Snap Judgments During Speed Dating

Caltech researchers identify two regions of the brain whose behavior predicts the outcome of speed dating

PASADENA, Calif.—For speed daters, first impressions are everything. But it's more than just whether someone is hot or not.

Whether or not we like to admit it, we all may make snap judgments about a new face. Perhaps nowhere is this truer than in speed dating, during which people decide on someone's romantic potential in just a few seconds. How they make those decisions, however, is not well understood.

But now, researchers at the California Institute of Technology (Caltech) have found that people make such speed-dating decisions based on a combination of two different factors that are related to activity in two distinct parts of the brain.

Unsurprisingly, the first factor in determining whether someone gets a lot of date requests is physical attractiveness. The second factor, which may be less obvious, involves people's own individual preferences—how compatible a potential partner may be, for instance.

The study, which is published in the November 7 issue of the Journal of Neuroscience, is one of the first to look at what happens in the brain when people make rapid-judgment decisions that carry real social consequences, the researchers say.

"Psychologists have known for some time that people can often make very rapid judgments about others based on limited information, such as appearance," says John O'Doherty, professor of psychology and one of the paper's coauthors. "However, very little has been known about how this might work in real social interactions with real consequences—such as when making decisions about whether to date someone or not. And almost nothing is known about how this type of rapid judgment is made by the brain."

In the study, 39 heterosexual male and female volunteers were placed in a functional magnetic resonance imaging (fMRI) machine and then shown pictures of potential dates of the opposite sex. They were given four seconds to rate, on a scale from 1 to 4, how much they would want to date that person. After cycling through as many as 90 faces, the participants then rated the faces again—outside the fMRI machine—on attractiveness and likeability on a scale from 1 to 9. Later, the volunteers participated in a real speed-dating event, in which they spent five minutes talking to some of the potential dates they had rated in the fMRI machine. The participants listed those they wanted to see again; if there were any matches, each person in the pair was given the other's contact information.

Perhaps to no one's surprise, the researchers found that the people who were rated as most attractive by consensus were the ones who got the most date requests. Seeing someone who was deemed attractive (and who also ended up with more date requests) was associated with activity in a region of the rater's brain called the paracingulate cortex, a part of the dorsomedial prefrontal cortex (DMPFC), which is an important area for cognitive control and decision making. The paracingulate cortex, in particular, has been shown to be active when the brain is comparing options.

This phenomenon was fairly consistent across all participants, says Jeff Cooper, a former postdoctoral scholar in O'Doherty's lab and first author of the paper. In other words, nearly everyone considers physical attraction when judging a potential romantic partner, and that judgment is correlated with activity in the paracingulate cortex.

"But that's not the only thing that's happening," Cooper adds. When some participants saw a person they wanted to date—but who was not rated as very desirable by everyone else—they showed more activation in the rostromedial prefrontal cortex (RMPFC), which is also a part of the DMPFC, but sits farther in front than the paracingulate cortex. The RMPFC has been previously associated with consideration of other people's thoughts, comparisons of oneself to others, and, in particular, perceptions of similarities with others. This suggests that in addition to physical attractiveness, the researchers say, people consider individual compatibility.

While good looks remains the most important factor in determining whether a person gets a date request, a person's likeability—as perceived by other individuals—is also important. For example, likeability serves as a tiebreaker if two people have equal attractiveness ratings. If someone thought a potential date was more likeable than other people did, then that someone was more likely to ask for a date.

"Our work shows for the first time that activity in two parts of the DMPFC may be very important for driving the snapshot judgments that we make all the time about other people," O'Doherty says.

As for the results of the speed-dating event? A few couples were still together six weeks afterward, Cooper says, but the researchers have not followed up. The study was focused on the neural mechanisms behind snap judgments—how those judgments relate to long-term romantic success, he says, is another question.

In addition to Cooper and O'Doherty, the other authors of the Journal of Neuroscience paper are Caltech graduate student Simon Dunne and Teresa Furey of Trinity College Dublin. The title of paper is "Dorsomedial Prefrontal Cortex Mediates Rapid Evaluations Predicting the Outcome of Romantic Interactions." This research was funded by an Irish Research Council on Science, Engineering, and Technology Fellowship, the Wellcome Trust, and the Gordon and Betty Moore Foundation.

