NIMH Awards $9 Million Grant to Caltech Researchers

PASADENA, Calif.—The National Institute of Mental Health has awarded a five-year, $9 million grant to a research group at the California Institute of Technology (Caltech) to study the neurobiology of social decision making.

The grant establishes a Silvio O. Conte Center for Neuroscience Research at Caltech, where researchers will use electrophysiology and functional magnetic resonance imaging to investigate how humans make social decisions. The grant will support the operation of research equipment, the hiring of students and postdoctoral scholars, and the formation of a new collaborative research group.

Social decision making, in contrast to individual decision making, revolves around situations where subjects are exposed to concepts such as altruism, cooperation, punishment, and retribution. It involves learning how to make decisions by watching other people, making decisions that benefit other people, and cooperating with others to achieve a common goal. Caltech researchers will investigate how social decision making occurs at the most fundamental level in the human brain.

Ralph Adolphs, Bren Professor of Psychology and Neuroscience, will direct the center. Principal investigators will be Richard Andersen, the James G. Boswell Professor of Neuroscience; John O'Doherty, professor of psychology; and Antonio Rangel, professor of economics and neuroscience.

"This award acknowledges that basic research is of critical importance to understanding psychiatric illnesses," says Adolphs. "A large number of decisions in everyday life occur in a social context, and this breaks down in diseases ranging from autism to schizophrenia to mood disorders."

Researchers in the new center will rely on two core Caltech resources for their investigations: the Psychological Assessment Lab, led by senior research scientist Lynn Paul, for recruiting and assessing human subjects, and the Caltech Brain Imaging Center, headed by Mike Tyszka, who is a member of the professional staff.

According to Adolphs, the team has already begun planning studies to investigate the neural circuits underlying simple choices, how we learn to make good choices from other people, and how we make decisions that benefit others. 

The principal investigators are collaborating closely with several other faculty at Caltech, including Doris Tsao (assistant professor of biology), Colin Camerer (Robert Kirby Professor of Behavioral Economics), Peter Bossaerts (William D. Hacker Professor of Economics and Management and professor of finance), and Shinsuke Shimojo (Gertrude Baltimore Professor of Experimental Psychology). The Caltech group also will collaborate with investigators nationally and internationally.

Named in memory of Massachusetts Rep. Silvio O. Conte, the NIMH's Conte Centers bring together diverse expertise and cutting-edge technology to gain new knowledge about mental-health disorders with the goal of improving diagnosis and treatment.

More information is available at the Conte Center's website: conte.caltech.edu.

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Brian Bell
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Thinking and Choosing in the Brain

Caltech researchers study over 300 lesion patients

PASADENA, Calif.—The frontal lobes are the largest part of the human brain, and thought to be the part that expanded most during human evolution. Damage to the frontal lobes—which are located just behind and above the eyes—can result in profound impairments in higher-level reasoning and decision making. To find out more about what different parts of the frontal lobes do, neuroscientists at the California Institute of Technology (Caltech) recently teamed up with researchers at the world's largest registry of brain-lesion patients. By mapping the brain lesions of these patients, the team was able to show that reasoning and behavioral control are dependent on different regions of the frontal lobe than the areas called upon when making a decision.

Their findings are described online this week in the early edition of the Proceedings of the National Academy of Sciences (PNAS).

The team analyzed data that had been acquired over a 30-plus-year time span by scientists from the University of Iowa's department of neurology—which has the world's largest lesion patient registry. They used that data to map brain activity in nearly 350 people with damage, or lesions, in their frontal lobes. The records included data on the performances of each patient while doing certain cognitive tasks.

By examining these detailed files, the researchers were able to see exactly which parts of the frontal lobes are critical for tasks like behavioral control and decision making.  The intuitive difference between these two types of processing is something we encounter in our lives all the time. Behavioral control happens when you don't order an unhealthy chocolate sundae you desire and go running instead. Decision making based on reward, on the other hand, is more like trying to win the most money in Vegas—or indeed choosing the chocolate sundae.

"These are really unique data that could not have been obtained anywhere else in the world," explains Jan Glascher, lead author of the study and a visiting associate in psychology at Caltech. "To address the question that we were interested in, we needed both a large number of patients with very well-measured lesions in the brain, and also a very thorough assessment of their reasoning and decision-making abilities across a battery of tasks."

