Fans of sports underdogs have had an amazing run these past few months. In February, the New Orleans Saints won their first-ever Super Bowl, an upset victory over the invincible Colts. At the beginning of April, a little-known college from the Midwest made it to the NCAA basketball title game against the hated Blue Devils. (When the kids from Butler finally lost, the papers called them “triumphant in defeat.”) And more recently, the Oklahoma City Thunder very nearly forced the defending champion Los Angeles Lakers to a seventh game in the first round of the NBA playoffs.

Reason tells us this run will soon be over—underdogs are underdogs because they usually lose. I wasn’t the only one whose heart sank when Butler’s final shot rimmed out, and I won’t suffer alone when Oklahoma City gets bumped from the playoffs. We all share in the occasional joy—and more frequent misery—of rooting for the improbable.

Case in point: I cheered for Butler, ranked No. 5 in their region, as the long shot against Duke, ranked No. 1. But a few days before, when the Bulldogs had played another five seed, Michigan State, I didn’t know which team was the underdog. The only solution was to root for the side that happened to be losing. Soon I found myself cheering for a Spartans team that couldn’t get it together in the second half. They made a late run—closing to within one point in the final minute—but, alas, my disappointment was guaranteed. (If Michigan State had come back, I would have been pulling for Butler.) When the game ended, I fell into a sour mood.

“What did you expect?” my girlfriend asked, later that night. Rooting for the little guy is the American way, I said. It’s Horatio Alger and Rocky Balboa and the Miracle on Ice. It’s human nature.

That didn’t quite answer her question. What’s so natural about our love for the underdog? Why do sports fans choose to suffer?

In 1992, an Indiana University professor named Edward Hirt conducted a famous study on the psychology of sports fandom. One hundred sixty-seven undergrads were invited into the lab and shown a broadcast of a Hoosiers basketball game. Afterward, they were asked to throw Velcro balls at a target, solve anagrams, and rate their chances of getting a date with members of the opposite sex.

Hirt showed that by varying the outcome of the basketball game, he could influence the results of the study. The students’ test scores had little to do with the Hoosiers’ performance on the court. But when they were asked how they felt about the tests, the basketball game made a huge difference. Big-time Indiana fans were more confident in their skills following a home-team victory—they expected to ace the ball toss and anagrams and declared themselves more sexually desirable. When the Hoosiers lost, the reverse happened: Students were dejected and lacking in self-esteem. Clearly there were real costs associated with sports fandom—a defeat on the court felt like a personal failure.

Researchers have found plenty of support for what seems like an obvious notion: In sports, we’re drawn to a winner. Other factors—like where you live and who your friends are—can influence your choice of a favorite team. (Why else would you root for the Chicago Cubs?) But “team success is kind of like the icing on the cake,” says Daniel Wann, a Murray State psychologist who studies the causes and consequences of being a fan.

Which brings us to that peculiar situation, so common in college basketball, where too much icing ruins the cake. In 1991, a pair of researchers at Bowling Green State University, Jimmy Frazier and Eldon Snyder, published a paper on what they called “the underdog concept in sport.” Frazier and Snyder posed a simple hypothetical scenario to more than 100 college students: Two teams, A and B, were meeting in a best-of-seven playoff series for some unidentified sport, and Team A was “highly favored” to win. Which team would the students root for?

Eighty-one percent chose the underdog.

Then the students were asked to imagine that Team B had somehow managed to win the first three games of the series. Would the subjects root for the sweep or switch allegiance to the favorite? Half of those who first picked the underdog now said they’d support Team A. It was the same, cockamamie approach I’d taken to Butler and Michigan State: Root, root, root for the losing team—no matter what.

If watching your team go down makes you feel like garbage, why are we drawn to teams that seem destined to lose? Frazier and Snyder tried to explain the effect with a bit of emotional economics. The sports spectator might be seen as a hedonistic animal, they argued, always out to maximize her excitement. So long as she’s not beholden to any one team for sentimental reasons—she’s a life-long Royals fan, perhaps—then she’ll choose her rooting interest based on a rational calculation of costs and benefits.

Since a close game provides more entertainment than one that’s lopsided, the self-interested fan might, for example, choose to support whichever team happens to be behind on the scoreboard. That’s what I did in the Final Four: Instead of pulling for one side or the other, I hoped the game would go into triple overtime.

My strategy has an unfortunate side effect: The team you’re rooting for never wins. On account of that, it may be smarter to gamble your emotions on the team that’s most likely to reward you with a stirring victory—and that’s least likely to crush your soul. For Frazier and Snyder, that means betting on the underdog: If they win, it’s the greatest feeling in the world. And if they lose—well, you kind of knew that would happen all along. The same reasoning applies in reverse: If you’re pulling for the favorite, then a loss cuts extra deep, while a victory merely delivers what you thought you deserved. “Thus a utilitarian model would indeed predict the underdog effect,” the authors observe.

