Volume 20, Number 6
September 2003

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By Robert B. Cialdini, Roselle L. Wissler, and Nicholas J. Schweitzer

Robert B. Cialdini is Regents' Professor of Psychology at Arizona State University. Roselle L. Wissler is a research fellow with the Arizona State University College of Law's Lodestar Mediation Clinic. Nicholas J. Schweitzer is a graduate student in social psychology at Arizona State University.

A substantial body of systematic research demonstrates that certain interactions can lead people to accept a proposal or comply with a request that they might otherwise reject. This research has identified six fundamental principles of influence. They do not involve the merits of the proposal or request itself, but the way in which it is communicated.

The principle of liking. People are more easily influenced by those they like. Although research has uncovered several factors that affect how much one person will like another, the most powerful and the easiest to implement is similarity. In a simple but telling demonstration of the effects of similarity on influence, researchers mailed a set of surveys to random individuals. These surveys were accompanied by a cover letter, which for some of the recipients was "signed" by a researcher with a name designed to be similar to the recipient's. Although identical in all other aspects, the surveys sent with similar names were completed twice as often as the others. If something as trivial as similarity of names can affect compliance with a request, imagine how much more compelling a meaningful commonality, such as a shared interest, group membership, or goal, might be. A mediator or negotiator should spend the time necessary to locate such parallels among relevant parties and bring them to the surface.

The principle of authority. People are more easily influenced by those they perceive to be legitimate authorities. This response makes great sense because legitimate authorities have typically attained their positions by virtue of greater knowledge or skill or experience in the matter at hand. But for all their specialized knowledge, these experts frequently act like novices in the domain of social influence by assuming that their expertise is self-evident. For instance, physical therapists at one hospital were concerned about their patients' compliance with their prescribed treatment plans. After being discharged from the hospital, many patients discontinued their therapy exercises, no matter how much the therapists stressed their importance. However, a simple intervention solved the problem. By hanging their numerous awards, diplomas, and certifications on the walls of their clinic, the therapists were able to raise compliance by 34 percent. In general, genuine authorities should establish their expertise before launching any influence attempt (e.g., in a letter of introduction). To be optimally persuasive, however, expertise is not enough; a communicator also must establish that he or she is a trustworthy source of information.

The principle of scarcity. The principle of scarcity provides that items and opportunities become more desirable as they become less accessible. As a result, an effective mediator or negotiator should never fail to describe the unique or otherwise unattainable advantages of any recommendation or offer. Moreover, research on the principle of scarcity has demonstrated that, in situations characterized by uncertainty, presenting these unique advantages as what stands to be lost by a failure to take action is more persuasive than emphasizing what stands to be gained by taking the action.

Mediators can emphasize the unique benefits of mediation that the parties will lose if they do not mediate or if they do not settle in mediation (e.g., the parties would lose the assistance of a neutral third party to resolve the dispute, they would lose the opportunity to design a resolution tailored specifically to their needs and interests, they would spend more time and money on the dispute). Negotiators can point out the unique advantages of each proposal that will be lost if it is not accepted (e.g., the party would not get the prompt payment of some of the money owed or would not have the benefit of a confidentiality provision in the agreement).

The principle of consistency. People have a strong desire to be consistent with their previous opinions, assertions, and actions. Consistency can be used quite effectively when setting rules for people to follow. The key is to prompt them to make an initial public commitment that is consistent with the rule. Written commitments to a desired form of action are particularly effective in this regard, especially when the written commitment is then shown to others. In one study, participants were somewhat more likely to stay loyal to their initial decisions if they wrote down the decisions privately. But they were far more likely to remain loyal to those decisions if they wrote them down and then showed them to others. In general, research indicates that individuals are likely to live up to commitments that are active, public, and voluntary.

The principle of reciprocity. People give back what another has given them. Although reciprocity is usually thought of as governing the exchange of money, goods, or services, it does not apply only to the material or monetary. When participating in a conversation or discussion, by providing others with attention, information, concessions, and respect, you will likely receive the same from them in return.

The principle of social proof. One fundamental way that individuals decide what they should do in a situation is to look at what similar people have done. Hence, the "proof" of what is correct isn't grounded in the physical environment but in the social environment: "If a lot of people like me are doing it, it must be the right thing to do." This tendency to look to and follow the lead of similar others will be strongest in situations characterized by uncertainty. For instance, have you noticed how frequently we look to our colleagues and coworkers to determine how we should behave in a new setting? To the extent that these individuals demonstrate effective skills, techniques, or other productive behaviors, we are likely to do so too.

Using the principles wisely. Although the six principles can be treated separately, they should not be employed separately. They are best applied in combinations and strings that multiply their impact. Effective practitioners will be aware of influence opportunities that allow the principles to be employed conjointly or sequentially. Also, the science of social influence can be commissioned for good or ill. One needs to understand the acceptable versus the objectionable use of the process. Just because we can employ the lessons of that science to influence others doesn't mean that we are entitled, or even wise, to do so. Using these principles to trick or trap others into assent has significant ethical and practical downsides. As the best influence professionals have long realized, to the extent that dishonest or high-pressure tactics work at all, they work only in the short run. Their long-term effects are malignant—undermining trust and damaging the reputation of the practitioner who employs them. Yet the same principles, if engaged appropriately, can influence decisions in a positive way. When the similarities are authentic, the windows of opportunity truly closing, the authority legitimate, the commitments freely made, the obligations genuine, and the social proof real, the resultant choices are likely to benefit everyone.

- This article is an abridged and edited version of one that originally appeared on page 20 of Dispute Resolution, Fall 2002 (9:1).
- For more information or to obtain a copy of the periodical in which the full article appears, please call the ABA Service Center at 800/285-2221.
- Website: www.abanet.org/dispute/.
- Periodicals: Dispute Resolution, quarterly magazine; Just Resolutions, quarterly newsletter.

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