That quantification of the lesions as well as the different task measurements came from several decades of work led by two coauthors on the study: Hanna Damasio, Dana Dornsife Chair in Neuroscience at the University of Southern California (USC); and Daniel Tranel, professor or neurology and psychology at the University of Iowa.

"The patterns of lesions that impair specific tasks showed a very clear separation between those regions of the frontal lobes necessary for controlling behavior, and those necessary for how we give value to choices and how we make decisions," says Tranel.

Ralph Adolphs, Bren Professor of Psychology and Neuroscience at Caltech and a coauthor of the study, says that aspects of what the team found had been observed previously using fMRI methods in healthy people. But, he adds, those previous studies only showed which parts of the brain are activated when people think or choose, but not which are the most critical areas, and which are less important. 

"Only lesion mapping, like we did in the present study, can show you which parts of the brain are actually necessary for a particular task," he says. "This information is crucial, not only for basic cognitive neuroscience, but also for linking these findings to clinical relevance." 

For example, several different parts of the brain might be activated when you are making a particular type of decision, explains Adolphs. If there is a lesion in one of these areas, the rest of your brain might be able to compensate, leaving little or no impairment. But if a lesion occurs in another area, you might wind up with a lifelong disability in decision making. Knowing which lesion leads to which outcome is something only this kind of detailed lesion study can provide, he says.

"That knowledge will be tremendously useful for prognosis after brain injury," says Adolphs. "Many people suffer injury to their frontal lobes—for instance, after a head injury during an automobile accident—but the precise pattern of the damage will determine their eventual impairment."

According to Tranel, the team is already working on their next project, which will use lesion mapping to look at how damage to particular brain regions can impact mood and personality. " There are so many other aspects of human behavior, cognition, and emotion to investigate here, that we've barely begun to scratch the surface," he says.

Other collaborators on the PNAS paper, "Lesion Mapping of Cognitive Control and Value-based Decision-making in the Prefrontal Cortex," were Lynn Paul, a senior research scientist at Caltech; David Rudrauf and Matt Calamia from the University of Iowa; and Antoine Bechara from USC. The study was supported by grants from the German Ministry of Research and Education, the National Institutes of Health, the Kiwanis Foundation, and the Gordon and Betty Moore Foundation.

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Katie Neith
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Forging Ahead

Recently graduated Caltech senior rekindles childhood passions

It's called Greek fire. Invented around AD 670, it was one of the first flamethrowers, involving a pressurized siphon to shoot a stream of liquid flame at enemies. The Byzantine Empire used this incendiary weapon to defend against fleets of Arab ships in the first and second sieges of Constantinople in 674–678 and 717–718. "It was a very fearsome naval weapon at the time," says Tom Harris, who was one of the 232 students awarded bachelor's degrees from Caltech last week.

But historical details of the weapon—how it was invented and how it worked—are murky. That mystery made Greek fire a perfect thesis topic for Harris, who graduated with a double major in history and mechanical engineering. Working with Warren Brown, a professor of history at Caltech, Harris spent much of his senior year studying Greek fire and analyzing how it worked based on original historical documents and our modern-day understanding of fluid mechanics. He also consulted with Joe Shepherd, the C. L. Kelly Johnson Professor of Aeronautics and professor of mechanical engineering, and Tim Colonius, a professor of mechanical engineering.

His conclusions? "Greek fire was an impressive weapon, but it wasn't that effective in the naval warfare that was practiced at the time," Harris says. Although he points out that his analysis is far from definitive, he made some calculations using a simple model of how Greek fire might have worked, and found that the weapon could shoot fire as far as about 50 meters—which is not enough distance to devastate a foe in a naval battle. "A lot of people in the past have hypothesized that this device did not have a very long range, and that's why it wasn't really effective," Harris explains. "My analysis seems to corroborate that."

Harris came to Caltech with an undeclared major, thinking he would study computer science. But, having been an avid Lego builder as a kid, he was drawn to mechanical engineering. He also has an interest in medieval history, which similarly dates back to his childhood—he loved pirates and knights, and both his parents were history majors—and after he took Brown's medieval history class, his impression of the study of history changed. Instead of reading textbooks and analysis from other historians, Harris and his dozen or so classmates read and analyzed original documents.

