Why do some ideas, products, news stories and trends spread like wildfire, while others disappear? Jonah Berger, PhD, discusses the science of what catches on; the psychological forces that drive word of mouth, including social currency and high-arousal emotions like awe and anger; whether online and offline sharing differ; and what his research can tell us about the spread of misinformation. Learn more about your ad choices. Visit megaphone.fm/adchoices