Watch the video below for an overview of the six principles of persuasion identified by researcher Robert Cialdini (pronounced chal-DEE-nee).

Cialdini’s 6 Principles of Persuasion

Social psychologist Robert Cialdini offers us six principles of persuasion that are powerful and effective no matter what the cultural context. Use them to help persuade people, but also recognize their use by others who may be leading you towards a decision or convincing you to adopt a particular perspective.

1. Reciprocity
2. Scarcity
3. Authority
4. Commitment and consistency
5. Consensus/Social proof
6. Liking

Principle of Reciprocity

I scratch your back; you scratch mine. Reciprocity means that when you give something to somebody, they feel obligated to give something back to you in return, even if only by saying “thank you.” If you are in customer service and go out of your way to meet the customer’s need, you are appealing to the principle of reciprocity with the knowledge that all but the most selfish among us perceive the need to reciprocate—in this case, by increasing the likelihood of making a purchase from you because you were especially helpful. Reciprocity builds trust and a relationship develops, reinforcing everything from personal to brand loyalty. By taking the lead and giving, you build in a moment a sense of obligation motivating the receiver to follow social norms and customs by giving back.

Principle of Scarcity

It’s universal to want what you can’t have. People are naturally attracted to the rare and exclusive. If they are convinced that they need to act now or it will disappear, they are motivated to act. Scarcity is the perception of dwindling supply of a limited and valuable product. For a sales representative, scarcity may be a key selling point—the particular car, theater tickets, or pair of shoes you are considering may be sold to someone else if you delay making a decision. By reminding customers not only of what they stand to gain but also of what they stand to lose, the sales rep increases their chances of swaying the customer from contemplation to action, which is to close the sale.

Principle of Authority

Notice how saying “According to researchers, . . .” makes whatever you say after these three words sound more true than if you began with “I think that . . . .” This is because you’re drawing on authority to build trust, which is central to any purchase decision. Who does a customer turn to? A salesperson may be part of the process, but an endorsement by an authority holds credibility that no one with a vested interest can ever attain. Knowledge of a product, field, trends in the field, and even research can make a salesperson more effective by the appeal to the principle of authority. It may seem like extra work to educate your customers, but you need to reveal your expertise to gain credibility. We can borrow a measure of credibility by relating what experts have indicated about a product, service, market, or trend, and our awareness of competing viewpoints allows us insight that is valuable to the customer. Reading the manual of a product is not sufficient to gain expertise—you have to do extra homework. The principle of authority involves referencing experts and expertise.

Principle of Commitment and Consistency

When you commit to something, you feel obligated to follow through on it. For instance, if you announce on social media that you’re going to do yoga every day for a month, you feel greater pressure to actually do so than if you resolved to do it without telling anyone. This is because written words hold a special power over us when it feels as though their mere existence makes what we’re doing “official.” If we were on the fence, seeing it now in writing motivates us to act on it and thereby honour our word by going through with the purchase. In sales, this could involve getting a customer to sign up for a store credit card or a rewards program.

Principle of Consensus/Social Proof

If you make purchase decisions based on what you see in online reviews, you’re proving how effective the principle of consensus can be. People trust first-person testimonials when making purchase decisions, especially if there are many of them and they’re unanimous in their endorsement. The herd mentality is a powerful force across humanity. If “everybody else” thinks this product is great, then it must be great. We are genetically programmed to trust our tribe in the absence more credible information, however, because it makes decision-making easier in the fight for survival.

Principle of Liking

We are more likely to buy something from someone we like, who likes us, who is attractive, and who we can identify with because we see enough points of similarity between ourselves. These perceptions offer a sense of safe belonging. If a salesperson says they’re going to cut you a deal because they like you, your response is to reciprocate that acceptance by going through with the deal. If you find them easy to look at—no matter which sex—you are predisposed to like them because, from an evolutionary standpoint, attractiveness suggests genetic superiority and hence authority. Furthermore, if the salesperson makes themselves relatable by saying that they had the same problem as you and this is what they did about it, you’re more likely to follow their advice because that bond produces the following argument in your mind: “This person and I are similar in that we share a common problem, they solved it expertly by doing X, and I can therefore solve the same problem in my life by doing X” (Business Communication for Success, 2015, 14.2).