November 20, 2009
I've got a review of Stanislas Dehaene's new book, Reading in the Brain, over at the Barnes and Noble Review:
Right now, your mind is performing an astonishing feat. Photons are bouncing off these black squiggles and lines -- the letters in this sentence -- and colliding with a thin wall of flesh at the back of your eyeball. The photons contain just enough energy to activate sensory neurons, each of which is responsible for a particular plot of visual space on the page. The end result is that, as you stare at the letters, they become more than mere marks on a page. You've begun to read.
Seeing the letters, of course, is just the start of the reading process. As the neuroscientist Stanislas Dehaene reveals in his fascinating new book, Reading in the Brain, the real wonder is what happens next. Although our eyes are focused on the letters, we quickly learn to ignore them. Instead, we perceive whole words, chunks of meaning. (The irregularities of English require such flexibility. As George Bernard Shaw once pointed out, the word "fish" could also be spelled ghoti, assuming that we used the gh from "enough," the o from "women," and the ti from "lotion.") In fact, once we become proficient at reading, the precise shape of the letters -- not to mention the arbitrariness of the spelling -- doesn't even matter, which is why we read word, WORD, and WoRd the same way.
In this clearly written summary of the field, Dehaene is primarily interested in two separate mysteries. The first mystery is how the individual human brain learns to read. What changes take place inside our head between kindergarten and second grade, when most of us start to take literacy for granted? How do we go from sounding out syllables, carefully parsing the phonetics of each word, to becoming fluent readers? And how does this incredibly complicated act become automatic, so that evn ths sntnce cn b quikly undrstd?
Dehaene begins by introducing the reader to the "letterbox area," a small bit of brain just behind the left ear. The crucial role of this cortical part was first revealed by Mr. C, a 19th-century neurological patient who, after a mild stroke, lost the ability to read. What made Mr. C's case so peculiar is that his vision was perfectly fine; he could make sense of objects and faces and even numbers. However, when he opened up a book or glanced at a newspaper, the letters on the page were utterly inscrutable, a mess of inchoate lines and curves. "He [Mr.C] thinks that he has lost his mind," his doctor dryly noted.
Subsequent studies of patients with pure alexia -- they can see everything but written language -- have located the specific contours of the letterbox area. Not surprisingly, it takes up a significant chunk of our visual cortex, as the invention of the alphabet seems to have usurped brain cells previously devoted to object recognition. (Dehaene refers to this process as "neuronal recycling.") He also speculates that, while "learning to read induces massive cognitive gains," it also comes with a hidden mental cost: because so much of our visual cortex is now devoted to literacy, we're less able to "read" the details of natural world.
But reading isn't just about seeing -- we still have to imbue those syllabic sounds with meaning. This is why, once the letterbox area deciphers the word -- this takes less than 150 milliseconds -- the information is immediately sent to other brain areas, which help us interpret the semantic content. Such a complex act requires a variety of brain areas scattered across both hemispheres, all of which must work together to make sense of a sentence. If any of these particular areas are damaged, people tend to lose specific elements of language, such as the ability to conjugate verbs or decipher metaphors.
One of the most intriguing findings of this new science of reading is that the literate brain actually has two distinct pathways for reading. One pathway is direct and efficient, and accounts for the vast majority of reading comprehension -- we see a group of letters, convert those letters into a word, and then directly grasp the word's meaning. However, there's also a second pathway, which we use whenever we encounter a rare and obscure word that isn't in our mental dictionary. As a result, we're forced to decipher the sound of the word before we can make a guess about its definition, which requires a second or two of conscious effort.
The second major mystery explored by Dehaene is how reading came to exist. It's a mystery that's only deepened by the recency of literacy: the first alphabets were invented less than 4,000 years ago, appearing near the Sinai Peninsula. (Egyptian hieroglyphic characters were used to represent a Semitic language.) This means that our brain wasn't "designed" for reading; we haven't had time to evolve a purpose-built set of circuits for letters and words. As Deheane eloquently notes, "Our cortex did not specifically evolve for writing. Rather, writing evolved to fit the cortex."