A sampling of Harris's pieces.
Credit: Tom Harris

After his sophomore year, Harris spent a month in Rome learning about structural engineering as part of a UC Davis program. He took advantage of his time in Europe by pursuing yet another childhood passion: swords. After the program ended, he stayed in Italy for another week, taking blacksmithing lessons in Le Marche, and he then went to England for another week of lessons. He made various pieces, including metal leaves, a fire poker, and scrollwork similar to the old metal handrails you can see around Caltech's campus. In England, he forged a short sword called a seax.

The following spring break, Harris once again traveled to England, to learn swordmaking. During his free time, he spent hours at the British Museum looking at swords and other medieval weaponry.

Returning to campus, Harris discovered that other Techers were interested in blacksmithing, and so—with the help of the George W. Housner Student Discovery Fund—he led an effort to get a blacksmithing forge for the student shop on campus. The forge hasn't arrived yet, but when it does, Ben Abbott, an electrical engineer with the LIGO project and a blacksmith with more than two decades' worth of experience, has volunteered to teach students the art and craft of blacksmithing.

For Harris, blacksmithing—and Caltech—allowed him to rekindle many of his childhood passions. "You could say this experience was about rediscovering my inner child and finding a more mature way of exploring these interests," he says.

Now that he's graduated, Harris will work as a quality engineer at Covidien, a company that specializes in biomedical devices, such as stents used to unblock arteries. Although he has no experience in biomedicine, he's looking forward to learning new things—something he's gotten used to at Caltech.

"Caltech has been a place where I could feed my desire to learn," Harris says. "I'm glad for the experience I've had here."

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Marcus Woo
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L.A. Times Shines Spotlight on HSS

Caltech's core curriculum is designed to prepare students for the interdisciplinary nature of contemporary research in science and technology. As might be expected, it requires that students become well versed in mathematics and the sciences. What might come as a surprise to some is that Caltech's underclassmen are also required to complete what amounts to a class each quarter in the Division of the Humanities and Social Sciences (HSS)—and have been since the 1920s.

Last week, the Los Angeles Times turned the spotlight on this aspect of the Caltech experience, featuring several of the division's students, including Christina Kondos—the only member of this year's graduating class who majored in the humanities or social sciences without double-majoring in science, math, or engineering.

HSS division chair Jonathan Katz told the L.A. Times about the role the humanities and social sciences play in developing well-rounded scientists and engineers. "The goal is to produce science and engineering leaders," he said. "How can you lead if you can't communicate and don't understand the world? Students have to know how to write, how to communicate and be able to deal with the bigger populations."

The complete L.A. Times article, "Humanities have a place, even at Caltech," can be read online. 

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Kimm Fesenmaier
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The Path Less Traveled

Senior uses Caltech as the stepping-stone for a global education

Growing up, Katie Brennan didn't have a lot of opportunities to travel. So when she started her biology studies at Caltech, one of her main goals was to explore the world. Thanks to a plenitude of funding from the Institute, Brennan—a graduating senior—can now cross two more continents and the mountains of Washington State off her list.

Starting out small the summer after her freshman year, Brennan traveled to Detroit's Wayne State University, near her hometown of Grosse Pointe, for a SURF project. There, she did research in bioinformatics to help develop tools for analyzing the structure of RNA. Before returning to sunny SoCal, she attended a weeklong retreat, deep in the woods of Washington State, as a recipient of the annual Don Shepard Essay Contest, which awards funding for "a program of self-enrichment outside of science."

"I had a friend who took sky diving lessons, and another one built his own guitar. I went to a retreat center in the mountains," says Brennan, who had to take two planes, a bus, a ferry, and another bus to reach the old mining town of Holden, where the center was located. "I went hiking. I learned how to do pottery. There were deer eating outside of my door. It was really great."

For the summer between her sophomore and junior years, she applied for and won the Caltech Y's Studenski Award, which provides funding for students to travel and explore an area outside of academics. Brennan chose to go to Malawi to volunteer with Project Peanut Butter (PPB), a nonprofit organization focused on pediatric-malnutrition clinic work and research.

"Their aim is to end malnutrition, and they have developed a special kind of peanut butter that can help children recover from malnutrition very quickly," says Brennan, who spent a month and a half working in the clinic. "And once they've recovered, they are less likely to relapse into malnutrition. It's very impressive what the organization does."