Let’s give this a closer look. In effect, Frazier and Snyder are saying that the expected value of a bet on an underdog—its average payoff in raw, chest-bumping excitement—will always be higher than the expected value of a bet on the favorite. In other words, if you multiplied the odds of an underdog victory by the amount of pleasure it would produce, you’d end up with a higher number. Let’s say you were rooting for the Giants against the Patriots in Super Bowl XLII. The odds against the Giants were something like 4-to-1—meaning that bettors saw New York as being about one-fourth as likely to win the game as New England. Now imagine that the Giants’ remarkable upset turned out to be four times more gratifying for Giants fans than a corresponding victory would have been for Patriots fans. (I remember that game. It did feel pretty darn good.) If that’s the case, the expected payoffs would have been exactly the same. As a matter of emotional economics, it wouldn’t matter which team you were rooting for.

The hedonistic sports fan would be drawn to the underdog only if these numbers were out of whack—if the amount of joy associated with an upset were disproportionate to the odds. Imagine, for example, that a Giants upset were one-fourth as likely as a Patriots victory but 10 times more gratifying. In that case, rooting for the long shot would be a no-brainer. (Even the folks in Boston might get on board.) But to assume that an upset would confer some dazzling, disproportionate joy begs the question altogether: What makes the underdog so wonderful to begin with?

Here’s an alternative to Frazier and Snyder’s utilitarian model. Let’s assume the pleasure of an upset is exactly proportional to its odds: If Butler were half as likely to win the NCAA Championship, then a Bulldogs victory would feel twice as good. Now imagine that we all convinced ourselves, for one reason or another, that Butler had some hidden advantage that didn’t show up in the Vegas betting line. Maybe it was the team’s unbreakable heart or its selfless coach. If we gave our own inflated odds to the underdog but expected the reward would be undiminished, then betting on the long shot would make perfect sense. An emotional investment in Butler would look like a rational choice.

Researchers have found evidence for exactly this phenomenon—called the “favorite-long-shot bias”—at the horse track. One recent study that compiled stats from some 6 million American horse races showed a steep drop-off in the return on winning bets, as the odds against those bets increased. In other words, bettors were throwing money at the underdogs and underbidding on the favorites. That’s not because we get some special pleasure from playing the ponies at 100-to-1, the authors argue. It’s because we tend to overestimate the long shots’ chances.

This bias might be explained by a tendency that behavioral economists have labeled the “availability heuristic“: We make judgments about probability based on whatever data spring most easily to mind. The examples you remember are the ones that influence your beliefs. If you’ve just watched hours of footage about 9/11, for example, you might think you’re more likely to die in a terrorist attack than in a car accident.

It’s easy to see how the availability heuristic might lead us to favor the long shot. When you think about horse racing, which comes to mind first: Seabiscuit’s underdog victory in the 1938 Pimlico Special or Cool Coal Man’s unremarkable loss at the 2008 Kentucky Derby? If you’re thinking about Seabiscuit when you step up to the betting window, you’ll be more inclined toward horses with long odds. The same goes for any other sport. We’ll reminisce about the fifth-seeded Butler Bulldogs for years to come. But what about Temple and Texas A&M—similarly ranked teams that didn’t make it through the first weekend of the tournament? And consider all the other underdogs in our culture—from the Bible, from literature, and from every sports movie ever made. It’s no accident that we remember the Titans.

So how biased are we? A few years ago, a graduate student named Nadav Goldschmied decided to find out. Goldschmied, who’s now a professor of psychology at the University of San Diego, invited students to read a fake newspaper article about an upcoming rugby match. According to the article, odds makers had given one of the teams just a 30 percent chance of victory. When asked to make their own predictions, the students were more optimistic. Instead of pegging the underdog’s odds at 30 percent, they guessed it was more like 41 percent. If the article specifically referred to the disadvantaged team as an “underdog,” the effect was even stronger, with the students pegging the chance of victory at 44 percent.

Goldschmied repeated the experiment twice more, replacing the rugby teams with mayoral candidates and then a pair of businesses competing for a contract. In each case, the results were the same: The mere act of labeling one side as an underdog made the students think they were more likely to win.

A purely economic theory of underdogs doesn’t satisfy Goldschmied, though, nor does it appeal to his former mentor, Joseph Vandello of the University of South Florida. Their work has shown that our love for the little guy is as much a judgment of character as an emotional investment. In one study, they found that two-thirds of all voters in the 2004 presidential election described their preferred candidate as the “underdog.” A follow-up four years later revealed that presidential candidates were deemed more likable after being characterized as an “underdog” by someone else. More recent data from Vandello’s lab suggest that being cast as the underdog can make your actions seem more virtuous and your face appear more beautiful.

