Influence: Science and Practice () is a psychology book examining the key ways people can be influenced by "Compliance Professionals". The book's author is Robert B. Cialdini, Professor of Psychology at Arizona State University. The key premise of the book is that in a complex world where people are overloaded with more information than they can deal with, people fall back on a decision making approach based on generalizations. These generalizations develop because they allow people to usually act in a correct manner with a limited amount of thought and time. However, they can be exploited and effectively turned into weapons by those who know them to influence others to act certain ways. A seventh lever on "unity" has been added to the most recent edition. The findings in the book are backed up by numerous empirical studies conducted in the fields of psychology, marketing, economics, anthropology and social science. The author also worked undercover in many compliance fields such as car sales and door-to-door sales. Seven Principles of Influence Reciprocation People generally feel obliged to return favors offered to them. This trait is embodied in all human cultures and is one of the human characteristics that allow us to live as a society. Compliance professionals often play on this trait by offering a small gift to potential customers. Studies have shown that even if the gift is unwanted, it will influence the recipient to reciprocate. A variation on this theme, known as the "door-in-the-face technique", is to ask for a particularly big favor. When this is turned down, a smaller favor is asked for. This is likely to be successful because a concession on one side (the down-scaling of the favor) will be reciprocated by a concession by the other party (agreement to the smaller favor). Reciprocation is an application of reciprocity. Commitment and consistency People have a general desire to appear consistent in their behavior. People generally also value consistency in others. Compliance professionals can exploit the desire to be consistent by having someone make an initial, often small, commitment, known as the "foot-in-the-door technique". Requests can then be made that are in keeping with this initial commitment. People also have a strong desire to stand by commitments made by providing further justification and reasons for supporting them. Compliance professionals exploit this with the so-called "low-ball" technique, where buyers agree to an attractive offer before it is altered