In fact, Brennan was so impressed that she returned to Malawi this past summer to work on a PPB research project. This time, she was funded by the George W. Housner Student Discovery Fund, which provides support for independent study, including travel. 

Back in Africa, she worked on a study that looked at a correlation between environmental enteropathy—or intestinal infections linked to environmental factors—and malnutrition, spending three months in the impoverished nation of Malawi. It is not uncommon for families there with multiple children to have some kids who are malnourished and others that are not, so the study enrolled sets of young twins to compare individuals with similar genetic backgrounds and living environments. "It was fun because I got to work with hundreds of twins, and they were all so adorable," says Brennan.

Determined not to let her senior year go by without more travel, Brennan studied abroad at University College London for her first term. There, she had the ability to break away from biology courses and take a class in archaeology called Ancient Egypt in London.

"Our classes were taught in the British Museum, and we would have lectures in the Egyptian Gallery, which was a hugely unique experience," says Brennan, who also visited Paris, Oxford, and Dublin during her semester in Europe. "One of the biggest Egypt artifact museums in the world—the Petrie Museum—is actually on the UCL campus, so we also had class there, which was really great."

When she's not taking part in global excursions, Brennan is very active in both house activities and campus life—she is a member of both Blacker and Dabney houses, and was co-class president of the senior class this year. For the past three years, she has also been involved with a local charity called Elizabeth House that provides shelter for homeless pregnant women. What started as a volunteer commitment led to a part-time job and a possible career path: Brennan is hoping to work in development after graduation to fundraise for nonprofits. 

Her parting advice for new students is to apply for all the funds that Caltech has available. "There are so many!" she says. "They have funding for parties, for house life, for travel, for international research, all which really help you make the most of your experience here and away from campus."

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Katie Neith
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Hands-On Research

Caltech Neuroscientists Show How Brain Responds to Sensual Caress

PASADENA, Calif.—A nuzzle of the neck, a stroke of the wrist, a brush of the knee—these caresses often signal a loving touch, but can also feel highly aversive, depending on who is delivering the touch, and to whom. Interested in how the brain makes connections between touch and emotion, neuroscientists at the California Institute of Technology (Caltech) have discovered that the association begins in the brain's primary somatosensory cortex, a region that, until now, was thought only to respond to basic touch, not to its emotional quality.

The new finding is described in this week's issue of the Proceedings of the National Academy of Sciences (PNAS).

The team measured brain activation while self-identified heterosexual male subjects lay in a functional MRI scanner and were each caressed on the leg under two different conditions. In the first condition, they saw a video of an attractive female bending down to caress them; in the second, they saw a video of a masculine man doing the same thing. The men reported the experience as pleasurable when they thought the touch came from the woman, and aversive when they thought it came from the man. And their brains backed them up: this difference in experience was reflected in the activity measured in each man's primary somatosensory cortex.

"We demonstrated for the first time that the primary somatosensory cortex—the brain region encoding basic touch properties such as how rough or smooth an object is—also is sensitive to the social meaning of a touch," explains Michael Spezio, a visiting associate at Caltech who is also an assistant professor of psychology at Scripps College in Claremont, California. "It was generally thought that there are separate brain pathways for how we process the physical aspects of touch on the skin and for how we interpret that touch emotionally—that is, whether we feel it as pleasant, unpleasant, desired, or repulsive. Our study shows that, to the contrary, emotion is involved at the primary stages of social touch."

Unbeknownst to the subjects, the actual touches on their leg were always exactly the same—and always from a woman. Yet, it felt different to them when they believed a man versus a woman was doing the touching.

"The primary somatosensory cortex responded more to the 'female' touch than to the 'male' touch condition, even while subjects were only viewing a video showing a person approach their leg," says Ralph Adolphs, Bren Professor of Psychology and Neuroscience at Caltech and director of the Caltech Brain Imaging Center, where the research was done. "We see responses in a part of the brain thought to process only basic touch that were elicited entirely by the emotional significance of social touch prior to the touch itself, simply in anticipation of the caress that our participants would receive."

The study was carried out in collaboration with the husband-and-wife team of Valeria Gazzola and Christian Keysers, who were visiting Caltech from the University of Groningen in the Netherlands. 

