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When fairness prevails

first_imgPhilosophers and scientists have long puzzled over the origins of fairness. Work by a group of Harvard researchers offers some clues, with the discovery that uncertainty is critical in the concept’s development.Using computer simulations of evolution, researchers at Harvard’s Program for Evolutionary Dynamics (PED) — including Director Martin Nowak, scientist David Rand, and junior fellow Corina Tarnita — found that uncertainty is key to fairness. Hisashi Ohtsuki from the Graduate University for Advanced Studies in Kanagawa, Japan, also contributed to the study. Their work was described in a Jan. 21 paper in the Proceedings of the National Academy of Sciences.“A number of papers have studied the evolution of fairness over the years,” said Rand, who will begin an assistant professorship at Yale this summer. “Our novel contribution was to take the effects of randomness into account. What we found was that as we turned up the uncertainty in our simulations, it fundamentally changed the nature of the evolutionary dynamic. The result was that in a world that has a lot of uncertainty, it actually became optimal to be fair, and natural selection favored fairness.”To model fairness, Rand and colleagues used the Ultimatum Game, which involves two players bargaining over a pot of money. The first player proposes how the money should be split. If the second player accepts the offer, the money is split as proposed; if the offer is rejected, the game is over and neither player gets anything.“The reason this game is interesting is that if you assume everyone is rational and self-interested, the second player should accept any offer, because even if they’re getting only one dollar it’s still better than nothing,” Rand said. “The first player should anticipate that, and should make the minimum possible offer.”The game almost never works that way, however.Instead, Rand said, many people will reject offers they believe are unfair. Earlier studies have shown that as many as half of players will reject offers of 30 percent or less — meaning they are effectively paying to retaliate against the other player for making such a low offer, or to stop the other player from getting ahead.“The proximate psychological explanation for why people behave this way in the Ultimatum Game is that they have a preference for fairness, and they’re willing to pay to create equality,” Rand said. “The question we were trying to answer was: Why? Why did we come to have those preferences?”Rand and his colleagues built a series of computer players, each of which had a specific strategy describing how much they would offer, and how much they would accept. Each round, all the computer players played the game with one another. Then they updated their strategies in a process similar to genetic evolution.“You can think of it as though the players that earned higher payoffs attracted more imitators. Players sometimes choose to change their behavior, and when they do, they copy the strategies of players who were more successful,” Rand explained. “It could also represent actual genetic evolution, where players with [a] big payoff leave more offspring. Either way, higher payoff strategies tend to become more common in the population over time.”By observing which strategies become dominant over multiple generations, the researchers were able to track how the system evolved, and saw that fairness offered players an evolutionary advantage, but only when uncertainty was factored into the system.To test whether these results would play out in the real world, Rand and colleagues used the online labor market Amazon Mechanical Turk to recruit hundreds of volunteers from around the globe. After playing the Ultimatum Game, participants were asked how easy it was for people in their community to determine who is, and who isn’t, successful.“We found exactly what the model predicted, which, I think, wouldn’t have been at all obvious had we not done the modeling first,” Rand said. “What we found is a correlation — the more uncertainty there is about who is successful and who isn’t, the more fair people are in the Ultimatum Game.”Understanding why that is, however, is trickier.“Think about a world where nobody is offering anything — everyone is completely rational and self-interested,” Rand said. “If you introduce a fair person into a world like that, they will do poorly, because they will make generous offers, and people will accept them. Other people, however, will make low offers to that person, and they will be rejected. As a result the fair person will never have the chance to succeed.”The same is true of a rational person in a generally fair world. Their low offers will be rejected, resulting in a poor payoff.So what happens if you assume that successful strategies are always successful and unsuccessful strategies are always unsuccessful, as previous studies have?“If you’re in a selfish world, the population can never leave that state, because the fair person is always at a disadvantage,” he said. “If you rely on these kind of deterministic dynamics, that first fair person is always going to die out and fairness as a strategy will never spread.“Whereas in a world where there’s uncertainty, when someone experiments with a fair strategy in a world of selfish people, they will still get a bad payoff, but sometimes just by chance that fair strategy might become more common in the population,” he continued. “And once it becomes common enough, the momentum switches and it’s better to be fair than selfish. That’s how it becomes the favored behavior.”This work was funded by support from the John Templeton Foundation.last_img read more


No. 5 USC making up for sluggish start

first_imgThere certainly was plenty reason for optimism.Opening the season ranked No. 2 and boasting three returning senior All-Americans to go along with a top-10 recruiting class, the USC women’s volleyball team’s expectations were quickly tempered.Pleasant surprise · Sophomore outside hitter Sara Shaw, pictured here on Sept. 23 against then-No. 1 California, has notched 15 kills thus far this season, leading the No. 5 Women of Troy to six straight wins after starting the season just 5-3 overall. – Luciano Nunez | Daily TrojanThe Women of Troy lost two of their first three matches, including a shocking upset to unranked Central Florida, and fell flat in a 3-0 sweep in their Pac-12 opener against UCLA in front of a record crowd of 5,385 at Galen Center, giving them a 5-3 overall mark — the first time USC had lost at least three of its first eight matches since 2005.“With our conference schedule starting so early this year, we didn’t have [time] to try different things,” USC coach Mick Haley said. “So we had to guess at some things in the lineup. It just seemed like we didn’t have the right combination out on the floor.”With his squad struggling, Haley decided to insert sophomore outside hitter Sara Shaw into the starting lineup in place of fellow sophomore Kirby Burnham, an outside hitter and opposite.So far, the move has paid immediate dividends.Shaw tallied a career-high 15 kills and led the team in hitting percentage (.481) to spark USC in a road sweep of then-unbeaten No. 4 Washington.“She’s a comfortable person for everyone to play with,” Haley said. “[Shaw] was instrumental in settling us down.”Since the UCLA loss, the Women of Troy have ripped off six conference sweeps in a row for the first time since 2003, when they won the NCAA championship.The streak includes victories over California and Stanford, who were ranked No. 1 and No. 2, respectively, at the time.“We were all just really pumped and excited going against these two good teams,” Shaw said. “We had nothing to lose at that point, so we just gave it all we got and had a good show.”Another unexpected source of offense has come from freshman middle blocker Hannah Schraer, who has started all season while sophomore middle blocker Alexis Olgard recovered from offseason knee surgery and a bout of mononucleosis.Schraer is ranked third in the Pac-12 in hitting percentage (.386) and is averaging 1.73 kills per set.“In the beginning, it was a little stressful just getting used to the speed of the game,” Schraer said. “Now as a team, we’re definitely more comfortable playing together.”Schraer’s numbers are nearly identical to Olgard’s, who ranked fifth in the Pac-10 with a .366 hitting percentage while also averaging 1.73 kills per set last year.“Usually, freshmen middle [blockers] can’t do what [Schraer] has done,” Haley said. “She’s really done an exceptional job. I have not had a freshman come in, other than Olgard last year, who has played like this.”Olgard played briefly last weekend against Colorado and Utah for her first appearances of the season, and Haley said she should be back to full speed by mid-October.Haley said he wants to give junior middle blocker Natasa Siljkovic some playing time when she returns from the injury and wants to work Burnham and other bench players back into the rotation.Haley is encouraged by the progress he’s seen over the past few weeks, but he knows that anything can happen from now until the NCAA title match in December.“We’ve gone on a nice roll, but we have two more months of the regular season yet to go,” Haley said. “My experience [as coach] says don’t get too excited this early, and don’t get too down. You just gotta stay with it and keep improving.”last_img read more