Northeastern University assistant professors Dave Choffnes and Christo Wilson talk with Recode's Kara Swisher about their recent year-long investigation into a popular online conspiracy theory: Smartphones are secretly turning on their microphones to record conversations and serve us more targeted ads. Choffnes and Wilson say that although there have been a small number of apps that have surveilled users, they tested 17,000 of the most popular apps on Android and found that this doesn't happen; in fact, it doesn't need to. Although the theory may sound plausible, we provide a vast amount of information about ourselves through other means that can explain ads that feel eerily well-targeted to our lives. The researchers also explain some of the steps consumers can take to reduce these more mundane privacy violations and how app developers have reacted since their study was released.Learn more about your ad choices. Visit podcastchoices.com/adchoices