"Intuitively, we all believe that when we are touched by someone, we first objectively perceive the physical properties of the touch—its speed, its gentleness, the roughness of the skin," says Gazzola. "Only thereafter, in a separable second step based on who touched us, do we believe we value this touch more or less."

The experiment showed that this two-step vision is incorrect, at least in terms of separation between brain regions, she says, and who we believe is touching us distorts even the supposedly objective representation of what the touch was like on the skin.

"Nothing in our brain is truly objective," adds Keysers. "Our perception is deeply and pervasively shaped by how we feel about the things we perceive." 

One possible practical implication of the work is to help reshape social responses to touch in people with autism.

"Now that we have clear evidence that primary somatosensory cortex encodes emotional significance of touch, it may be possible to work with early sensory pathways to help children with autism respond more positively to the gentle touch of their parents and siblings," says Spezio.

The work also suggests that it may be possible to use film clips or virtual reality to reestablish positive responses to gentle touch in victims of sexual and physical abuse, and torture.

Next, the researchers hope to test whether the effect is as robust in women as in men, and in both sexes across sexual orientation. They also plan to explore how these sensory pathways might develop in infants or children.

Two other collaborators who contributed to the PNAS paper, "Primary somatosensory cortex discriminates affective significance in social touch," are Fulvia Castelli from University College London and Joset Etzel from the University of Groningen. Funding for the study included grants from the Gordon and Betty Moore Foundation, the Dutch Science Foundation, a Scripps College Faculty Research grant, and a Marie Curie Excellence Grant.

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Katie Neith
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Caltech Research Shows Medicare Auction Will Face Severe Difficulties

Medicare's new method for buying medical supplies and equipment—everything from wheelchairs and hospital beds to insulin shots and oxygen tanks—is doomed to face severe difficulties, according to a new study by Caltech researchers.

The Center for Medicare and Medicaid Services (CMS) implemented the purchasing process—a novel type of auction—in nine metropolitan areas across the country last year and plans to expand it to 91 in 2013.

The competitive bidding process was designed to improve the efficiency of Medicare's procurement system, potentially saving taxpayers hundreds of millions of dollars. But many experts have criticized the auction, pointing out fundamental flaws in its design. Now, a series of experiments testing the auction structure show that it does, in fact, fall short of expectations. The results of the study, which was conducted by Caltech seniors Brian Merlob and Yuanjun Zhang, and Charles Plott, the Harkness Professor of Political Science and Economics, were published in the May issue of the Quarterly Journal of Economics.

In principle, auctions are a cheap and efficient way to procure goods and reward companies that can inexpensively produce their goods. In the case of the Medicare auction, various companies make bids to the government that represent their best prices for medical supplies and equipment; the government, in turn, wants the best deal and so chooses the lowest bids. For example, if 1,000 hospital beds are needed and it would take five companies to supply them all, the five lowest bids are chosen.

Unlike standard auctions, however, the CMS auction was designed with two unorthodox rules. First, the eventual selling price is set at the median of all of the winning bids. Second, bids are nonbinding, so companies can change their mind once the prices are set.

Critics say that these rules cultivate a harmful bidding strategy. To ensure a winning bid, each company will make a very low offer; this carries no risk, because the companies can cancel their bid if the median price turns out to be too low. The result is that participants in the auction will tend to make low-ball bids, assuring that the median price will also be very low—so low, in fact, that few of the companies can actually afford it, leading them to cancel their offers. At the extreme, nothing is bought or sold and, Plott says, "the auction crashes. It's just not an effective auction."

And what will happen then, critics warn, is that the government will end up negotiating prices with individual companies—negating the whole point of a competitive-bidding scheme in the first place. "You can see immediately from theoretical arguments that the potential for disaster is built right in the strategic structures," Plott says.

To determine if such theoretical predictions translate into real-world behavior, it is essential to examine experimentally how people behave in an actual auction, says Plott—who, for the last 30 years at Caltech, has been developing experimental techniques to test economic theories. He posed the problem to his experimental economics (EC 160) class. Two of his students, Merlob and Zhang, took up the challenge and spent a year researching, designing, and conducting experiments to test that behavior.

