Captivated by Critters: Humans Are Wired to Respond to Animals

PASADENA, Calif.—Some people feel compelled to pet every furry animal they see on the street, while others jump at the mere sight of a shark or snake on the television screen. No matter what your response is to animals, it may be thanks to a specific part of your brain that is hardwired to rapidly detect creatures of the nonhuman kind. In fact, researchers from the California Institute of Technology (Caltech) and UCLA report that neurons throughout the amygdala—a center in the brain known for processing emotional reactions—respond preferentially to images of animals.

Their findings were described in a study published online in the journal Nature Neuroscience.

The collaborative research team was responsible for recruiting 41 epilepsy patients at the Ronald Reagan UCLA Medical Center; these patients were already being monitored for brain activity related to seizures. Using electrodes already in place, the team recorded single-neuron responses in the amygdala as study participants viewed images of people, animals, landmarks, or objects. The amygdalae are two almond-shaped clusters of neurons—cells that are core components of the nervous system—located deep in the medial temporal lobe of the brain.  

"Our study shows that neurons in the human amygdala respond preferentially to pictures of animals, meaning that we saw the most amount of activity in cells when the patients looked at cats or snakes versus buildings or people," says Florian Mormann, lead author on the paper and a former postdoctoral scholar in the Division of Biology at Caltech. "This preference extends to cute as well as ugly or dangerous animals and appears to be independent of the emotional contents of the pictures. Remarkably, we find this response behavior only in the right and not in the left amygdala."

Mormann says this striking hemispheric asymmetry helps strengthen previous findings supporting the idea that, early on in vertebrate evolution, the right hemisphere became specialized in dealing with unexpected and biologically relevant stimuli, or with changes in the environment. "In terms of brain evolution, the amygdala is a very old structure, and throughout our biological history, animals—which could represent either predators or prey—were a highly relevant class of stimuli," he says. 

"This is a pretty novel finding, since most amygdala research in the past was usually about faces of people and emotions related to fear rather than pictures of animals," adds Ralph Adolphs, a coauthor on the paper and Bren Professor of Psychology and Neuroscience and professor of biology at Caltech. "Nobody would have guessed that cells in the amygdala respond more to animals than they do to human faces, and in particular that they respond to all kinds of animals, not just dangerous ones. I think this will stimulate more research and has the potential to help us better understand phobias of animals."

The study is also a clear illustration of how scientists doing basic research can benefit from working with collaborators in a clinical setting and vice versa.

"This is a good example of how special situations in neurosurgery—in this case, patients who are treated in order to cure their epilepsy—can provide a unique window into the workings of the human mind," says Itzhak Fried, a UCLA neurosurgeon and a coauthor of the study.

"A category-specific response to animals in the right human amygdala" was featured online on August 28 as an advance online publication of Nature Neuroscience. The Caltech team was led by Christof Koch, Troendle Professor of Cognitive and Behavioral Biology, and included Julien Dubois, Simon Kornblith, Milica Milosavljevic, Moran Cerf, Naotsugu Tsuchiya, and Alexander Kraskov. Rodrigo Quian Quiroga and Matias Ison from the University of Leicester also contributed to the study.

The research was supported by the European Commission, the National Research Foundation of Korea, the National Institute of Neurological Disorders and Stroke, the G. Harold and Leila Y. Mathers Foundation, the Gimbel Discovery Fund, and the Dana Foundation.  

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Pondering Decisions

The sky is gray, but you're not sure if the clouds will clear or rain will pour. Do you grab an umbrella when you go outside?

Decisions like this are filled with ambiguity, and we're faced with them every day, whether picking stocks or choosing the sweetest watermelon at the store. "Almost every decision has some ambiguity," says Kota Saito, an economist who develops empirical and mathematical models on how people make decisions—gaining insight into human behavior that can inform socioeconomic policy. This fall, he joins Caltech as an assistant professor and the newest faculty member of the Division of the Humanities and Social Sciences. 

In mid-August, just a few days after he arrived in Pasadena, Saito's office in Baxter was still relatively empty, with a bare bookcase and blank walls. His whiteboard, however, was already crowded with letters, symbols, and equations that describe how people make choices. Saito's research focuses on two types of decision making: decisions that are inherently ambiguous (do you grab the umbrella?) and those that deal with inequality and fairness—for example, how you would distribute certain goods. "Suppose I only have one chocolate bar," he says. "How should I share it with you?"

