He is best known for his 1984 book on persuasion and marketing, Influence: The Psychology of Persuasion. Influence has sold over 2 million copies and has been translated into twenty-six languages. It has been listed on the New York Times Business Best Seller List. Fortune Magazine lists Influence in their "75 Smartest Business Books."
Cialdini's theory of influence in based on the principles of reciprocity, commitment and consistency, social proof, authority, liking, and scarcity.
§6 key principles of influence by Robert Cialdini
Reciprocity – People tend to return a favor, thus the pervasiveness of free samples in marketing. In his conferences, he often uses the example of Ethiopia providing thousands of dollars in humanitarian aid to Mexico just after the 1985 earthquake, despite Ethiopia suffering from a crippling famine and civil war at the time. Ethiopia had been reciprocating for the diplomatic support Mexico provided when Italy invaded Ethiopia in 1935. The good cop/bad cop strategy is also based on this principle.
Commitment and Consistency – If people commit, orally or in writing, to an idea or goal, they are more likely to honor that commitment because of establishing that idea or goal as being congruent with their self-image. Even if the original incentive or motivation is removed after they have already agreed, they will continue to honor the agreement. Cialdini notes Chinese brainwashing on American prisoners of war to rewrite their self-image and gain automatic unenforced compliance. See cognitive dissonance.
Social Proof – People will do things that they see other people are doing. For example, in one experiment, one or more confederates would look up into the sky; bystanders would then look up into the sky to see what they were seeing. At one point this experiment aborted, as so many people were looking up that they stopped traffic. See conformity, and the Asch conformity experiments.
Liking – People are easily persuaded by other people that they like. Cialdini cites the marketing of Tupperware in what might now be called viral marketing. People were more likely to buy if they liked the person selling it to them. Some of the many biases favoring more attractive people are discussed. See physical attractiveness stereotype.
Scarcity – Perceived scarcity will generate demand. For example, saying offers are available for a "limited time only" encourages sales.
Yes! 50 Scientifically Proven Ways to be Persuasive. Authors: Noah J. Goldstein, Steve J. Martin and Robert B. Cialdini. Simon and Schuster, 2008, ISBN 978-1-4165-7096-7.
Compliance with a request in two cultures: The differential influence of social proof and commitment/consistency on collectivists and individualists. Authors: Cialdini, R.B., Wosinska, W., Barrett, D.W., Butner, J. & Gornik-Durose, M. (1999). Personality and Social Psychology Bulletin 25, 1242–1253.
Cialdini, R. B., Sagarin, B. J., & Rice, W. E. (2001). Training in ethical influence. In J. Darley, D. Messick, and T. Tyler (Eds.). Social influences on ethical behavior in organizations (pp. 137–153). Mahwah, NJ: Erlbaum.
Kenrick, D. T., Neuberg, S. L., & Cialdini, R. B. (2002) Social Psychology: Unraveling the Mystery (2nd Ed.). Boston: Allyn & Bacon.
Guadagno, R. E., & Cialdini, R. B. (2002). On-line persuasion: An examination of differences in computer-mediated interpersonal influence. Group Dynamics: Theory, Research and Practice, 6, 38–51.
Sagarin, B. J., Cialdini, R. B., Rice, W. E., & Serna, S. B. (2002). Dispelling the illusion of invulnerability: The motivations and mechanisms of resistance to persuasion. Journal of Personality and Social Psychology, 83, 526–541.