Deheane goes on to provide a wealth of evidence showing this cultural evolution in action, as written language tweaked itself until it became ubiquitous. In fact, even the shape of letters -- their odd graphic design -- has been molded by the habits and constraints of our perceptual system. For instance, the neuroscientists Marc Changizi and Shinsuke Shimojo have demonstrated that the vast majority of characters in 115 different writing systems are composed of three distinct strokes, which likely reflect the sensory limitations of cells in the retina. (As Dehaene observes, "The world over, characters appear to have evolved an almost optimal combination that can easily be grasped by a single neuron.") The moral is that our cultural forms reflect the biological form of the brain; the details of language are largely a biological accident.
Deheane ends the book with a discussion of education -- he's a supporter of phonics and ridicules the whole-language method, "which does not fit with the architecture of our visual brain." It's an interesting chapter, and it's always nice to see scientists grapple with the practical implications of their work, but the most compelling themes of the book remain rooted in basic science. As Deheane and others have demonstrated, the brain is much more than the seat of the soul -- it's also the fleshy source of our culture. By studying the wet stuff inside our head, we can begin to understand why this sentence has this structure, and why this letter, this one right here, has its shape.
Posted by Jonah Lehrer at 3:10 PM • 0 Comments • 0 TrackBacks
November 19, 2009
Saks and Barneys and the rest of those luxury retailers have discovered that nothing destroys a luxury brand like a sale:
All around Saks Fifth Avenue, merchandise is sold out. The $2,520 Marni shearling vest? Gone. The $5,295 Brioni leather bomber jacket? Only one left. The $1,995 over-the-knee Christian Louboutin boots?
The $1,995 over-the-knee Christian Louboutin boots at Saks have sold out, unless you can wear the only pair left -- a size 11. "All gone, except for this," said Nick Passerelli, a Saks employee, dangling a size 11 boot from his fingers.
After a brutal year in which the nation's luxury retailers were forced to offer their wares at stunning discounts, they are trying to get their magic back. And they may have found a way: deliberately running low on merchandise.
Saks, the chic Manhattan department store, is a prime example. Its inventory is down by double digits compared with last year. That is partly a response to lower demand, of course, but it is also a business strategy aimed at weaning consumers from deep discounts. By carrying fewer goods and selling them at full price, Saks is essentially telling customers: buy it now or live without it.
"Upscale stores want to train the customer that luxury equals exclusivity and that they cannot assume they can wait and they're able to buy it on sale," said William S. Taubman, chief operating officer of Taubman Centers, a mall developer and owner.
This is bad news for people like me, who subsist on online sales. But I think it's clearly good retail policy, if only because the allure of luxury items - the irrational desire that makes us want to spend two thousand dollars on a boot - is entirely rooted in their rarity. When you put something on sale, you suggest the opposite: the object is too abundant, which is why it requires a discount.
The reason luxury items are damaged by abundance is because they are "positional goods," since part of their appeal is that they signal your social position. A Christian Louboutin boot doesn't protect your feet better than a L.L. Bean winter boot - in fact, it's probably far less functional - but it does convey a sense of identity. The fancy shoe instantly informs strangers that you're the type of person who can afford (and appreciate) such splurges, and also knows how to find something so rare. (This is an under-appreciated perk of capitalism: it allows us express ourselves with things, defining our personality with clothes, computers and brands. I'm not defending this practice - I'm simply noting that it works, and that people the world over rely on mass-produced objects to remind themselves who they are.) Last year, I talked to Jonah Berger about the quirks of luxury retail brands, and how even seemingly subtle brands - such as Prada t-shirts without the Prada logo - are still all about exclusivity:
LEHRER: You've pointed out that expensive brands come with a subtle paradox: consumers spend lots of money on these brands (such as Prada or Armani) but these high-end products are actually less likely to contain clear brand markers. Although that $20 Tommy Hilfiger polo shirt will almost certainly contain a Hilfiger logo, that $100 Prada t-shirt won't advertise its provenance. Why, then, do consumers spend so much money on expensive brands?
BERGER: Communication. Consumers want other people to think certain things about them, and so they wear clothes that communicate particular identities. Conspicuous consumption, or spending lots of money on visible goods, is a good way to try and communicate wealth, but this signal breaks down when any wannabe can buy a certain car or handbag. What were once status symbols become just aspirational markers rather than the real thing. Consequently, insiders may engage in more inconspicuous consumption to signal only to others in the know. Such subtle signals may be almost invisible to the mainstream, and this helps maintain their cache.