Although his research is theoretical and mathematical in nature, he explains, a crucial part of his work is the use of experimental evidence to establish a set of principles about human behavior. Classical economics assumes that a given person, being "rational," will want all the goods for himself. Therefore, in the chocolate-bar scenario, he would keep the entire bar and not share. But data shows that decision making is more subtle and complex, and that people actually take into account how their decisions affect others. 

Saito takes this type of observed data and whittles it down to several simple principles. For example, one of those principles might say that a person prefers an outcome where no one receives anything rather than an outcome in which one lucky person gets everything. Then he mathematically proves that a person's choice satisfies those principles if and only if that choice is governed by a certain equation called a utility function. The utility function describes how people weigh the costs and benefits of a decision.

The ideas from his research can be used to inform policy in which inequality and fairness matter, such as the tax code—an especially hot political topic these days. But since his equations are based on controlled, idealized scenarios, Saito cautions against applying them directly to the real world. Nevertheless, he says, gleaning new insights into how people evaluate choices and how they consider the effects of those choices on others is important when forming socioeconomic policies.

Saito has been interested in psychology, political science, and sociology since he was a teenager. But he found himself drawn to the mathematical approaches in decision theory, which led him to study economics; he earned an MS from the University of Tokyo in 2007 and a PhD from Northwestern last spring. Now at Caltech, Saito hopes to show students that the experimental and mathematical methods normally used for the natural sciences can also be applied to the social sciences.

"I'm happy to be here," he says. "Caltech is the best place for microeconomic theory and experimental economics, and I'm excited to work with my new colleagues." And Southern California's weather is always a plus: "It's a really wonderful place—especially because I'm from Chicago," he says. "Here it's always sunny."

Which means he can probably leave his umbrella at home.

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Think Healthy, Eat Healthy: Caltech Scientists Show Link Between Attention, Self-Control

PASADENA, Calif.—You're trying to decide what to eat for dinner. Should it be the chicken and broccoli? The super-sized fast-food burger? Skip it entirely and just get some Rocky Road?

Making that choice, it turns out, is a complex neurological exercise. But, according to researchers from the California Institute of Technology (Caltech), it's one that can be influenced by a simple shifting of attention toward the healthy side of life. And that shift may provide strategies to help us all make healthier choices—not just in terms of the foods we eat, but in other areas, like whether or not we pick up a cigarette.

Their research is described in a paper published in the July 27 issue of the Journal of Neuroscience.

When you decide what to eat, not only does your brain need to figure out how it feels about a food's taste versus its health benefits versus its size or even its packaging, but it needs to decide the importance of each of those attributes relative to the others. And it needs to do all of this more-or-less instantaneously.

Antonio Rangel, professor of economics and neuroscience at Caltech, has been studying this value-deriving and decision-making process for years now. Along with Todd Hare—a former postdoc at Caltech who is now an assistant professor of neuroeconomics at the University of Zurich in Switzerland—he published a paper in Science in 2009 describing differences in the brains of people who are better at exercising self-control than others. What they found was that while everyone uses the same area of the brain—the ventral medial prefrontal cortex, or vmPFC—to make value-laden decisions like what to munch on, there's a second brain area—the dorsolateral prefrontal cortex, or dlPFC—that seems to come to life when a person is using self-control during the decision-making process.

In other words, when the dlPFC is active, it allows the vmPFC to take into account health benefits as well as taste when it assigns a value to a particular food.

The new study goes a step further, showing that there seem to be ways to help kickstart the dlPFC through the use of what Hare calls "external cues" that allow us to exhibit more self-control than we might have otherwise.

The researchers came to their conclusions based on data from a brain-imaging experiment conducted with 33 adult volunteers, none of whom were following a specific diet or trying to lose weight for any reason. Each of the volunteers was shown 180 different food items—from chips and candy bars to apples and broccoli—through a set of video goggles while in a functional magnetic resonance imaging (fMRI) machine.

The hungry subjects—they were asked to fast for at least three hours prior to the experiment—were given up to three seconds to respond to each picture with a decision about whether or not they'd want to eat the food shown after the experiment was over. They could either give the food a "strong no," a "no," a "yes," or a "strong yes." Once all of the images had been flipped through, a single food image was chosen at random; if the volunteer had said "yes" or "strong yes" to the idea of eating that food, he or she was served that item.

"Because only one random trial was selected to 'count,'" says Rangel, "the optimal strategy for subjects is to treat each decision as if it were the only one."