The team used computers at Caltech and the University of Maryland to run a simplified version of the CMS auction and several other auction types; one, for example, followed more standard rules, with binding bids and prices set at the lowest bid that did not win, instead of the median of all winning offers. Each auction involved 12 or 16 bidders (student volunteers from Caltech and the University of Maryland), who first had to pass a quiz showing that they understood how the auctions worked. The volunteers were given just one item to sell—a generic "thing" (since the bidders' behavior should be the same in a given auction type, regardless of the item being sold)—each at a different cost to them.

The Caltech team also examined the effect of other auction features, such as whether the costs of each item for each bidder are public knowledge and the effect of charging bidders to participate.

The results, the researchers say, convincingly support critics of the CMS auction design. "It's pretty disastrous what the bidders ended up doing," Zhang says. In the simulated CMS-type auction, some people bid $0, and the "government" was not able to buy all the items it needed. The experiments also showed that a standard auction is much more efficient and successful: the government was able to buy all the items it needed, and the bidders who had the lowest costs were the winners.

Using this experimental approach, the researchers were able to pinpoint the fundamental problem of the CMS auction design: the two rules. "If you just get rid of one of those two rules, it doesn't help—you still have problems," Plott explains. "So you have to get rid of both of them."

Last summer, 244 economists and auction experts, including Plott and Caltech professors John Ledyard, Thomas Palfrey, and Matthew Shum, signed a letter to urge President Obama to change the CMS auction system; the letter cited the Caltech experiments.

In April, however, a study released by the Department of Health and Human Services reported that the auction saved taxpayers $202.1 million in 2011, with no negative effects on health care. The report also estimates that the auction will save taxpayers and beneficiaries $42.8 billion over 10 years.

A preliminary analysis of the pilot program by Peter Cramton of the University of Maryland, an outspoken critic of the CMS auction and an economist who was not part of the Caltech study, found that the auction did in fact suffer from the problems predicted by theory and experiment. Because of the auction design, prices plunged to unsustainable levels, and suppliers dropped out, forcing Medicare to find new suppliers. Cramton also found that the number of submitted claims for equipment declined, which, he says, led to increased rates of visits to the emergency room and hospitalization. As a result, not only were overall costs higher, but so were health risks.

While Plott says he cannot comment on the report without knowing exactly how the study measured and collected its data, he remains confident in the experimental results and the theoretical arguments against the auction. "The theory gives a rather clear picture about the implications of the auction architecture," he says. "But only the data can tell us how these ideas actually play out in such a complex application with variables too numerous to be considered in the theory."

Regardless of whether the CMS will continue to expand the auction or will heed the critics' warnings, this type of research, Plott says, is a good example for how basic, scientific experiments can have direct impact on society. He considers that an especially important lesson for his students. Over the years, he says, several of his undergraduates have stuck with a project long enough to publish, occasionally leading to several awards and seminal papers. "Taking Professor Plott's class was fantastic," Merlob says. "He's a master experimentalist and an amazing mentor."

Zhang, who is doing an independent study in decision-making and neuroscience, will start graduate school in economics at UCLA in the fall; Merlob, a political science major, is still exploring his options. "This entire experience was pretty awesome," he says. "It's probably one of the best of my Caltech career."

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Marcus Woo
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Why Do People Choke When the Stakes Are High?

Caltech researchers find that loss aversion may be the culprit

PASADENA, Calif.—In sports, on a game show, or just on the job, what causes people to choke when the stakes are high? A new study by researchers at the California Institute of Technology (Caltech) suggests that when there are high financial incentives to succeed, people can become so afraid of losing their potentially lucrative reward that their performance suffers.

It is a somewhat unexpected conclusion. After all, you would think that the more people are paid, the harder they will work, and the better they will do their jobs—until they reach the limits of their skills. That notion tends to hold true when the stakes are low, says Vikram Chib, a postdoctoral scholar at Caltech and lead author on a paper published in the May 10 issue of the journal Neuron. Previous research, however, has shown that if you pay people too much, their performance actually declines.

Some experts have attributed this decline to too much motivation: they think that, faced with the prospect of earning an extra chunk of cash, you might get so excited that you will fail to do the task properly. But now, after looking at brain-scan data of volunteers performing a specific motor task, the Caltech team says that what actually happens is that you become worried about losing your potential prize. The researchers also found that the more someone is afraid of loss, the worse they perform.

