clear; they register in the chemical cocktail infusing our saliva and the thrum of our heartbeat, says a study published last month in the journal Scientific Reports.

“Different smiles have different impacts on people’s bodies,” said Jared D. Martin, a doctoral student who led the study in the lab of University of Wisconsin psychology professor Paula Niedenthal, working in collaboration with Eva Gilboa-Schechtman of Israel’s Bar-Ilan University. Along with poker players, psychologists have long known that our facial expressions can betray our emotions. But no one has demonstrated exactly how this works, Mr. Martin said.

To explore whether certain types of smiles provoke distinct physiological responses, Mr. Martin’s team set up an experiment based on public speaking. Research shows that most people would rather get zapped with an electric shock than give a five-minute speech about themselves. It’s a handy way to examine how our bodies register stress. So in this experiment, 90 healthy male undergraduate students delivered three spontaneous speeches about themselves, each to an audience of one. The listener smiled away on Skype while they were talking.

That listener was supposedly chosen randomly but in reality was a plant trained to smile in one of three ways during the other’s short spiels: to signal reward, affiliation or dominance. The dominance smile is mildly lopsided, with closed lips and one or both eyes squeezed shut, whereas reward smiles show upturned lips exposing a row of teeth and crinkled eyes. Affiliation smiles feature pursed lips, the whites of the eyes and raised eyebrows.

The research team measured the impact of these three types of smiles by continuously monitoring the speaker’s heart rate and periodically assessing his salivary levels of cortisol, a hormone often used as a marker of stress.

The researchers found that there was eight times as much cortisol in the saliva of students facing a dominance smile as in those facing affiliative smiles and 16 times as much as in those facing reward smiles.

There were also intriguing differences in how people reacted to the different smiles. “Your heart doesn’t beat like a metronome,” Mr. Martin said, and “people with higher variability in their resting heart rate had more extreme cortisol responses to dominance smiles.” These new results are in line with a 2017 German study showing that people with more-variable heart rates are much better at reading others’ mental states in their facial expressions—what psychologists call mind-reading.

The current study tells us that the people with higher heart-rate variability are not only more stressed out by dominance but also more comforted by affiliative smiles. “They’re more attuned,” said Mr. Martin.

The study was on the small side, the subjects restricted to men, and each student received just one type of smile, so the experimenters couldn’t compare how a particular student would respond to different expressions.

But the study helps us to understand the arcane signals exchanged by our intensely social species. The sense of how others view us is read not just by the head but by the hormones coursing through our bodies and the rhythm of our hearts.

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Why Aren’t There More Women in Science and Technology?

A new study finds puzzling national differences: a bigger share of STEM degrees for women in Tunisia than in Sweden


By

SUSAN PINKER

March 1, 2018 10:37 a.m. ET

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A key tenet of modern feminism is that women will have achieved equity only when they fill at least 50% of the positions once filled by men. In some fields, women have already surpassed that target—now comprising, for example, 50.7% of new American medical students, up from just 9% in 1965, and 80% of veterinary students. But the needle has hardly moved in many STEM fields—such as the physical sciences, technology, engineering and math, in which barely 20% of the students are female.

A new study suggests some surprising reasons for this enduring gap. Published last month in the journal Psychological Science, the study looked at nearly a half million adolescents from 67 countries who participated in the Program for International Student Assessment, the world’s largest educational survey. Every three years, PISA gauges the skills of 15-year-olds in science, reading and math reasoning. In each testing year, the survey focuses in depth on one of those categories.

In 2015 the focus was on science literacy, which gave the psychologists Gijsbert Stoet of Leeds Beckett University and David Geary of the University of Missouri a rich data set for examining not only national differences but also the range of academic strengths and weaknesses within each student.

Some fascinating gender differences surfaced. Girls were at least as strong in science and math as boys in 60% of the PISA countries, and they were capable of college-level STEM studies nearly everywhere the researchers looked. But when they examined individual students’ strengths more closely, they found that the girls, though successful in STEM, had even higher scores in reading. The boys’ strengths were more likely to be in STEM areas. The skills of the boys, in other words, were more lopsided—a finding that confirms several previous studies.

If boys chose careers based on their own strengths—the approach usually suggested by parents and guidance counselors—they would be most likely to land in a STEM discipline or another field drawing on the same sorts of skills. Girls could choose more widely, based on their own strengths. And both, of course, would pursue their particular interests, as best they could.

Which leads to the study’s most thought-provoking finding. Based on how female students did in math and science in high school, the researchers predicted that at least 41% of girls would pursue a college STEM degree. This was indeed what they found, using Unesco education data—but only in countries with relatively weak legal protections for women, such as Algeria, Tunisia, Albania and the United Arab Emirates. So the nations with the least gender equality, as determined by the World Economic Forum’s Global Gender Gap Report, had the highest representation of women in STEM.

Conversely, nations with the strongest protections for women and the most dependable social safety nets—such as Sweden, Switzerland, Norway and Finland—had the fewest female STEM graduates, about 20% overall. The study puts the American STEM graduation rate at 24%.

I asked Wendy Williams, founder and director of the Cornell Institute for Women in Science, what she makes of these findings. She wrote that if girls expect they can “live a good life” while working in the arts, health or sciences, then girls choose to pursue what they are best at—which could be STEM, or it could be law or psychology. She added, “However, if the environment offers limited options, and the best ones are in STEM, girls focus there…Stoet’s and Geary’s findings deservedly complicate the simplistic narrative that sex differences in STEM careers are the result of societal gender biases.”

That conclusion should prompt a rethink. If women are most likely to choose STEM careers in societies that offer less equality and fewer personal freedoms, then that’s a steep price to pay just to say we’re 50/50.

in WSJ Column