Simple, right? But here's the catch: before every 10 food choices, an instruction would come on the screen for five seconds telling the subjects either to "consider the healthiness," "consider the tastiness," or "make decisions naturally." This meant that of the 180 decisions, the subjects made 60 in each of the three "instruction conditions."

What this was meant to do, Rangel explains, is shift the subject's attention during the experiment and, potentially, shift the way in which they made decisions.

Afterward—outside the scanner—the subjects were asked to rate the same foods on both a tastiness scale (very untasty, untasty, tasty, very tasty) and a healthiness scale (very unhealthy, unhealthy, healthy, very healthy). That way, the researchers were able to associate the choices the subjects made during the brain scan with their stated perceptions of those foods' attributes—showing that a subject who chose broccoli during the "consider the healthiness" portion of the test might think of it nonetheless as untasty.

The researchers then classified the foods for each subject based on that subject's ratings: unhealthy-untasty, healthy-untasty, unhealthy-tasty, and healthy-tasty. Unsurprisingly, people chose healthy-tasty foods no matter where their attention had been directed.

Things got interesting when the researchers looked at the other three categories, however. Among their findings:

  • When thinking about healthiness, subjects were less likely to eat unhealthy foods, whether or not they deemed them to be tasty, and more likely to eat healthy-untasty foods.
  • Being asked to think about healthiness led subjects to say "no" to foods more often than they did when asked to make decisions naturally.
  • There were no real differences between the choices made during the "consider the tastiness" and "make decisions naturally" portions of the experiment.

When the researchers turned to the fMRI results, they found that the vmPFC was, as predicted, "more responsive to the healthiness of food in the presence of health cues," says Rangel. And, as they'd seen previously, the robustness of that response was due to the influence of the dlPFC—that bastion of self-control—which was much quieter when the study's subjects were thinking about taste or their own personal choice than when they were asked to throw healthiness into the equation.

"This increased influence of the health signals on the vmPFC results in an overall value for the food that is based more on its health properties than is the case when the subject's attention is not focused on healthiness," says Hare.

These results are most likely not limited just to choices about food, Hare says. "Our findings are also relevant to the current changes to cigarette warnings many governments have started to make," he notes. "These changes include adding graphical images of the health risks of smoking. It remains to be seen whether these images will be more effective in drawing attention to the unhealthiness of smoking than the text warnings. If the graphical warnings do increase attention to health, then our results suggest that they could decrease the desire to smoke."

Jonathan Malmaud, a former research assistant at Caltech who is now a graduate student at MIT, was also an author on the Journal of Neuroscience paper, "Focusing attention on the health aspects of foods changes value signals in the vmPFC and improves dietary choice." The scientists' work was funded by a grant from the National Science Foundation.

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Lori Oliwenstein
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Caltech Researchers Pinpoint Brain Region That Influences Gambling Decisions

PASADENA, Calif.—When a group of gamblers gather around a roulette table, individual players are likely to have different reasons for betting on certain numbers. Some may play a "lucky" number that has given them positive results in the past—a strategy called reinforcement learning. Others may check out the recent history of winning colors or numbers to try and decipher a pattern. Betting on the belief that a certain outcome is "due" based on past events is called the gambler's fallacy.

Recently, researchers at the California Institute of Technology (Caltech) and Ireland's Trinity College Dublin hedged their bets—and came out winners—when they proposed that a certain region of the brain drives these different types of decision-making behaviors.

"Through our study, we found a difference in activity in a region of the brain called the dorsal striatum depending on whether people were choosing according to reinforcement learning or the gambler's fallacy," says John O'Doherty, professor of psychology at Caltech and adjunct professor of psychology at Trinity College Dublin. "This finding suggests that the dorsal striatum is particularly involved in driving reinforcement-learning behaviors."

In addition, the work, described in the April 27 issue of The Journal of Neuroscience, suggests that people who choose based on the gambler's fallacy may be doing so because at the time of the choice they are not taking into account what they had previously learned or observed.

The focus of O'Doherty's research is to understand the brain mechanisms that underlie the decisions people make in the real world. To study this kind of decision making in the lab, his team gets study participants to play simple games in which they make choices that result in winning or losing small amounts of money. To make these games interesting, the researchers often present simple "gambling" scenarios, such as playing slot machines or roulette.

"For this particular study, we were interested in what part of the brain might play a role in controlling these strategies that drive behavior," says O'Doherty, who conducted the study along with postdoctoral scholar Ryan Jessup.