Marcus Woo
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Tuesday, April 9, 2013
Avery Library – Avery House

Spring Teaching Assistant Orientation

Literature in the Middle Ages: An Interview with Jennifer Jahner

This fall, Jennifer Jahner joined Caltech as an assistant professor of English. As an undergraduate, she planned to study environmental science at Western Washington University. But as a lifelong reader, she couldn't elude the lure of literature, and she ended up majoring in English instead, receiving her BA in 1998. Afterward, she spent several years as a book editor before returning to academia as a graduate student at the University of Colorado, Boulder, where she took a seminar on medieval literature—a class that she says changed her life. Discovering a passion for the time period and for studying old, rare manuscripts, she got her MA in 2005 and then went to the University of Pennsylvania, where she received her PhD last spring. Jahner recently answered a few questions about her research and her thoughts on joining Caltech.

What do you study?

I study medieval England and particularly the relationships between legal writing and literary writing. My research looks at the writing, copying, and transmission of political lyrics, which are often short poems that try to tackle very thorny legal and political questions. What I look at are the legal ideas and discourses that these poems engage in, what sorts of manuscripts they are copied in, and what these poems can tell us about how people understood forms of community and legal obligation in the Middle Ages.

What's interesting about these poems?

One of the interesting questions about these poems is that, especially in England, they're anonymous. They survive in all sorts of settings, so they get copied into chronicles and they get copied on the flyleaves of manuscripts. They're in all sorts of languages. They're in English, they're in French, and they're in Latin. They suggest to scholars an educated milieu of readers who could understand those languages but who also were looking for entertainment, so they're propaganda pieces, they're advocating revolution against the king, they're condemning revolution against the king. They're interesting, but we don't know a lot about who wrote them or necessarily why.

How does your research straddle the line between history and literature?

Political poems in particular are interesting works for thinking about the difference between literature and history and how we mark something as literary and something else as historical. In fact, one of the reasons they don't tend to be talked about as much as other medieval texts is because they fall right on that boundary line and aren't actually very comfortable in either category.

They're poetic and they're clearly engaging in the conventions of poetic composition. They have rhyme. They have meter. They use allusions and metaphor. And they're very rich rhetorically. But their subject matter is intrinsically historical. They're talking about people and events that happened. They're talking about battles and political controversies. That means that for literary scholars, they're often thought of as somehow less literary than something that might be entirely invented. For the historians, they are useful to a degree as evidence of what people might have been thinking or talking about around a given event. But precisely because they're poetic and they're taking license with those events, they don't measure up to the standards of a true or trustworthy source.

What excites you about your work?

There's so much about the Middle Ages that we still don't know. There are so many texts that remain to be read, thought about, and edited. I love the fact that my job requires and allows me to look at things that are 600 or 700 years old that were copied out by hand and were bound by hand. I find the strangeness and unfamiliarity of the Middle Ages also really compelling. You can't take for granted any of your own assumptions about what it meant to read things, what it meant to listen to things. It's also just really hard. You have to know dead languages. I like the challenge of it.

What excites you about coming to Caltech?

Caltech is actually a really great place to be a humanist. My work tends to be interdisciplinary and it's really common for medievalists to be interdisciplinary because the period doesn't recognize the same boundaries that we do now. It's great to be at a place like Caltech, where our division is a de facto interdisciplinary department. We're made up of literature scholars, historians, and philosophers. It's an exciting place for me to be, because I get to work really closely in a daily setting with people who are doing different kinds of things from me, that are related in ways that I wouldn't necessarily expect.

The other thing that's great about being here is that it's a mile away from the Huntington Library, which is one of the premier manuscript and rare-book libraries in the world and has a terrific medieval-manuscript collection. I feel like I couldn't have landed in a better place.

Having to read and write so much for your work, do you still get to read for pleasure?

I read now less for fun than I ever have at any point in my life. But I will always have a novel on the bed stand. The reward for getting some project done is to relax with a book.

Marcus Woo
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Technology Has Improved Voting Procedures

New report assesses voting procedures over the last decade

PASADENA, Calif.—Thanks to better voting technology over the last decade, the country's election process has seen much improvement, according to a new report released today by researchers at Caltech and MIT. However, the report notes, despite this progress, some problems remain.

Spurred by the debacle of hanging chads and other voting problems during the 2000 presidential election, the Voting Technology Project (VTP) was started by Caltech and MIT to bring together researchers from across disciplines to figure out how to improve elections. The VTP issued its first report in 2001.

"Since that report came out and since our project was formed, a lot of progress has been made in improving how American elections are run," says Michael Alvarez, professor of political science at Caltech and codirector of the VTP.

