“Kaptein and Eckles set up an experimental online bookstore and encouraged customers to browse the titles and mark a few for purchase. By alternating the types of pitches—Appeal to Authority (“Malcolm Gladwell says you’ll like this”), Social Proof (“All your friends on Facebook are buying this book”), and the like—Kaptein and Eckles could track which mode of argument was most persuasive for each person.”—Welcome to the Brave New World of Persuasion Profiling | Wired Magazine