The team asked 31 participants to complete four roulette-wheel tasks while lying in an MRI scanner. For each round, the volunteers were asked to choose a color on a tricolored spinning wheel. If the wheel stopped on their color, they won two euros. (The study was done at Trinity College Dublin.) For each round, participants were charged a half euro, regardless of the outcome. All the while, the researchers studied the brain activity of participants, with a focus on how they appeared to choose colors.

"The dorsal striatum was more active in people who, at the time of choice, chose in accordance with reinforcement-learning principles compared to when they chose according to the gambler's fallacy," says Jessup. "This suggests that the same region involved in learning is also used at the time of choice."  

The two types of strategies are actually contradictory because in reinforcement-learning behavior, one would be more likely to choose something if it has won a lot recently, and less likely to choose something if it has lost a lot recently. The opposite is true of the gambler's fallacy.

"The task was novel because making decisions based on either reinforcement learning or the gambler's fallacy is not rational in this particular task, and yet most of the subjects acted irrationally," explains Jessup. "Only 8 out of 31 subjects were generally rational, meaning they simply chose the color that covered the largest area in that round."

"It is very important to try to understand how interactions between different brain areas result in different types of decision-making behavior," says O'Doherty. "Once we understand the basic mechanisms in healthy people, we can start to look at how these systems go wrong in patients who suffer from different diseases, such as psychiatric disorders or addiction, that impact their decision-making capabilities."

The study, "Human Dorsal Striatal Activity during Choice Discriminates Reinforcement Learning Behavior from the Gambler's Fallacy," was supported by a Science Foundation Ireland grant.

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Law Expert Wins Feynman Prize for Excellence in Teaching

J. Morgan Kousser, professor of history and social science at the California Institute of Technology (Caltech), has been awarded the Richard P. Feynman Prize for Excellence in Teaching—Caltech's most prestigious teaching honor.

Kousser was selected for his "exceptional ability to draw science and engineering students to appreciate the intellectual rigors of legal thought."

The Feynman Prize was established in 1993 "to honor annually a professor who demonstrates, in the broadest sense, unusual ability, creativity, and innovation in undergraduate and graduate classroom or laboratory teaching." Any member of the Caltech community, including faculty, students, postdoctoral scholars, alumni, and staff, may nominate a faculty member for the award, and the winner is selected by a committee appointed by the provost.

"Although people outside Caltech are sometimes shocked to find that we teach history and political science, English, economics, and philosophy, undergraduates here can get close attention from internationally known professors much more easily than at almost any other college in the U.S.," says Kousser. "Winning the Feynman Prize is a recognition of how much great teaching goes on in the humanities and social sciences division at Caltech and how central our division is to the undergraduate experience at Caltech."

A member of the Caltech faculty since 1969, Kousser is the author of The Shaping of Southern Politics: Suffrage Restriction and the Establishment of the One-Party South, 1880–1910 and Colorblind Injustice: Minority Voting Rights and the Undoing of the Second Reconstruction. His research focuses on minority voting rights, the history of education, and the legal and political aspects of race relations in the 19th and 20th centuries.

Kousser has served as an expert witness in 28 federal or state voting-rights cases and as a consultant in 10 others, and he testified before a subcommittee of the U.S. House of Representatives in 1981 about the renewal of the Voting Rights Act. He received his AB in 1965 from Princeton, and his MPhil and PhD from Yale University in 1968 and 1971, respectively. He also holds an honorary MA from Oxford University.

In nomination letters written by students, Kousser was commended for holding his students to high standards and driving them to excel as critical thinkers. Several students described him as one of the most inspiring and demanding instructors at the Institute. The award citation remarked that his passion for his subject matter has even "drawn students to change their career path to pursue law, a remarkable achievement in an environment so dominated by science and engineering."

"Under his tutelage, many Caltech students—myself included—grow from politics neophytes into judicial experts over the course of the two terms of Law 148," said Elizabeth Mak, a senior in biology, in her letter nominating Kousser for the prize. "Professor Kousser's unique teaching style hinges on the strength of the respect his students have for him. Simply put, he inspires his students."

Kousser says he enjoys teaching at Caltech because he has the opportunity to structure classes so that students cannot avoid teaching themselves. He also appreciates that Caltech students take up his challenges "with verve and brilliance."

"I get a prize every year—watching students grow not only in knowledge, but in fascination with topics they were barely aware of before," says Kousser. "The real prize is the light in their eyes."