LEHRER: In a 2007 paper, you note that "Manhattanites stopped wearing mesh trucker hats when the bridge-and-tunnel crowd adopted them." In other words, the urbane crowd abandoned a fad once too many of the "wrong" people adopted it. You argue that this kind of switch is because consumers choose products that communicate a "desired identity." Is this true of all product domains? Or are certain consumer items more intertwined with our identity than others? If so, why? Why are hats more reflective of our identity than, say, backpacks?
BERGER: Certain domains are definitely more symbolic of identity and this fact has a lot to do with utility and function. People buy detergent based on what cleans the best, and consequently that choice doesn't say much about who they are. Shirt choice, however, is based much less on function. Two different colored shirts do an equally good job of being shirts, so observers are more likely to attribute someone's choice to something about their identity. Similarly, things that violate functionality are more likely to be seen as identity-relevant. Wearing sunglasses indoors makes it harder to see. Wearing a scarf in the summer is unnecessary. Consequently, these behaviors are more likely to be seen as signals of identity because they have little functional value.
Posted by Jonah Lehrer at 12:59 PM • 4 Comments • 0 TrackBacks
November 17, 2009
Bill Belichick has never been the most popular coach in the NFL, but his Sunday night decision to go for it on 4th and 2 on his own 28 with two minutes remaining in the fourth quarter has even his fans crying foul. I bring up this football decision not because I'm interested in a debate - as a Pats fan, the last five minutes of that game were excruciating - but because I think it illustrates the difficulty of making rational decisions, even when the evidence supports the call.
I've blogged about the research of UC Berkeley economist David Romer before, but his basic thesis, based on an exhaustive statistical analysis of 4th down scenarios, is that NFL coaches are irrationally risk-averse. They punt the ball way too frequently and kick far too many field goals.
Belichick was an econ major, and has expressed a familiarity with Romer's research. Nicholas Beaudrot has persuasively shown how, from this econometric perspective, Belichick's bizarre decision actually makes perfect sense:
On 4th down, with 2 yards or fewer to go, New England has gained a first down on approximately 66% of its attempts with Tom Brady as quarterback. The Colts had one timeout. If the Patriots gain a first down, the game ends; they can slowly walk to burn a few seconds, then take a knee on each down to end the game. If they don't gain a first down, the Colts would still need to score a touchdown to win the game. Let's give the Colts a probability P of getting the six if the ball starts at the 28 yard line. So if the Patriots try for the first, their chance of losing is
(Probability of 4th down failure) x
(Probability of Colts scoring a TD from the 28 Yard line) = 0.33P
The average New England punt nets about 40 yards. Let's give the Colts a probability Q of scoring a TD on a driving starting at the Indianapolis 32. Then, the chance of the Patriots losing is simply Q. For Belichick's decision to make sense, we just have to believe that he gave his team a lower chance of losing. In math terms, that would mean 0.33P < Q. Doing some algebra leaves you with P < 3Q. In other words, for the Patriots to have made the right decision, we only have to believe the Colts odds of scoring a TD on a drive starting 28 yards from the end zone are less than three times the odds of the same outcome starting from 68 yards out. The win probability graph for the game suggests that, given 1st-and-10 from New England's 29, the Colts had roughly a 51% chance of winning in the actual situation. We have to believe that their chances under the punt scenario were above 17% for Belichick to have made a bad good decision. Considering the Colts' have scored touchdowns on 30% of their offensive possessions, my guess is that this was a good one.
The reason I bring up this analysis is to demonstrate that even defensible decisions can have wrenching emotional consequences. Belichick's call might have been statistically correct, but it felt horribly wrong.
And this kind of contradiction isn't just relevant for football coaches. Just consider health care: the only way we're ever going to reduce medical costs is to restrict procedures that haven't passed evidence-based efficacy tests. Maybe that means 40 year old women don't get mammograms, or that we treat prostrate cancer less aggressively, or that we stop performing spinal fusion surgeries. Although there's solid evidence to question all of these medical options, such changes provoke intense debate. Why? Because our emotions don't understand statistics. Because when we have back pain we want an MRI. Because when it's our father with prostate cancer we want the most aggressive possible treatments. And so on.
