Robert Cialdini is an American psychologist, author, speaker, and professor. He has authored several books and is best known for writing his book on persuasion and marketing Influence: The Psychology of Persuasion, which was listed on the New York Times business best seller list, and Fortune Magazine lists the book in their “75 smartest books on business.” His other two books Yes! 50 Scientifically Proven Ways to be Persuasive, and The Small BIG: Small Changes That Spark a Big Influence were on bestselling lists in both the New York Times and The Times.