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Social-networking sites such as Facebook require users to find and confirm connections with other people. But what if your cell phone could automatically identify the people you know, and even sort them into categories?

If that capability arrives, it will be thanks to reality mining, a field that Tanzee­m Choudhury pioneered as a PhD student at the MIT Media Lab. Working at Intel after graduation, she created a pager-size sensor pack--loaded with software plus microphones, accelerometers, and other data-gatherin­g devices--to collect and analyze data about human interactions and activity. For instance, by processing verbal utterances, she can identify the most influential people in a social network.

Now an assistant professor of computer science at Dartmouth, Choudhury is conducting experiments with the sensor-laden iPhone. Within a few years, she says, simple versions of her software could be available for cell phones. --Kate Greene