In the study, each participant was asked to control a virtual object on a screen by moving an index finger that had a tracking device attached to it. The virtual object consisted of two weighted balls connected by a spring. The task was to place the object, which stretched and contracted as a weighted spring would in real life, into a square target within two seconds.

The researchers controlled for individual skill levels by customizing the size of the target so that everyone would have the same success rate. That way, people who happened to be really good or bad at this task would not skew the data.

After a training period, the subjects were asked to perform the task while inside an fMRI machine, which measures blood flow in the brain—a proxy for brain activity, since wherever a brain is active, it needs extra oxygen, and thus a larger volume of blood. By monitoring blood flow, the researchers can pinpoint areas of the brain that turn on when a particular task is performed.

The task began with the researchers offering the participants a randomized range of rewards—from $0 to $100—if they could successfully place the object into the square within the time limit. At the end of hundreds of trials—each with varying reward amounts—the participant was given their reward, based on the result of just one of the trials, picked at random.

As expected, the team found that performance improved as the incentives increased—but only when the cash reward amounts were at the low end of the spectrum. Once the rewards passed a certain threshold, which depended on the individual, performance began to fall off.

Incentives are known to activate a part of your brain called the ventral striatum, Chib says; the researchers thus expected to see the ventral striatum become increasingly active as they bumped up the prizes. And if the conventional thought were correct—that the reason for the observed performance decline was over-motivation—they would expect the striatum to continue showing a lot of activation when the incentives became high enough for performance to suffer.

What they found, instead, was that when the participants were shown their potential rewards, activity in the striatum did indeed increase with rising incentives. But once the volunteers started doing the task, striatal activity decreased with rising incentives. They also noticed that the less activity they saw in a participant's striatum, the worse that person performed on the task.

Other studies have shown that decreasing striatal activity is related to fear or aversion to loss, Chib says. "When people see the incentive that they're being offered, they initially encode it as a gain," he explains. "But when they're actually doing the task, the thing that causes them to perform poorly is that they worry about losing a potential incentive they haven't even received yet." He adds, "We're showing loss aversion even though there are no explicit losses anywhere in the task—that's very strange and something you really wouldn't expect."

To further test their hypothesis, Chib and his colleagues decided to measure how loss-averse each participant was. They had the participants play a coin-flip game in which there was an equal chance they could win or lose varying amounts of money.

Each participant was offered varying potential win-loss amounts ($20-$20, $20-$10, $20-$5, for example), and then given the opportunity to either accept each possible gamble or decline it. The win-loss ratio at which the subjects chose to take the gamble provided a measure of how loss-averse each person was; someone willing to gamble even when they might win or lose $20 is less loss-averse than someone who is only willing to gamble if they can win $20 but only lose $5.

Once the numbers had been crunched and compared to the original experiment, it turned out that the more averse a participant was, the worse they did on the task when the stakes were high. And for a particularly loss-aversive person, the threshold at which their performance started to decline did not have to be very high. "If you're more loss-averse, it really hurts you," Chib says. "You're going to reach peak performance at a lower incentive level, and your performance is also going to be worse for higher incentives."

"Previously, it's been shown that the ventral striatum is involved in mediating performance increases in response to rising incentives," says John O'Doherty, professor of psychology and coauthor of the paper. "But our study shows that changes in activity in this same region can, under certain situations, also lead to worsening performance."

While this study only involved a specific motor task and financial incentives, these results may well be universal, says Shinsuke Shimojo, the Gertrude Baltimore Professor of Experimental Psychology and another coauthor of the study. "The implications and applications can include any sort of decision making that contains high stakes and uncertainties, such as business and politics."

These findings, the researchers say, might be used to develop new ways to motivate people to perform better or to train them to be less loss-averse. "This loss aversion can be an important way of deciding how to set up incentive mechanisms and how to figure out who's going to perform well and who isn't," Chib says. "If you can train somebody to be less loss-averse, maybe you can help them avoid performing poorly in stressful situations."

The other author on the Neuron paper, "Neural mechanisms underlying paradoxical performance for monetary incentives are driven by loss aversion," is former Caltech postdoc Benedetto De Martino, who is now at the University College of London. Funding was provided by the National Science Foundation, the Gordon and Betty Moore Foundation, the Japanese Science and Technology Agency's Exploratory Research for Advanced Technology program, and the Caltech/Tamagawa University Global Center of Excellence program.

