Behind the apps, games, and social media is a whole crew of folks whose job is to make their products feel essential. Many of the techniques they use are ones outlined by experts in human behavior, including Nir Eyal author of Hooked: How to Build Habit-Forming Products and BJ Fogg of Stanford University's Persuasive Technology Lab. Harris argues that these methods "hijack" our own good judgment. Most teens care deeply about peer validation, for example. So it makes sense that friends' feedback on social media -- both the positive and the negative -- would tug at you until you satisfy your curiosity. You have a phone in your pocket, so why not check now? And now. And now?