As we kick off a new season of Proof, we dig into the psychology and science behind our fascination with food shapes. From popcorn to square watermelons, you'll learn that there's a reason behind the choices we make when it comes to what our food looks like. Eliza Rothstein reports. Try making your own sweet and salty popcorn at home, with our recipe for Spicy Caramel Popcorn. Get a 14-day free trial for an America’s Test Kitchen digital subscription here. See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info. Learn more about your ad choices. Visit megaphone.fm/adchoices