Why is an underdog so attractive? It may have something do with how hard he tries. Vandello showed subjects a video clip of a basketball game between two international teams said to be playing for a championship. One side was described as the 9-to-1 favorite, having won each of 15 previous playoff matches. After viewing the footage, which showed a close game, students were asked to rate the players according to their ability and effort.

As a rule, the underdogs were characterized as having less “talent” and “intelligence” than the favorites but more “hustle” and “heart.” That was true even when subjects viewed the same video clip with the labels reversed. It didn’t matter what was actually on the screen—which players jumped higher or who dived for the loose balls. The test subjects attributed more effort to whichever team had the underdog label.

So here’s another theory of the underdog effect: We like it when people try as hard as they can. A mediocre team with a lot of “heart” is more appealing—and thus more deserving of our fandom—than a lineup of distractible superstars.

But there’s one problem with this idea: In real-life competition, underdogs don’t seem to have any more gumption than the odds-on favorites. In fact, recent data suggest that the underdogs might be dogging it.

For a study published in January, researchers Nathan Pettit and Robert Lount tested a bunch of undergraduates on a simple cognitive task—their ability to generate possible uses for a knife. Some students were told their scores would be compared with scores from a similar experiment conducted at a more prestigious university, while others believed they were going head-to-head with students at a worse school.

The subjects who believed they were up against the stronger competition ended up performing worse on the test. Playing the role of the underdog appeared to sap their motivation. Likewise, the group that was ostensibly paired with a lower-ranked school seemed to try harder.

Another paper, by economist Jennifer Brown, used the results of hundreds of PGA golf tournaments to arrive at a similar conclusion. She examined how the performance of professional golfers changed when they were playing against Tiger Woods. Controlling for the course, the weather, and other factors, Brown found that Tiger’s opponents shot almost a full stroke worse, on average, whenever he was in the tournament. (The quality of Tiger’s game also made a difference: When he was on a roll, the competition suffered all the more.) Brown calls this an “adverse superstar effect”: In the face of a superior opponent, pro golfers have less incentive to compete. excellent write-up for the Wall Street Journal. Maybe Tiger's opponents are trying too hard, he says, with all that added pressure leading them to “choke” on the green. A choking effect could also explain the Pettit and Lount study—students who were up against the better school might have frozen up. But I'm not sure there's such a clear line to be drawn between quitting and choking. In any event, the conventional wisdom holds that the favorite is more likely to choke, not the underdog. The long shot can play fast and loose; he's got nothing to lose”>

Whether or not the underdogs are really trying harder, what’s important is how they’re perceived. And for some reason, we tend to assign positive attributes to whichever team or players are at a disadvantage. The utter ubiquity of this effect is part of what makes it so remarkable. Vandello has found that between two-thirds and three-quarters of us are prone to its influence, regardless of gender, political orientation, or personality type. And it applies in areas as diverse as sports, international relations, product branding, and the dating market. One group has even documented a preference for underdog landscape painters.

Even Frazier and Snyder, purveyors of the emotional economics model, wondered whether their findings might reflect some more noble human drive. What if it’s not a cost-benefit curve that attracts us to the underdog? Maybe he appeals instead to something deeper—a primal sense of fairness. It’s the ancient emotion aroused by the story of David and Goliath: We just want David to have a shot.

The desire for equity (or the aversion to inequity, as it’s more often formulated) could explain our strange attachment to the losing team. Economists have shown that people are willing to sacrifice their own interests for the sake of restoring balance. A well-known example comes from the laboratory game “Ultimatum.” Two players are presented with a pool of money, and the first proposes a way to split it—say, 60-40. The second player then decides whether to accept the offer. If she turns it down, neither one gets any money. It seems like no one should ever reject the offer, since that means forgoing something for nothing. But in practice, the idea of an uneven reward drives people crazy. We’d rather give up our share altogether.

The same idea might apply to sports fans. A lopsided championship game makes us uncomfortable; it seems unfair. The underdog effect, then, serves as ballast for crooked odds. If we’re at the stadium, we might use our fandom to influence the game directly—by screaming over the snap count or waving thundersticks at a free-throw shooter. And when we’re watching at home, our efforts to help the underdog might take the form of magical thinking: If I just cross my fingers …

Our dislike for inequity in sports could explain why we appreciate teams that appear to try harder on the court. Natural talent is unfair: You either have it or you don’t. But a game that’s decided on effort alone gives everyone an equal shot. The Bulldogs may not be as gifted as the Blue Devils, or as smart or well-coached. So we’re hoping a little elbow grease can even things out.

Vandello and Goldschmied set up an experiment to test this hypothesis. They started by presenting their subjects with the classic underdog scenario: Two teams, A and B, are about to play an important match, for which Team A was the odds-on (7-to-3) favorite. Then they made things more complicated. The students were to imagine that the players on Team A had lower salaries than the ones on Team B—their payrolls were $35 million and $100 million, respectively. Which team would the students root for—the small-market team that was a heavy favorite? Or the big-market team that was expected to lose?