Previous winners of the Feynman Prize have included Dennis Dougherty, George Grant Hoag Professor of Chemistry; Jehoshua (Shuki) Bruck, Gordon and Betty Moore Professor of Computation and Neural Systems and Electrical Engineering; and Zhen-Gang Wang, professor of chemical engineering.

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Katie Neith
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Caltech Receives $12.3 Million to Train Scientific Leaders in Business and Industry

The California Institute of Technology (Caltech) has announced the creation of the Ronald and Maxine Linde Institute of Economic and Management Sciences. The initiative will bring together the best scientific minds and the best quantitative business practices, permitting a distinctive and targeted educational opportunity for Caltech's students and providing cutting-edge research opportunities for Caltech's faculty.

The new institute will be funded with an $8.2 million endowment established by Ronald and Maxine Linde and a $4.1 million addition to the endowment from the Gordon and Betty Moore matching program.

"Caltech students benefit greatly from exposure to the intellectual tools to become responsible, capable entrepreneurs and business managers," says Caltech's president, Jean-Lou Chameau. "By establishing the Linde Institute of Economic and Management Sciences, Ronald and Maxine Linde will foster the future growth of education and research activities that will prepare our students to assume leadership roles in industry and academia."

The new institute will be multidisciplinary, building on the success of Caltech's current Business, Economics, and Management (BEM) program by organizing its education and research activities into a single entity. BEM is an undergraduate option launched in 2002 and administered by the Division of the Humanities and Social Sciences (HSS).

The Linde Institute will be led by Peter Bossaerts, the William D. Hacker Professor of Economics and Management and professor of finance at Caltech, and will bring together current faculty while enhancing the Institute's ability to recruit additional scholars working in these areas.

"The new institute will enable Caltech to build on the excellence of its current research in the interdisciplinary areas that impact economics and management," says Ronald Linde, vice chair of Caltech's Board of Trustees. "It also will allow Caltech to equip its students with the proper background and tools to excel should they choose to become entrepreneurs or should they become involved in technology management."

Caltech is one of the few institutions at which such a program could be attempted, Linde adds, "because it combines an exceptional student population with a faculty that has chosen to pursue only the most analytically rigorous approach to business, economics, and management education."

"Caltech has taken a unique approach to the study of business," says HSS division chair Jonathan N. Katz. "Differing from a traditional business school model that is based primarily on inductively studying cases, Caltech's BEM program is rigorous, quantitative, and highly interdisciplinary. It provides students with analytical and conceptual tools to succeed in a modern, volatile business environment. To our knowledge, Caltech is the only institution to apply this social-scientific approach to undergraduate business education."

However, he adds, the BEM program—which is currently one of the most popular majors for students at Caltech—has "reached a threshold," requiring additional support to create a stronger infrastructure and unite the faculty working both within BEM and across Caltech's scientific disciplines.

"The Linde Institute will create a forum for sharing resources and making connections across campus," says Katz. "And it will foster the future growth and development of education and research activities."

The Lindes have sponsored numerous other scientific and research-intensive activities at Caltech, as well as a research facilities challenge grant. In 2008, the Lindes established an $18 million endowment at Caltech to create the Ronald and Maxine Linde Center for Global Environmental Science, which will be housed in a renovated 1930s laboratory. The Linde + Robinson Laboratory is scheduled to open in early 2012.

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Caltech Neuroscientists Study "Fearless" Woman

Armed with tarantulas, snakes, and horror-movie clips, Caltech neuroscientists, together with collaborators at the University of Iowa and the University of Southern California (USC), have studied a woman who is unable to experience the emotion of fear.

The work, described in the December 16 online issue of the journal Current Biology, provides the first in-depth investigation of how the experience of fear depends on a specific brain region called the amygdala and offers new insight into our conscious experience of emotions. The amygdalae, which register rapid emotional reactions, are implicated in depression, anxiety, and autism.

The individual, a woman known as SM who has extensive damage to the amygdala on both sides of her brain—rendering the brain regions essentially non-functional—showed no fear when subjected to numerous situations that normally induce the emotion.

The research team measured fear behavior by videotaping the subject as she walked through a haunted house at Halloween, handled large tarantulas and snakes in an exotic pet store, and viewed frightening film clips from horror movies. Detailed questionnaires and interviews were used to explore her experience of fear in response to all these situations, and during the day-to-day events in her real life.

