Is there an angel or a devil behind the mask? Scientists say it may not matter in terms of anonymous behavior. Joel Saget/AFP/Getty Images hide caption

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Abraham Lincoln, circa 1850. Lincoln was a political non-entity before he was elected. Why is he more widely known to history than the presidents who came immediately before and after him? Hulton Archive/Getty Images hide caption

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Matt Langione, a subject in the study, reads Jane Austen's Mansfield Park. Results from the study suggest that blood flow in the brain differs during leisurely and critical reading activities. L.A. Cicero/Stanford University hide caption

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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

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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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