Written by Marcus Woo

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Notes from the Back Row: "What Parents Want—Evidence from Child Adoption"

What do parents want—aside from kids who come home on time and never talk with their mouths full—and why is an economist trying to answer that question? Because, at its heart, economics is all about the process of making choices. And while places like the New York Stock Exchange centralize the process of matching offers to sell with bids to buy, decentralized matching processes—finding the right job, a dream house, and even true love—play much bigger roles in our lives. Studying these processes is no mean feat, however. Data on people's collective behavior—median home prices by state, city, or even zip code, for example—is often pretty easy to come by, but the specific bits of data that led up to any individual decision—the purchase of that blue ranch house on this corner for this particular price—generally are not.

Caltech professor of economics Leeat Yariv and her colleagues found a decentralized matching process in which all the information available to each participant was recorded every step of the way, along with every decision that each participant made. The data, generated from a web-based adoption facilitator that acts as a go-between for prospective parents and birth mothers, included not only the genders, ethnicities, and marital status of all the adults involved, but the gender, ethnicity, and time to birth of the infants. In her Watson Lecture on February 15, 2012, Yariv shares her conclusions about what parents really want—as deduced from their individual choices—and discusses how policies that bar same-sex couples or single parents from adopting affect the matching process.

"What Parents Want—Evidence from Child Adoption" is available for download in HD from Caltech on iTunes U. (Episode 8)

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Doug Smith
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Inside the Brains of Jurors

Caltech Neuroscientist Helps Reveal Brain Activity Associated with Mitigating Criminal Sentences

When jurors sentencing convicted criminals are instructed to weigh not only facts but also tricky emotional factors, they rely on parts of the brain associated with sympathy and making moral judgments, according to a new paper by a team of neuroscientists. Using brain-imaging techniques, the researchers, including Caltech's Colin Camerer, found that the most lenient jurors show heightened levels of activity in the insula, a brain region associated with discomfort and pain and with imagining the pain that others feel.

The findings provide insight into the role that emotion plays in jurors' decision-making processes, indicating a close relationship between sympathy and mitigation.

In the study, the researchers, led by Makiko Yamada of National Institute of Radiological Sciences in Japan, considered cases where juries were given the option to lessen the sentences for convicted murderers. In such cases with "mitigating circumstances," jurors are instructed to consider factors, sometimes including emotional elements, that might cause them to have sympathy for the criminal and, therefore, shorten the sentence. An example would be a case in which a man killed his wife to spare her from a more painful death, say, from a terminal illness. 

"Finding out if jurors are weighing sympathy reasonably is difficult to do, objectively," says Colin Camerer, the Robert Kirby Professor of Behavioral Finance and Economics at Caltech. "Instead of asking the jurors, we asked their brains."

The researchers scanned the brains of citizens (potential jurors) while the participants read scenarios adapted from actual murder cases with mitigating circumstances. In some cases, the circumstances were sympathy-inducing; in others, where, for example, a man became enraged when an ex-girlfriend refused him, they were not. The scientists used functional magnetic resonance imaging (fMRI), a type of brain scanning that tracks increases in oxygenated blood flow, indicating heightened brain activity. The participants also had their brains scanned when they determined whether to lessen the sentences, and by how much.  

The team found that sympathy activated the dorsomedial prefrontal cortex, precuneus, and temporo-parietal junction—brain regions associated with moral conflict and thinking about the feelings of others. Similarly, the jurors had increased activity in these regions during sentencing when the mitigating circumstances earned their sympathy. In those cases, they also delivered shorter hypothetical sentences.

In addition to Camerer and Yamada, coauthors on the new paper, "Neural circuits in the brain that are activated when mitigating criminal sentences," are Saori Fujie, Harumasa Takano, Hiroshi Ito, Tetsuya Suhara, and Hidehiko Takahashi of the National Institute of Radiological Sciences; Motoichiro Kato of the Keio University of Medicine; and Tetsuya Matsuda of Tamagawa University Brain Science Institute. Yamada is also affiliated with Tamagawa University Brain Science Institute and Kyoto University School of Medicine; she and Takahashi are additionally affiliated with the Japan Science and Technology Agency.

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Kimm Fesenmaier
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