For example, the report found that getting rid of outdated voting machines has caused a drop in the number of votes lost to ballot errors. To assess how many votes are lost in each election due to voting mistakes, the researchers calculate the number of residual votes—or the difference between the number of votes that are counted for a particular office and the total number of votes cast. If there are no voting errors, there should be no residual votes.

In their first report in 2001, the researchers found that older voting technology—like punch cards—led to a high residual vote rate. But their new research now shows that the rate has dropped. In particular, Charles Stewart III, a professor of political science at MIT and the other codirector of the VTP, and his colleagues found that the total number of residual votes decreased from 2 percent in 2000 to 1 percent in 2006 and 2008, meaning that fewer votes were lost due to voting errors. The drop was greater in states that instituted more modern voting technology.

"As we moved away from punch cards, lever machines, and paper ballots and towards optical scan systems and electronic systems that have voter verification, we have seen the voter residual rate plummet," Alvarez says. Voter-verification technology gives voters immediate feedback if they make a mistake—by filling in a circle incorrectly, for example—and a chance to correct their error to ensure that their votes are counted.

In addition, the report urges officials to continue and expand election auditing to study the accuracy of registration and voting procedures. For example, after an election, officials can recount ballots to make sure the electronic ballot counters are accurate. "Postelection ballot auditing is a great idea and states need to continue their efforts to use those election ballot-auditing procedures to increase the amount of confidence and integrity of elections," Alvarez says.

The researchers also describe concern with the rise of absentee and early voting, since voter verification is much harder to do via mail. Unlike with in-person voting, these methods offer no immediate feedback about whether a ballot was filled out correctly or if it got counted at all. Once you put your ballot in the mailbox, it's literally out of your hands.

The report also weighs in on voter-identification laws, which have been proposed in many states and subsequently challenged in court. Proponents say they are necessary to prevent voter fraud while opponents argue that there is little evidence that such fraud exists. Moreover, opponents say, voter identification laws make it much more difficult for people without government-issued IDs to vote. But, the report says, technology may resolve the conflict.

"Technology may help ensure voter authentication while alleviating or mitigating the costs that are imposed on voters by laws requiring state-issued identification," says Jonathan Katz, the Kay Sugahara Professor of Social Sciences and Statistics and coauthor of the VTP report.

For example, polling places can have access to a database of registered voters that is also linked to the state's database of DMV photos. A voter's identification can then be confirmed without them having to carry a photo ID. For voters who do not have an ID, the polling place can be equipped with a camera to take an ID picture immediately. The photo can then be entered into the database to verify identification in future elections.

Click here to read the complete report and learn more about the VTP.

In addition to Alvarez, Stewart, and Katz, the other authors of the Caltech/MIT VTP report are Stephen Ansolabehere of Harvard, Thad Hall of the University of Utah, and Ronald Rivest of MIT. The report was supported by the Carnegie Corporation of New York. The project has been supported by the John S. and James L. Knight Foundation and the Pew Charitable Trusts.

Marcus Woo

Handicapping the Election: An Interview with Erik Snowberg

Erik Snowberg—a Caltech professor of economics and political science who is an expert on the relationship between economics and politics—has more than an academic interest in politics: he was an intern for the House Committee on Science in 1998, worked for Ted Kennedy from 1998 to 1999 on immigration issues, and then ran for Cambridge City Council in 1999 when he was an undergraduate at MIT. Despite a record student voter turnout, he lost. After getting bachelor's degrees in mathematics and physics, he went off to Stanford to study economic policy, receiving a PhD in business in 2008, the year he joined the Caltech faculty.

With the election just about a month away, Snowberg recently answered a few questions about the presidential election and what we can expect on November 6.

The economy seems to be the major focus of the presidential election this year. How do you see it playing out? 

It is not a stretch to say that economics is the issue in every presidential campaign. Certainly in my lifetime, economics seems to have determined every election, with the exception of Bush versus Gore in 2000. While the economy was turning down then, we were still coming off a very long period of growth, and the economic models said that Gore should have won.

Now, we are in this middle ground where even though the overall level of the economy is awful, the economy has slowly been getting better over the past year. So the economic models we use to try to predict election outcomes based on economic fundamentals say we can't predict who is going to win.

You have studied people's perceptions of the economy and how that is affected by their economic situation. From that perspective, do you have any insights into this election?

