YAHOO! for Winter Mason, PhD

• Current gig: Postdoctoral fellow, Yahoo Research Labs, Human Social Dynamics Group

• An unforeseen path: Mason studied cognitive science and social psychology at Indiana University. He stumbled into the science of social networks after collaborating on a paper with one of his graduate advisers on what kinds of social networks help groups most efficiently solve problems. "It was the perfect convergence of all my interests," says Mason, a mathematical modeling aficionado and computer whiz.

• Defining connections: Mason studies how we interact online and off. With his colleagues at Yahoo, he's developed a new way to define social relationships in a principled way. In the past, social network researchers arbitrarily decided how many interactions between two people were needed to indicate a real social tie. In contrast, Mason's research suggests that a more accurate threshold for a social connection can be found by using the relationships to make predictions about the people, such as whether they're faculty or grad students. "Using this really simple, really dumb method of changing the definition of a social tie and using it to make predictions, you actually get at something that's probably indicative of a real social tie," he says. This line of research could help companies better target their advertising or even assist federal agents in hunting down terrorists, he says.

• Six degrees of separation: Mason is now exploring how to predict a person's success by his or her position in a social network. "If I'm focusing on a blogger, for instance, we define success to be how many comments their posts receive," he says. The more social connections a person has, the more likely many people will read and comment on his or her posts—just about what you'd expect, Mason says. However, he's also finding that bloggers with small, close-knit groups of friends also get many comments, as do people with small groups of well-connected friends.

• Last Facebook friend count: "Just 359—but I know every one of those people," Mason says.

• Renaissance researcher: As a lone psychologist in an office full of computer scientists, programmers, software engineers, economists and sociologists, Mason has learned to bridge disciplines. "I presented an economics paper at a computer science conference, I'm working on a computer science paper for a sociology journal, and I can even do a little programming now," he says.

• What's next: Mason is debating whether to return to academe or stay in industry. "There are plenty of opportunities for social networking psychologists like me," he says, especially at social-media-focused companies such as eHarmony and Facebook. Or he could stay where he is: Yahoo Labs announced that they are hiring more social scientists like Mason to help them discover the motivations behind Yahoo users' online behaviors. "Yahoo Research is a very cool place," Mason says.

—P. Worth