Sunshine Hillygus discusses Cambridge Analytica on Marketplace Tech podcast

“Microtargeting is not something that’s new,” said Sunshine Hillygus, a professor of political science and public policy at Duke University, referring to the process of using personal information to craft personalized messages. She said the practice goes back to the late 1990s, but it was happening on postcards and through direct mail. Campaigns would maintain detailed “voter files,” but all the information was offline. Then Facebook came along.

“It has been with Facebook that you have connected offline and online identities,” Hillygus said. “Now what campaigns can do is give a list of people that they have identified within the voter files, and using consumer data, they've identified the subset of gun owners in Pennsylvania who appear to care about a certain given issues. And because so many people are using Facebook, they can submit that list of names, these online identities, to Facebook and target them online.”

She said that before Facebook allowed that level of individual targeting, campaigns would simply have to guess at likely social media ad success. That’s essentially what the Obama campaign was doing in 2012.

“You would find that the advertisements from Obama that were put on women’s focused websites tended to be more likely to mention women’s issues,” she said. “But it wasn't the type of really, really individualized targeting that that you can do on Facebook.”