I showed that people's perceptions of unemployment were largely grounded in their own experience. So, you can talk all you like about the economy, but that is not really going to change many people's minds; you can say that the economy is really doing great, but people who have many unemployed friends or family members are not going to feel that way. Or, you can say that the economy is doing terribly, but people who just got a big bonus are generally not going to feel that way. So, we are in this place where issues other than the economy might matter, such as the candidates' character.

With the election in the homestretch, there has been a tremendous amount of attention on the candidates' performances in the debates. Can debate performances decide elections?

Very rarely. Generally it has been the case that following a debate, the challenger gains on average two percentage points in the polls, which is not usually enough to be decisive. So it is difficult to tell if debates affect much of anything. The only recent time where a debate might have decisively influenced an election was in 1980 when Carter and Reagan debated about a week before the election. In that debate, Reagan famously asked voters, "Are you better off than you were four years ago?" The economy actually had not been doing too badly until Carter brought in Paul Volcker as chairman of the Federal Reserve in 1979. Inflation was fairly out of control at that point, and Volker clamped down on it, which damaged economic growth. So the economy had a downturn in Carter's last six months in office, and Carter paid the price.

In early October, the latest jobs numbers showed that unemployment has dropped below eight percent. While Obama has been claiming that the economy is getting better, Romney has argued that with his business background, he would be doing a much better job steering the economy. How do you see voters responding?

I don't have any particular reason to believe that people would think that a businessman would have any particular expertise in managing the economy. You could equally turn that around and ask, "Why isn't Obama assured of reelection because he is the only one running who has experience managing the entire economy?" It is not clear to me why voters would perceive it one way or another. Romney was in a type of business where the emphasis was not on creating jobs. It was on creating value for shareholders. If people are concerned about job growth, the guy who has a lot of experience making sure that capital gets a better return on investment is not necessarily going to be the guy they are going to choose for president.

Who do you think is going to win?

If I had to put money on it, I'd put money on Obama, based on the improvement in the economy. I have to say, Romney's performance in the first debate was amazing. But in general, surveys find that he has extremely low likeability ratings—lower than any challenger in a long time. 

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Friday, October 19, 2012
Beckman Institute Auditorium – Beckman Institute

Last Will. & Testament on Tour

Columbus to D'Ailly: Are We There Yet?

Christopher Columbus made a few mistakes in researching the route to Japan, his first intended destination on his famous 1492 voyage to the Indies. Among the worst: he ignored sound contemporary scholarship on the size of Earth, its continents, and its oceans in favor of estimates made by medieval theologian and cosmographer Pierre D'Ailly, who was born 101 years before Columbus. That error, along with others, shortened Columbus's estimate of the number of miles he should sail by so much that he was already antsy by the time the Bahamas saved him from a punishing lesson—learning how far away the Far East really is from Europe.

Why did Columbus put so much faith in D'Ailly? Perhaps because he stood to gain so much by it, claims Columbus expert and Caltech history professor Nicolás Wey-Gómez, who scrutinized Columbus's handwritten notes in D'Ailly's geographical treatise Imago Mundi. What Wey-Gómez saw in the margins, which Columbus annotated like a most assiduous student, calls into doubt any notion that this most-famous of seafarers sailed the ocean blue for purely exploratory reasons—that is, simply to reach the East by way of the West. In The Tropics of Empire: Why Columbus Sailed South to the Indies, Wey-Gómez revisits Columbus's attachment to the Imago Mundi, a treatise that was more than eight decades behind the times when Columbus set sail.

Wey-Gómez believes that Columbus saw a way to wealth and power in the application of medieval cosmography to his own travels, because D'Ailly did more than underestimate the longitudinal distance between the Far East and Europe. He also divided the world into polar, temperate, and torrid zones based on latitude and suggested that the characteristics of the people and land at any particular latitude would be the same at that same latitude anywhere on Earth. This was likely encouraging to Columbus, who had seen that the Portuguese commanded a lucrative trade in spices, dark-skinned slaves, and gold in the "torrid zone" in Africa—all of which Europeans took to be found specifically in tropical latitudes. So he headed south as much as west, in the hope of staking a claim to identical tropical "products" for Spain. According to Wey-Gómez's close reading of Columbus's navigational decisions and many other documents, including the discoverer's diary, Columbus aimed to sail south into the torrid zone after he'd reached Japan (which he believed to be much farther south than it is).