The point is that there's often an indefatigable gap between the rigors of cost-benefit analyses and the emotional hunches that drive our decisions. We say we want to follow the evidence, but then the evidence rubs against a bias like loss aversion, and so we make an exception. We'll follow the evidence next time.
So here's my cheeky proposal for lowering the cost of health care: Put Belichick in charge of Medicare. Nobody likes him anyways, and he's clearly able to follow the math even when it feels like a mistake.
PS. Razib addresses a similar issue from a slightly different angle.
Update: Here's more evidence that Belichick's decision was eminently rational, and made them 9 percent more likely to win than punting the ball.
Posted by Jonah Lehrer at 5:09 PM • 9 Comments • 0 TrackBacks
Success is intimidating. When we compete against someone who's supposed to be better than us, we start to get nervous, and then we start to worry, and then we start to make stupid mistakes. That, at least, is the lesson of a new working paper by Jennifer Brown, a professor at the Kellogg school.
Brown demonstrated this psychological flaw by analyzing data from every player in every PGA tournament from 1999 to 2006. The reason she chose golf is that Tiger Woods is an undisputed superstar, the most intimidating competitor in modern sports. (In 2007, Golf Digest noted that Woods finished with 19.62 points in the World Golf Ranking, more than twice as many as his closest rival. This meant that "he had enough points to be both No. 1 and No. 2.") Brown also notes that "golf is an excellent setting in which to examine tournament theory and superstars in rank-order events, since effort relates relatively directly to scores and performance measures are not confounded by team dynamics." In other words, every golfer golfs alone.
Despite the individualistic nature of the sport, the presence of Woods in the tournament had a powerful effect. Interestingly, Brown found that playing against Woods resulted in significantly decreased performance. When the superstar entered a tournament, every other golfer took, on average, 0.8 more strokes. This effect was even more pronounced when Woods was playing well. Based on this data, Brown calculated that the superstar effect boosted Woods' PGA earnings by nearly five million dollars.
Brown argues that this phenomenon is caused when "competitors scale back their effort in events where they believe Woods will surely win." After all, why waste energy and angst on an impossible contest?
That hypothesis is certainly possible, but I'd argue that the superstar effect has more to do with "paralysis by analysis" than with decreased motivation. I'd bet that playing with Tiger Woods makes golfers extra self-conscious, and that such self-consciousness leads to choking and decreased performance. The problem, then, isn't that golfers aren't trying hard enough when playing against Tiger - it's that they're trying too hard. I wrote about this mental challenge in the London Observer earlier this year:
Scientists have begun to uncover the causes of choking, diagnosing the particular mental differences that allow some people to succeed while others wither in the spotlight. Although it might seem like an amorphous category of failure, their work has revealed that choking is triggered by a specific mental mistake: thinking too much.
The sequence of events typically goes like this: when people get nervous about performing, they become self-conscious. They start to fixate on themselves, trying to make sure that they don't make any mistakes. This can be lethal for a performer. The bowler concentrates too much on his action and loses control of the ball. The footballer misses the penalty by a mile. In each instance, the natural fluidity of performance is lost; the grace of talent disappears.
Sian Beilock, a professor of psychology at the University of Chicago, has helped illuminate the anatomy of choking. She uses golf as her experimental paradigm. When people are learning how to putt, it can seem daunting. There are just so many things to think about. Golfers need to assess the lay of the green, calculate the line of the ball, and get a feel for the grain of the turf. Then they have to monitor their putting motion and make sure that they hit the ball with a smooth, straight stroke. For an inexperienced player, a golf putt can seem unbearably hard, like a life-sized trigonometry problem.
But the mental exertion pays off, at least at first. Beilock has shown that novices hit better putts when they consciously reflect on their actions. The more time they spend thinking about the putt, the more likely they are to hole the ball. By concentrating on their game, by paying attention to the mechanics of their stroke, they can avoid beginner's mistakes.
A little experience, however, changes everything. After golfers have learned how to putt - once they have memorised the necessary movements - analysing the stroke is a waste of time. The brain already knows what to do. It automatically computes the slope of the green, settles on the best putting angle, and decides how hard to hit the ball. Bradley Hatfield, a professor of kinesiology and psychology at the University of Maryland, has monitored the brain wave activity of expert athletes during performance. (Because the subjects have to wear a bulky plastic cap full of electrodes, Hatfield can only study golfers, archers and Olympic rifle shooters.) While the brain waves of beginners show lots of erratic spikes and haphazard rhythms - this is the neural signature of a mind that is humming with conscious thoughts - the minds of expert athletes look strangely serene. When they are performing, they exhibit a rare mental tranquility, as their brain deliberately ignores interruptions from the outside world. This is neurological evidence, Hatfield says, of "the zone", that trance-like mindset which allows experts to perform at peak levels. (As the corporate motto says, the best athletes don't think: they just do it.)