Two-thirds supported the favorite, Team A. When two kinds of underdogs went head-to-head, the students came out in favor of the one with better odds but less money. For the authors, this was evidence that inequity aversion drives the underdog effect, “above and beyond” emotional self interest.

Indeed, Vandello suspects that a sense of fairness may be an evolved trait that isn’t specific to humans. He cites a Nature study from 2003, showing that brown capuchin monkeys reject unequal rewards for the same trained behavior: When one monkey was given a piece of cucumber and another received a delicious grape, the first became uncooperative. In 2008, similar findings were reported with canine subjects: One dog might refuse to offer her paw if deprived of the sausage treat offered to another. Like the people who play the Ultimatum game, these animals were ready to give up their share if they didn’t get a fair shake.

Not everyone believes the results of these animal inequity studies. But if Vandello’s right, chimps, orangutans, and capuchins would share our love for the long shot. Better still: Dogs themselves might root for the ‘dogs.

The Hoosiers study showed that we’re more confident when our team succeeds—that victory gives us hope. Maybe that’s what we like about the long shot: I’m more like Butler than Duke; if they can win, so can I.

The same idea may explain why Americans in particular love an underdog. When you’re living in an unequal society, the long shot offers something precious—the belief that anyone can overcome his misfortune. (Here’s the Marxist critique of college basketball: It blunts the anger of the working class.) The average American roots for the underdog in sports because he’s an underdog in life.

So how does the rest of the world respond to a sports mismatch? Vandello says monkeys and chimps might share our proclivity for long odds. What about the French and the Chinese?

At first glance, the underdog effect appears to be widespread. In 2004, for example, a runty chestnut mare named Haru-urara became a national hero in Japan after losing a record 113 consecutive races. But few have tried to study the question in a systematic way.

Two research groups have conducted surveys in the Far East, finding that people in Singapore and South Korea have more or less the same love for the long shot as Americans. Nadav Goldschmied has more specific cross-cultural data: He presented subjects in Israel, China, and Japan with the same hypothetical scenario he’d posed to students in the United States. When they were forced to choose sides, 72 percent of the Japanese and 57 percent of the Chinese picked the team that was at a disadvantage. The Americans fell somewhere in between, at 67 percent. Meanwhile, the weakest effect turned up among the Israelis, who chose the underdog just 52 percent of the time.

It’s not clear why the underdog effect might be subdued in Israel. One possible explanation has to do with a sociological measure called power distance, in which Israelis happen to rank near the bottom of the world. That means they’re exquisitely sensitive to social inequality, as compared with people in other countries.

For Goldschmied, though, the data showed an effect that was largely consistent across cultures. The underdog, he says, is a global phenomenon.

For all its globetrotting, the underdog effect can be a fickle thing. Sure, I rooted for Butler, but I don’t recall ever having cheered against the Giants or the Knicks on behalf of some plucky long shot. I realize that upsets are exciting, but … Let’s go Mets!

Scott Allison, a professor at the University of Richmond, has a theory for why underdog fandom can seem a little flimsy. He calls it the “Wal-Mart effect.” We root for our neighborhood store when a mega-discounter moves in down the street. But when it’s time to buy a new television, we opt for the cheaper price. Mom and pop may win our heart, says Allison, but they’re not getting our money.

To test this idea, Allison’s lab presented a bunch of adults with another underdog hypothetical. This time a pair of companies were vying for a contract to test the drinking water in far-off Boise, Idaho. One was a large, well-established firm founded 30 years ago; the other was an eager startup. Which company would the subjects root for?

As expected, people were inclined toward the underdog. But the experimenters changed their minds by tweaking two key variables. If the subjects were told that the water in question might contain “cancer-causing mercury,” the underdog effect disappeared. And if the site of the water testing was changed from “Boise, Idaho” to somewhere in their own community, the results flipped altogether. In that case, the subjects started rooting against the underdog.

Our affinity for the lesser team “is a mile wide and an inch deep,” concluded the researchers. “We may feel morally good about rooting for the underdog, but our positive reaction is quite malleable.”

Could that be right? If so, it doesn’t really matter whether we’re cheering for the Bulldogs out of some convoluted self-interest or because we think they’ve got hustle and heart. It doesn’t matter whether we’re egging them on for the sake of fairness or because they remind us of ourselves. Our attraction to the underdog may not matter very much at all.

Perhaps that’s why the underdog seems most at home in the trivial world of team sports. With nothing much at stake, we’re free to indulge an idle preference for an upset. “At an unconscious level, we know we don’t take underdogs all that seriously,” says Allison. “We love them, but it’s a weak effect.”

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