"Columbus was instead sorely disappointed," says Wey-Gómez, who is traveling around Columbus's old stomping grounds in Spain with the Caltech Associates this Columbus Day. The explorer found none of the "Indian" spices long coveted in Europe and very little gold in his Indies. The islanders, too, differed markedly in skin color from anyone he had seen in sub-Saharan Africa. Columbus never admitted that he hadn't reached the Far East, despite mounting evidence and a public belief that he had discovered a new continent, but he didn't quite find what he expected in America's tropics. "There seemed to be little relation between the general latitude, temperature, and 'nature' of the lands and peoples he had found in the Caribbean," says Wey-Gómez, "and this spelled trouble for someone attempting to replicate in the Americas Portugal's exploits in Africa."

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Caltech Again Named World's Top University in <i>Times Higher Education</i> Global Ranking

PASADENA, Calif.—The California Institute of Technology (Caltech) has been rated the world's number one university in the 2012–2013 Times Higher Education global ranking of the top 200 universities.

Oxford University, Stanford University, Harvard University, and MIT round out the top five.

"We are pleased to be among the best, and we celebrate the achievements of all our peer institutions," says Caltech president Jean-Lou Chameau. "Excellence is achieved over many years and is the result of our focus on extraordinary people. I am proud of our talented faculty, who educate outstanding young people while exploring transformative ideas in an environment that encourages collaboration rather than competition."

Times Higher Education compiled the listing using the same methodology as in last year's survey. Thirteen performance indicators representing research (worth 30 percent of a school's overall ranking score), teaching (30 percent), citations (30 percent), international outlook (which includes the total numbers of international students and faculty and the ratio of scholarly papers with international collaborators, 7.5 percent), and industry income (a measure of innovation, 2.5 percent) make up the data. Included among the measures are a reputation survey of 17,500 academics; institutional, industry, and faculty research income; and an analysis of 50 million scholarly papers to determine the average number of citations per scholarly paper, a measure of research impact.

In addition to placing first overall in this year's survey, Caltech came out on top in the teaching indicator as well as in subject-specific rankings for engineering and technology and for the physical sciences.

"Caltech held on to the world's number one spot with a strong performance across all of our key performance indicators," says Phil Baty, editor of the Times Higher Education World University Rankings. "In a very competitive year, when Caltech's key rivals for the top position reported increased research income, Caltech actually managed to widen the gap with the two universities in second place this year—Stanford University and the University of Oxford. This is an extraordinary performance."

Data for the Times Higher Education's World University Rankings were provided by Thomson Reuters from its Global Institutional Profiles Project, an ongoing, multistage process to collect and validate factual data about academic institutional performance across a variety of aspects and multiple disciplines.

The Times Higher Education site has the full list of the world's top 400 schools and all of the performance indicators.

Kathy Svitil
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Caltech Again Named World's Top University by <i>Times Higher Ed</i>
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Matthew Elliott: Modeling Networks

Matthew Elliott is Caltech's newest assistant professor of economics. Born in England, he earned his BA and MPhil from Oxford in 2002 and 2004. After receiving his PhD from Stanford in 2011, he spent a year at Microsoft Research in Cambridge, Massachusetts, before arriving in Pasadena this fall.

Elliott's research focuses on mathematically modeling different kinds of networks. For example, in networked markets, the interactions among players are constrained in a way that can be represented as a network. In a labor market, for instance, not everyone can be employed in every job, whether it's because they're not qualified, they don't have the requisite connections to get the job, or they simply aren't aware that there's an opening. Elliott distills this kind of complex system into its mathematical essence, developing theories that can eventually inform policy. His research is part of the Social and Information Science Laboratory, which is funded by the Gordon and Betty Moore Foundation and the Ronald and Maxine Linde Institute for Economic and Management Sciences. He recently spoke a little more about his work.

What's another example of a network market that you're trying to model?

Within this context of network markets, another thing you might think about is the production and sale of natural gas. The producer of natural gas can only sell its gas to another country if there's a pipeline between it and that other country. You can view the pipelines as a network that describes which countries can trade directly with which other countries. And a question you might be interested in is whether the network is built efficiently. Are there good incentives in place? What kind of inefficiencies would you expect and how bad can they be?

Does this analysis occur after the fact, or do you do this before you actually build the gas pipelines?

Most of the analysis is after the fact, and you're trying to explain what's going on. But by being able to explain things that have happened before, and why, you can hopefully understand a little better the problems that will arise in the future and try to avoid some of those inefficiencies.

What excites you most about your job?

I love doing what I do. It's the problem solving. You go to work and your job consists of playing with problems and trying to find solutions to them. I find it pretty remarkable that people pay me to do this—and it's not something I just do in my spare time.