Beilock's data further demonstrate the benefits of relying on the automatic brain when playing a familiar sport. She found that when experienced golfers are forced to think about their putts, they hit significantly worse shots. All those conscious thoughts erase their years of practice. "We bring expert golfers into our lab, we tell them to pay attention to a particular part of their swing, and they just screw up," Beilock says. "When you are at a high level, your skills become somewhat automated. You don't need to pay attention to every step in what you're doing."
This is what happens when people "choke". The part of their brain that monitors their behaviour starts to interfere with actions that are normally made without thinking. Performers begin second guessing skills that they have honed through years of practice. The worst part about choking is that it tends to spiral. The failures build upon each other, so a stressful situation is made more stressful.
Posted by Jonah Lehrer at 12:42 PM • 16 Comments • 0 TrackBacks
November 16, 2009
The WSJ discovers the unreliability of wine critics, citing the fascinating statistical work of Robert Hodgson:
In his first study, each year, for four years, Mr. Hodgson served actual panels of California State Fair Wine Competition judges--some 70 judges each year--about 100 wines over a two-day period. He employed the same blind tasting process as the actual competition. In Mr. Hodgson's study, however, every wine was presented to each judge three different times, each time drawn from the same bottle.
The results astonished Mr. Hodgson. The judges' wine ratings typically varied by ±4 points on a standard ratings scale running from 80 to 100. A wine rated 91 on one tasting would often be rated an 87 or 95 on the next. Some of the judges did much worse, and only about one in 10 regularly rated the same wine within a range of ±2 points.
Mr. Hodgson also found that the judges whose ratings were most consistent in any given year landed in the middle of the pack in other years, suggesting that their consistent performance that year had simply been due to chance.
It's easy to pick on wine critics, as I certainly have in the past. Wine is a complex and intoxicating substance, and the tongue is a crude sensory muscle. While I've argued that the consistent inconsistency of oenophiles teaches us something interesting about the mind - expectations warp reality - they are merely part of a larger category of experts vastly overselling their predictive powers.
Look, for instance, at mutual fund managers. They take absurdly huge fees from our retirement savings, but the vast majority of mutual funds in any given year will underperform the S&P 500 and other passive benchmarks. (Between 1982 and 2003, there have only been three years in which more than 50 percent of mutual funds beat the market.) Even those funds that do manage to outperform the market rarely do so for long. Their models work haphazardly; their success is inconsistent.
Or look at political experts. In the early 1980s, Philip Tetlock at UC Berkeley picked two hundred and eighty-four people who made their living "commenting or offering advice on political and economic trends" and began asking them to make predictions about future events. He had a long list of pertinent questions. Would George Bush be re-elected? Would there be a peaceful end to apartheid in South Africa? Would Quebec secede from Canada? Would the dot-com bubble burst? In each case, the pundits were asked to rate the probability of several possible outcomes. Tetlock then interrogated the pundits about their thought process, so that he could better understand how they made up their minds. By the end of the study, Tetlock had quantified 82,361 different predictions.
After Tetlock tallied up the data, the predictive failures of the pundits became obvious. Although they were paid for their keen insights into world affairs, they tended to perform worse than random chance. Most of Tetlock's questions had three possible answers; the pundits, on average, selected the right answer less than 33 percent of the time. In other words, a dart-throwing chimp would have beaten the vast majority of professionals. Tetlock also found that the most famous pundits in Tetlock's study tended to be the least accurate, consistently churning out overblown and overconfident forecasts. Eminence was a handicap.
But here's the worst part: even terrible expert advice can reliably tamp down activity in brain regions (like the anterior cingulate cortex) that are supposed to monitor mistakes and errors. It's as if the brain is intimidated by credentials, bullied by bravado. The perverse result is that we fail to skeptically check the very people making mistakes with our money. I think one of the core challenges in fixing our economy is to make sure we design incentive systems to reward real expertise, and not faux-experts with no track record of success. We need to fund scientists, not mutual fund managers.
