An incentive system that gave bonuses to teachers upfront, with the threat of having to give the money back if student performance didn't improve, proved effective in one study. David Franklin/iStockphoto.com hide caption

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Megan Lutz, left, and Justin Chun react to amateur comedian Robert Lynch at the Metropolitan Room in Manhattan, N.Y. Lynch is an anthropologist researching what laughing reveals about us. Melanie Burford for NPR hide caption

itoggle caption Melanie Burford for NPR

Who's The Happiest? Researchers studied photos of Olympic medalists to learn who is the happiest. Here, bronze medalist Aliya Mustafina of Russia, gold medalist Gabby Douglas of the U.S., and silver medalist Victoria Komova of Russia pose after the all-around gymnastics final. Julian Finney/Getty Images hide caption

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Can You Help Me Tie My Shoe? Researchers found that when study participants were asked an unusual request, they were more likely later on to perform a favor. iStockphoto.com hide caption

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Traffic rolls past a speed limit sign in Ohio. Researchers believe they have found a new way to encourage drivers to stay within a safe driving speed: giving them a financial reward that diminishes as they speed. Mark Duncan/AP hide caption

itoggle caption Mark Duncan/AP

Parents can make a difference in whether their kids become spenders or savers, studies find. iStockphoto.com hide caption

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President Bush and then-Democratic presidential nominee John Kerry shake hands at the end of a presidential debate in 2004 in St. Louis. Researchers want to better understand why partisans' views of the facts change in light of their political loyalties. Charlie Reidel/AP hide caption

itoggle caption Charlie Reidel/AP