Your research is very theoretical. But do you also work with real-world, empirical data? Or do you pass along your theories to someone else who can apply them?

Somewhere in between. A good example is a project on financial networks that I'm now working on with [Stanford economist and former Caltech professor] Matt Jackson and [MIT postdoc and Caltech graduate (BS '07)] Ben Golub. The idea is to model the network of financial relationships between either banks or countries and to understand the dependencies between them. What we want to know is, if one of those countries or banks receives some shock that's going to cause it to fail, how does that spread through the system? When does one failure lead to a contagion of other failures?

Sounds like something that's quite relevant today.

It's definitely a topical thing, and we're certainly not the only people working on this. A small part of that project is collecting data on European countries and their cross holdings. Then we try to see what our theory has to say when we apply it to the data.

I'm very aware that the research I do is very theoretical, and most of the time it isn't going to specifically be something that policymakers are going to read and take to heart. But I think my work does provide a framework for them to think about problems. I think it's exciting to be able to do that.

Marcus Woo
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Ready for Your Close-Up?

Caltech study shows that the distance at which facial photos are taken influences perception

PASADENA, Calif.—As the saying goes, "A picture is worth a thousand words." For people in certain professions—acting, modeling, and even politics—this phrase rings particularly true. Previous studies have examined how our social judgments of pictures of people are influenced by factors such as whether the person is smiling or frowning, but until now one factor has never been investigated: the distance between the photographer and the subject. According to a new study by researchers at the California Institute of Technology (Caltech), this turns out to make a difference—close-up photo subjects, the study found, are judged to look less trustworthy, less competent, and less attractive.

The new finding is described in this week's issue of the open-access journal PLoS One.

Pietro Perona, the Allen E. Puckett Professor of Electrical Engineering at Caltech, came up with the initial idea for the study. Perona, an art history enthusiast, suspected that Renaissance portrait paintings often featured subtle geometric warping of faces to make the viewer feel closer or more distant to a subject. Perona wondered if the same sort of warping might affect photographic portraits—with a similar effect on their viewers—so he collaborated with Ralph Adolphs, Bren Professor of Psychology and Neuroscience and professor of biology, and CNS graduate student Ronnie Bryan (PhD '12) to gather opinions on 36 photographs representing two different images of 18 individuals. One of each pair of images was taken at close range and the second at a distance of about seven feet.

"It turns out that faces photographed quite close-up are geometrically warped, compared to photos taken at a larger distance," explains Bryan. "Of course, the close picture would also normally be larger, higher resolution and have different lighting—but we controlled for all of that in our study. What you're left with is a warping effect that is so subtle that nobody in our study actually noticed it. Nonetheless, it's a perceptual clue that influenced their judgments."

That subtle distance warping, however, had a big effect: close-up photos made people look less trustworthy, according to study participants. The close-up photo subjects were also judged to look less attractive and competent.

"This was a surprising, and surprisingly reliable, effect," says Adolphs. "We went through a bunch of experiments, some testing people in the lab, and some even over the Internet; we asked participants to rate trustworthiness of faces, and in some experiments we asked them to invest real money in unfamiliar people whose faces they saw as a direct measure of how much they trusted them."

Across all of the studies, the researchers saw the same effect, Adolphs says: in photos taken from a distance of around two feet, a person looked untrustworthy, compared to photos taken seven feet away. These two distances were chosen by the researchers because one is within, and the other outside of, personal space—which on average is about three to four feet from the body.

In some of the studies, the researchers digitally warped images of faces taken at a distance to artificially manipulate how trustworthy they would appear. "Once you know the relation between the distance warp and the trustworthiness judgment, you could manipulate photos of faces and change the perceived trustworthiness,'' notes Perona.

He says that the group is now planning to build on these findings, using machine-vision techniques—technologies that can automatically analyze data in images. For example, one application would be for a computer program to have the ability to evaluate any face image in a magazine or on the Internet and to estimate the distance at which the photo was taken.

"The work might also allow us to estimate the perceived trustworthiness of a particular face image," says Perona. "You could imagine that many people would be interested in such applications—particularly in the political arena."

The study, "Perspective Distortion from Interpersonal Distance Is an Implicit Visual Cue for Social Judgments of Faces," was funded by grants from the National Institute of Mental Health and from the Gordon and Betty Moore Foundation.

Katie Neith
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When Judging Portraits, Distance Matters
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