Learn how to use the six principles of reciprocity, liking, social proof, authority, scarcity, and consistency to increase your influence.

Limited time offer! Most popular item! 4 out of 5 dentists recommend! If any of these phrases ever convinced you to buy something, you understand the power of influence and can use it to your advantage in your business and daily life.

You don’t need to attend any fancy sales courses or get your M.B.A. from Harvard in order to learn how to persuade people. In fact, you already know how to do it. You have been using the six most persuasive techniques your whole life.

So what are the six principles of persuasion and how can you use them more effectively?

Social psychologist Dr. Robert Cialdini explains each technique and how to apply it in his bestselling books Influence and Pre-Suasion.

The rule of reciprocity runs strong in all of us.

Reciprocation

Did someone ever pay for your dinner—and then ask for a favor? You probably felt a strong pull to say yes. Referred to by behavioral scientists as the rule for reciprocation, we all have a societal inclination to say yes to those people we owe.

It’s so powerful that Cialdini states in one study, shoppers at a candy store who received a free sample of chocolate upon entering were 42% more likely to purchase candy than those who did not receive a gift.

However, for reciprocity to be effective Cialdini states that a gift must be meaningful, unexpected, and customized. In one study on tipping at a restaurant in New Jersey, diners who received a piece of chocolate with their check increased their tips by 3.3%. But when diners were allowed to have 2 chocolates, the gift became more meaningful and the server’s tips increased by 14.1%.

The tip increased more when the second chocolate was unexpected. When the server left the customers after offering the first chocolate and then came back unexpectedly to the table to offer a second, the server’s tips increased by 21.3%.

The gift should also be customized to increase the reciprocity effect. In another restaurant study, when diners were given a gift of a keychain upon entry, Cialdini stated that spending increased by 12%. However, when diners were offered a customized gift of a food item—in this case yoghurt—their spending increased by 24%.

Liking

Flattery gets you everywhere. We all do things for people who we like (and who we believe like us). While you use the power of liking all the time with friends, how can you get someone to like you when you have just met?

Cialdini points out two techniques that can get people to like you right away: highlight similarities and provide compliments. You can highlight similarities by matching the other person’s tone or body language, or by finding common ground, such as shared interests or common hometown.

Compliments also work wonders. Especially from people we just met. In a study conducted at a hair salon on the effect of compliments on tipping, when stylists complemented customers with the phrase, “Any hairstyle would look good on you,” their tips rose by 37%.

Social Proof

Social proof is a powerful persuader. Did you ever notice when you are shopping online, say at Amazon.com or some other website, you look at the most popular items when deciding to make a purchase? If you have, you are using the principle of social proof to influence your choice.

Cialdini states that social proof offers us validity and feasibility for our decisions. Validity reduces our uncertainty when making a choice. If others have done something before us, it must be okay. In an observational learning study on restaurants, when the label “most popular” was attached to a certain dish, it increased sales of that dish by 13 to 20%.

Social proof also offers evidence of feasibility, that something can be done because others have done it before you. In a study on normative social influence and conserving energy, when the researchers stated that most of the neighbors do try to conserve energy, this idea increased energy savings 3.5 times more than other messages.

Authority

If 4 out of 5 dentists recommend a type of gum, then it must be okay, right? If the author has linked to a number of studies done by researchers, then the claims are true. So goes the principle of authority.

Cialdini explains that for someone to be an authority that person must possess expertise and trustworthiness. This is why you trust dentists, doctors, and researchers. People with degrees have expertise in a specific field.

Though you may not be a doctor, you also have expertise in your field or profession. The best way to gain authority is to be credentialed with a degree or through a testimonial. You can show this expertise with your resume, a degree on the wall, or by having a colleague give a testimonial and introduce you as an expert. Your colleague might say something like, “I’ll connect you with our expert agent in your area of interest.”

For trustworthiness, we want to know that the information we’re given is honest and impartial. One way you can gain trust quickly when giving information is by presenting a weakness and then explaining your strengths. This works in advertising, such as Buckley’s cough mixture in Canada where they said, “It tastes awful. And it works.”

Cialdini explains that a salesperson might set up trustworthiness by using a “however” phrase that explains a strength, “Our set-up costs are not the lowest; however, you’ll recoup them quickly due to our superior efficiencies.”

Scarcity

The simple fact is that people want what they can’t have. This explains why limited-time offers are so attractive to you. You are more afraid of losing something than excited to gain something. Scarcity also increases the value of an item.

For example, in a study where a grocery store limited the number of items that could be purchased by customers, stating only x item per customer, sales more than doubled for those items compared to similar items in the store that had no limitation.

You can use the same idea of scarcity when talking to people. Set a time limit for an offer. Create a certain number of products for sale. Remind people that they will lose money if they do not do something.

Consistency

Finally, we all want to be seen as consistent in our behavior. When you give a public commitment to a certain statement, idea, or action, you want to follow that commitment.

Reminding someone of their verbal commitment or having them give a verbal commitment to a statement is effective in increasing compliance.

Cialdini states that in a study done on how to increase the impact of reminder calls, a blood donor organization increased participation from 70% to 82.4% simply by changing their wording from “We’ll mark you on the list as coming then, thank you” to “We’ll mark you on the list as coming then, okay? [Pause for confirmation]. Thank you.”

Another way you can use consistency is when people call your company. Cialdini suggests that you ask the client, “Why did you call us?” Having this verbal commitment will set the stage for persuading them.

Use these six persuasive techniques in your life and business and you will see an increase in your influence.

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Kyle Crocco is an East Coast native and content creator for Big Speak. His career has taken him from authoring the Heroes, Inc. series, to living and teaching abroad in France and China, to completing his Ph.D. in Education at the University of California-Santa Barbara. He is also the lead singer for Duh Professors, a local Santa Barbara band.