"The complete absence of any fear behavior, or any report of subjective fear experience, was truly remarkable," says Justin Feinstein, a graduate student in clinical psychology at the University of Iowa and first author on the study. "This was especially striking because SM can feel emotions other than fear normally. This was not a subtle impairment, but something that just hit you in the face."

The other members of the research team were Ralph Adolphs, the Bren Professor of Psychology and Neuroscience at Caltech; Antonio Damasio, Dornsife Professor of Neuroscience and Director of the Brain and Creativity Institute at USC; and Daniel Tranel, Professor of Psychology and Neurology at the University of Iowa. The investigators have a long history of collaboration using an expansive registry of brain lesion patients at the University of Iowa.

According to Adolphs, the findings are especially valuable in light of the large amount of research on the amygdala in animals showing that the brain region is important for fear behaviors and fear learning. "One thing you simply cannot measure definitively in animals is their conscious experience of fear," Adolphs argues. "This study really fills an important open question; we had all assumed that the amygdala would be important for many aspects of fear processing, but demonstrating it also plays a role in feeling fear was not trivial to do."

In addition, Tranel says, "these findings will be of special importance to understanding psychiatric illnesses in which the amygdala is thought to be dysfunctional, such as depression, PTSD, and phobias."

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Alvarez on Alaska

Alaska's controversial and still-undecided Senate race between Republican Joe Miller and current Republican Senator Lisa Murkowski—who Miller beat in the primary and who then mounted a write-in campaign—may come down to a court challenge over the 92,500 write-in ballots cast. In his latest election-blog entry, Michael Alvarez—co-director of the Caltech/MIT Voter Technology Project—notes that, despite the brouhaha, 89 percent of the write-in voters somehow "managed to get Murkowski's name spelled correctly." Alvarez says that no matter which way this particular contest eventually goes, the real lesson may be in the success of the Murkowski campaign's efforts "to inform Alaskan voters how to cast a correct write-in ballot," and how that information might be used in the future by other campaigns in other states.

 

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The Polls Are Closed . . .

Calling last Tuesday's elections "historic" and "one of the most important midterm elections in recent memory," Caltech political scientist R. Michael Alvarez weighed in on the contrasts between the national and local results in an op-ed entitled, "GOP Tidal Wave Stopped at State Line," published in Sunday's Pasadena Star-News.

What made the difference? A number of factors, says Alvarez. "[I]t is likely that California's electorate on Tuesday was distinct from the rest of the nation," he writes. "As I visited polling places on Tuesday, in many parts of Los Angeles County there were energized voters, and visible voter-mobilization efforts. Early analysis of exit poll data indicates that those efforts might have led to a significant increase in Latino participation, another possible reason Republicans failed throughout the state."

To read more of Alvarez's analysis of the election results, go to the Pasadena Star-News. Or, for more research, analysis, and commentary on the election, visit the Caltech/MIT Voting Technology Project blog.

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What You See Affects What You Want

Visual attention guides the choices we make.

When it comes to making choices, say Caltech's Antonio Rangel and his colleagues, much depends on which items catch—and keep—your eye.

"We're interested in how the brain makes simple choices, like which item to pick from a buffet table," says Rangel, professor of neuroscience and economics. "Why is it that when we look at the buffet table, our gaze shifts back and forth between the items in order to make a choice? What is the role of visual attention in all this?"

To find out, Rangel—along with Caltech postdoctoral scholar Ian Krajbich and Stanford University's Carrie Armel—designed a mathematical model to describe the impact of what they call "visual fixation" on the making of these sorts of choices. (Simply put, visual fixation is the amount of time you spend gazing in one direction or at one item versus another.) They recently published their research online in the journal Nature Neuroscience.

"The model makes very specific predictions about how the pattern of fixation is related to our choices," Rangel explains. "For example, after controlling for other variables, items that are looked at more should be chosen more often."

But are they? To make sure, the team carried out an eye-tracking experiment in which subjects were shown pairs of food items on a computer screen, allowed to look at the items for as long as they wanted, and then were asked to choose one or the other. While the subjects gazed, the researchers tracked the movements of their eyes.

Just as predicted, the item a subject looked at longest was the one he or she most often picked—nearly three-quarters of the time, in fact.

Interesting stuff on its own merit, right? It also has implications for the business world—putting increased emphasis on things like packaging and in-store displays. "[T]he model explains how cultural norms (for example, reading left to right) can interact with comparator processes to produce cultural choice biases," the scientists write. "These biases help to explain, for example, why shelf and computer screen space on the top-left is more valuable than other positions."

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