Robert B. Cialdini, Ph.D. 

Dr. Robert B. Cialdini, Professor of Psychology at Arizona State University, has spent over fifteen years in the scientific investigation of the processes whereby people are persuaded and reach their decisions. He enumerates six fundamental social and psychological principles underlying the thousands of individual tactics that successful persuaders or compliance practitioners use every day to get us to say yes.

*These principles are:

Rule of Reciprocity 

Commitment and Consistency

People have a desire to look consistent within their words, beliefs, attitudes and deeds...this tendency is fed from three sources:

Social Proof 

One means we use to determine what is correct is to find out what other people think is correct. We view a behavior as more correct in a given situation to the degree that we see other performing it. The principle of social proof can be used to stimulate a person's compliance with a request by informing the person that many other individuals (the more, the better, the more "famous" the better) are or have been complying with it. This weapon of influence provides us with a shortcut for determining how to behave, but, as the same time, makes one who uses the shortcut vulnerable to the attacks of profiteers who lie in wait along its path (introduction seminars or guest dinners, retreats to recruit cult members--provide the models of the behavior the group wants to produce in the new recruit) Social proof is most influential under two conditions:


People prefer to say yes to individuals they know and like. This simple rules enables us to learn about factors that influence the liking process by examining which factors compliance professionals emphasize to increase their overall attractiveness and their consequent effectiveness. Compliance practitioners regularly use several such factors. One feature of a person that influences overall attractiveness is physical attractiveness. Although it has long been suspected that physical beauty provides an advantage in social interaction, research indicates that the advantage may be greater than supposed. Physical attractiveness seems to engender a "halo" effect that extends to favorable impressions of other traits such as talent, kindness, and intelligence. As a result, attractive people are more persuasive both in terms of getting what they request and in changing others' attitudes. A second factor that influences liking and compliance is similarity. We like people who are like us and are more willing to say yes to their requests, often in an unthinking manner. Another factor that produces liking is praise; although they can sometimes backfire when crudely transparent, compliments general enhance liking, and thus, compliance. Increased familiarity through repeated contact with a person or thing is yet another factor that normally facilitates liking. But this relationship holds true principally when the contact takes place under positive rather than negative circumstances. One positive circumstance that works especially well is mutual and successful cooperation. A fifth factor linked to like is mere association. By connecting themselves or their products with positive things, merchants of influence frequently seek to share in the positivity through the process of association. Other individuals as well appear to recognize the effect of simple connections and try to associate themselves with favorable events and distance themselves from unfavorable events in the eyes of observers. A potentially effective strategy for reducing the unwanted influence of liking on compliance decisions requires a special sensitivity to the experience of undue liking for a requester. Upon recognizing that we like a requester inordinately well under the circumstances, we should step back from the social interaction, mentally separate the requester from his or her offer, and make any compliance decision based solely on the merits of the offer


In the Milgram studies of obedience, we can see evidence of a strong pressure in our society for compliance with the requests of an authority. The strength of this tendency to obey legitimate authorities comes from systematic socialization practices designed to instill in society members the perception that such obedience constitutes correct conduct . In addition, it is frequently adaptive to obey the dictates of genuine authorities because such individuals usually possess high levels of knowledge, wisdom, and power. For these reasons, deference to authorities can occur in a mindless fashion as a kind of decision-making shortcut. When reacting to authority in an automatic fashion, there is a tendency to do so in response to the mere symbols of authority rather than to its substance. Three kinds of symbols that have been shown by research to be effective in this regard are

In separate studies investigating the influence of these symbols, individuals possessing one or another of them (and no other legitimizing credentials) were accorded more deference or obedience by those they encountered. Moreover, in each instance, those individuals who deferred or obeyed underestimated the effect of authority pressures on their behaviors. It is possible to defend ourselves against the detrimental effects of authority influence by asking two questions: Is this authority truly an expert? How truthful can we expect this expert to be here? The first question directs our attention away from symbols and toward evidence for authority status. The second advises us to consider not just the expert's knowledge in the situation but also his or her trustworthiness. With regard to this second consideration, we should be alert to the trust-enhancing tactic in which a communicator first provides some mildly negative information about him- or herself. Through this strategy the person creates a perception of honesty that makes all subsequent information seem even more credible to observers.


According to the scarcity principle, people assign more value to opportunities when they are less available. The use of this principle for profit can be seen in such compliance techniques as the "limited number" and "deadline" tactics, wherein practitioners try to convince us that access to what they are offering is restricted by amount or time. The scarcity principle holds true for two reasons:

The scarcity principle is most likely to hold true under two optimizing conditions

*Taken from Influence. Science and Practice, Robert B. Cialdini, Scott, Foresman and Company, 1985; Summary notes.