Posted by Jonah Lehrer at 9:28 AM • 8 Comments • 0 TrackBacks
November 13, 2009
Ed Yong has a typically excellent post on a new paper that looks at how manipulating dopamine levels in the brain can change our predictions of future pleasure:
Tali Sharot from University College London found that if volunteers had more dopamine in their brains as they thought about events in their future, they would imagine those events to be more gratifying. It's the first direct evidence that dopamine influences how happy we expect ourselves to be.
Sharot recruited 61 volunteers and asked them to say how happy they'd feel if they visited one of 80 holiday destinations, from Greece to Thailand. All of the recruits were given a vitamin C supplement as a placebo and 40 minutes later, they had to imagine themselves on holiday at half of the possible locations. After this bout of fanciful daydreaming, they had to take another pill but this time, half of them were given L-DOPA instead of the placebo. Again, they had to imagine themselves in various holiday spots.
The next day, Sharot brought the volunteers back. By this time, they would have broken down all the L-DOPA in their system. She asked them to choose which of two destinations they'd like to go to, from the set that they had thought about the day before. Finally, they rated each destination again.
By the end of the experiments, they perceived their imaginary holidays to be more enjoyable if they had previously thought about the locations under the influence of L-DOPA (while vitamin C, as predicted, had no effect). The implication is clear: think about the future with more dopamine in the noggin and you'll imagine that you have a better time.
As I've noted before, the popular caricature of dopamine - it's the hedonistic molecule in the brain, activated by sex, drugs and rock and roll - is slightly misleading. Dopamine neurons, it turns out, don't care about pleasure per se - they're much more interested in predicting pleasure, and then comparing our predictions to the actual event. The transactions of dopamine are largely about learning - finding a way to maximize our rewards - and not about mere decadence.
What I find so interesting about this experiment is that it neatly confirmed this theory of computational neuroscience. After all, the subjects didn't feel happier after popping a pill of L-DOPA - boosting dopamine levels didn't lead to instant gratification, like Huxley's soma. Instead, it merely altered their predictions of future happiness.
But here's the funny thing about those predictions: they tend to correlate pretty accurately with our actual experience. If you think you're going to have a good time on vacation, then you probably will, just as we tend to enjoy foods and beverages and products that we expect to enjoy. (This is the consumer version of the placebo effect.) Here's how I described similar phenomena in How We Decide:
Baba Shiv, a neuroeconomist at Stanford, supplied a group of people with Sobe Adrenaline Rush, an "energy" drink that was supposed to make them feel more alert and energetic. (The drink contained a potent brew of sugar and caffeine which, the bottle promised, would impart "superior functionality"). Some participants paid full price for the drinks, while others were offered a discount. The participants were then asked to solve a series of word puzzles. Shiv found that people who paid discounted prices consistently solved about thirty percent fewer puzzles than the people who paid full price for the drinks. The subjects were convinced that the stuff on sale was much less potent, even though all the drinks were identical. "We ran the study again and again, not sure if what we got had happened by chance or fluke," Shiv says. "But every time we ran it we got the same results."
Why did the cheaper energy drink prove less effective? According to Shiv, consumers typically suffer from a version of the placebo effect. Since we expect cheaper goods to be less effective, they generally are less effective, even if they are identical to more expensive products. This is why brand-name aspirin works better than generic aspirin, or why Coke tastes better than cheaper colas, even if most consumers can't tell the difference in blind taste tests. "We have these general beliefs about the world⎯for example, that cheaper products are of lower quality⎯and they translate into specific expectations about specific products," said Shiv. "Then, once these expectations are activated, they start to really impact our behavior.
So the next time you buy something on sale, pop a pill of L-DOPA. It will increase your pleasure, if only because you expect it to.
