A group of 3,000 ordinary citizens, armed with nothing more than an Internet connection, is often making better forecasts of global events than CIA analysts. Here, a man crosses the CIA logo at its headquarters in Langley, Va. Saul Loeb/AFP/Getty Images hide caption

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Having a perfect memory can put a strain on relationships, because every slight is remembered. Katherine Streeter for NPR hide caption

itoggle caption Katherine Streeter for NPR

Ellie is a computer simulation designed to engage real people in meaningful conversation and take their measure. The computer system looks for subtle patterns in body language and vocal inflections that might be clues to underlying depression or other emotional distress. YouTube hide caption

itoggle caption YouTube

Jillian Blenis, 30, of Boston reacts while stopping at a makeshift memorial to marathon bombing victims Wednesday. Julio Cortez/AP hide caption

itoggle caption Julio Cortez/AP

Researchers say that aggressive people tend to interpret ambiguous faces as reflecting hostility. iStockphoto.com hide caption

itoggle caption iStockphoto.com

When anthropologists tallied the use of emotional words through a century of literature, they included many books without clear emotional content — technical manuals, for example, and automotive repair guides. Steve Debenport/iStockphotography hide caption

itoggle caption Steve Debenport/iStockphotography