to discuss this, we're joined by charles penner, a partner at jana partners, and by jean twenge, a sango state university psychology professor and the author of "igen: why today's super-connected kids are growing up less rebellious, more tolerant, less happy-- and completely unprepared for adulthood." thanks to you both for joining us. dr. twenge, let me begin with you. i think i know the answer from what the title of your book, but what can you tell us about what the research says about kids and iphones? >> so i-gen is the first generation to spend their entire adolescence with smartphones. that's had ripple effects across many areas of their lives. one place that's showing up is in their mental health. so right around 2012 in the big samples of teens, there was a sudden and pretty large jump in symptoms of depression and anxiety and clinical-level depression and suicide among teens. and that happened right at the same time that smartphones became common. so there's also lots of studies showing links between mental health issues and time spent on electronic devices such as smartphones

jean twenge's research found in 2012 the proportion of americans with smartphones exceeded 50%, thereere abrupt negative changes in teen behavior and emotional states. dr. twenge is a professor in personality psychology at san diego state university. she has studied generational differences for 25 years, and she helped draft that letter. dr. twenge, welcome back. help me provide the cliff notes version of your book to my audience why. >> "igen" is the generation born 1995 and later. they are the first generation to spend their entire adolescence with smartphones, and that's had ripple effects across many areas of their lives, so they spend of course a lot more time on their phones, and online and they spend less time with their friends in person, and that's really not a great combination for mental health. >> the graphs from your book tell quite a story and i'm going to flip through them in rapid succession. less dating. less driving. less hanging out. less sex, which in and itself might seem like a good thing from a parent's perspective, but i would argue, not in this context. less s