Posted by Jonah Lehrer at 11:20 AM • 5 Comments • 0 TrackBacks
November 10, 2009
David Dobbs has a fantastic new article on behavioral genetics at The Atlantic. He adds an important amendment to the vulnerability hypothesis, which holds that certain genes make people more vulnerable to psychiatric disorders. While these snippets of DNA aren't deterministic per se, when they are combined with traumatic childhood events, or a stressful few months, they can lead to serious mental illness. It's the old genes plus environment story, and it's typically cast in a negative light. But Dobbs finds that the vulnerability hypothesis comes with a positive (and often overlooked) flip-side:
At first glance, this idea, which I'll call the orchid hypothesis, may seem a simple amendment to the vulnerability hypothesis. It merely adds that environment and experience can steer a person up instead of down. Yet it's actually a completely new way to think about genetics and human behavior. Risk becomes possibility; vulnerability becomes plasticity and responsiveness. It's one of those simple ideas with big, spreading implications. Gene variants generally considered misfortunes (poor Jim, he got the "bad" gene) can instead now be understood as highly leveraged evolutionary bets, with both high risks and high potential rewards: gambles that help create a diversified-portfolio approach to survival, with selection favoring parents who happen to invest in both dandelions and orchids.
In this view, having both dandelion and orchid kids greatly raises a family's (and a species') chance of succeeding, over time and in any given environment. The behavioral diversity provided by these two different types of temperament also supplies precisely what a smart, strong species needs if it is to spread across and dominate a changing world. The many dandelions in a population provide an underlying stability. The less-numerous orchids, meanwhile, may falter in some environments but can excel in those that suit them. And even when they lead troubled early lives, some of the resulting heightened responses to adversity that can be problematic in everyday life--increased novelty-seeking, restlessness of attention, elevated risk-taking, or aggression--can prove advantageous in certain challenging situations: wars, tribal or modern; social strife of many kinds; and migrations to new environments. Together, the steady dandelions and the mercurial orchids offer an adaptive flexibility that neither can provide alone. Together, they open a path to otherwise unreachable individual and collective achievements.
This orchid hypothesis also answers a fundamental evolutionary question that the vulnerability hypothesis cannot. If variants of certain genes create mainly dysfunction and trouble, how have they survived natural selection? Genes so maladaptive should have been selected out. Yet about a quarter of all human beings carry the best-documented gene variant for depression, while more than a fifth carry the variant that Bakermans-Kranenburg studied, which is associated with externalizing, antisocial, and violent behaviors, as well as ADHD, anxiety, and depression. The vulnerability hypothesis can't account for this. The orchid hypothesis can.
This is a transformative, even startling view of human frailty and strength. For more than a decade, proponents of the vulnerability hypothesis have argued that certain gene variants underlie some of humankind's most grievous problems: despair, alienation, cruelties both petty and epic. The orchid hypothesis accepts that proposition. But it adds, tantalizingly, that these same troublesome genes play a critical role in our species' astounding success.
The orchid hypothesis--sometimes called the plasticity hypothesis, the sensitivity hypothesis, or the differential-susceptibility hypothesis--is too new to have been tested widely. Many researchers, even those in behavioral science, know little or nothing of the idea. A few--chiefly those with broad reservations about ever tying specific genes to specific behaviors--express concerns. But as more supporting evidence emerges, the most common reaction to the idea among researchers and clinicians is excitement. A growing number of psychologists, psychiatrists, child-development experts, geneticists, ethologists, and others are beginning to believe that, as Karlen Lyons-Ruth, a developmental psychologist at Harvard Medical School, puts it, "It's time to take this seriously."
Posted by Jonah Lehrer at 3:28 PM • 7 Comments • 0 TrackBacks
November 9, 2009
A new paper by scientists at the Weizmann Institute documents the primal connection between whiffs of smell and episodic memory. This nasal nostalgia is mediated by the hippocampus, the manufacturer of long-term memory in the brain. Here's the abstract:
Authors, poets, and scientists have been fascinated by the strength of childhood olfactory memories. Indeed, in long-term memory, the first odor-to-object association was stronger than subsequent associations of the same odor with other objects. Here we tested the hypothesis that first odor associations enjoy a privileged brain representation. Because emotion impacts memory, we further asked whether the pleasantness of an odor would influence such a representation. On day 1, we associated the same visual objects initially with one, and subsequently with a second, set of pleasant and unpleasant olfactory and auditory stimuli. One week later, we presented the same visual objects and tested odor-associative memory concurrent with functional magnetic resonance brain imaging. We found that the power (% remembered) of early associations was enhanced when they were unpleasant, regardless of whether they were olfactory or auditory. Brain imaging, however, revealed a unique hippocampal activation for early olfactory but not auditory associations, regardless of whether they were pleasant or unpleasant. Activity within the hippocampus on day 1 predicted the olfactory but not auditory associations that would be remembered one week later. These findings confirmed the hypothesis of a privileged brain representation for first olfactory associations.
As the scientists note, artists have long described the powerful linkage of smell and the past. Here's Marcel Proust, explaining the madeleine:
"When from a long distant past nothing subsists, after the people are dead, after the things are broken and scattered, taste and smell alone, more fragile but enduring, more unsubstantial, more persistent, more faithful, remain poised a long time, like souls, remembering, waiting, hoping, amid the ruins of all the rest; and bear unflinchingly, in the tiny and almost impalpable drop of their essence, the vast structure of recollection."
As I noted in Proust Was A Neuroscientist, these ornate subclauses contain some prophetic insights into how our brain works. In 1911, the year Proust began writing his novel, anatomists had no idea how our senses connected inside the skull - the brain was three pounds of mysterious mush. One of Proust's hypotheses, however, was that our senses of smell and taste bear a unique burden of memory. That's why he makes it clear that just looking at the seashell shaped cookie, which he'd glimpsed countless times in patisserie windows, brought back nothing; Combray remained lost. In fact, Proust even goes so far as to blame his sense of sight for obscuring his childhood memories in the first place. "Perhaps because I had so often seen such madelines without tasting them," Proust writes, "that their image had disassociated itself from those Combray days." Luckily for literature, Proust decided to put the cookie in his mouth. As he writes, it was "by taste and smell alone" that his childhood memories came flooding back.
Why is smell so sentimental? One possibility, which is supported by this recent experiment, is that the olfactory cortex has a direct neural link to the hippocampus. In contrast, all of our other senses (sight, touch and hearing) are first processed somewhere else - they go to the thalamus - and only then make their way to our memory center. This helps explain why we're so dependent on metaphors to describe taste and smell. We always describe foods by comparing them to something else, which we've tasted before. ("These madeleines taste just like my grandmother's madeleines!" Or: "These madeleines taste like the inside of a lemon poppy seed cake!") In contrast, we have a rich language of adjectives to describe what we see and hear, which allows us to define the sensory stimulus in lucid detail. As a result, we don't have to lean so heavily on simile and comparison.
It's also worth noting, of course, that the data doesn't quite support the strong version of the Proustian hypothesis. While olfactory associations enjoy a "privileged brain representation," that hippocampal link is less important than the unpleasantness of the smell, which is much better at predicting whether or not we'll remember the memory a few days later. This is the bleak truth of the brain: it clings to what we don't like.
For more, check out the work of Rachel Herz. And thanks to Jason Synder for the tip!
Posted by Jonah Lehrer at 11:01 AM • 10 Comments • 0 TrackBacks
November 6, 2009
This is absolutely fascinating, yet another reminder that the structure of language infects everything. Here's Nell Greenfieldboyce, at NPR:
The distinctive sounds of a newborn's first cries may be influenced by the mother tongue of its parents.
A new study of over a thousand recorded cries from 30 French newborns and 30 German newborns found differences in the cries' melody patterns. French cries tended to have a rising melody, while the German cries tended to have a falling melody.
The finding suggests that newborns just a few days old may already be trying to imitate the prevailing intonation patterns of the language they heard while still in the womb.
The moral is that, even before we're born, we are deeply influenced by the syllables and grammars that surround us. The words are still meaningless, and yet they leave a meaningful mark on the brain. This reminds me of that great Wallace Stevens quote: "Speech is not dirty silence/Clarified. It is silence made still dirtier." Babies, it turns out, are also corrupting the silence with a kind of speech. From the moment our brain is made, we start to express ourselves in the terms and forms of language, so that even the most instinctive utterance - the scream of a newborn - is still shaped by culture.
UPDATE: Important qualifications from the always lucid Language Log:
This is a really interesting and suggestive study, which needs to be replicated to be entirely convincing. It finds a fairly large difference in the distribution of pitch and amplitude profiles of French and German neonates, with the French babies tending to produce cries with later peaks that the German babies. The effect size in the reported data is a large one (d=1.0).
Posted by Jonah Lehrer at 1:14 PM • 6 Comments • 0 TrackBacks
