He also conducted experimental studies to prove their effectiveness.
He has now shared these principles with audiences and readers around the world as a highly sought-after speaker, popular media source and best-selling author.
His book which has been a bestseller for over 25 years is called "Influence-the psychology of persuasion" and I highly recommend you read it.
In his research Robert Cialdini discovered six key principles of persuasion.
Authority: People will defer to experts.
When advertisers say, "Four out of five doctors recommend this product," they are relying on the authority of medical professionals to influence consumers.
Consistency: People will uphold their stated commitments.
After signing a petition in support of a social cause, for instance, people are more likely to donate to that cause later when asked. Individuals feel obligated to back up a public statement of support.
Liking: People like those who like them.
A good example is the ever popular Tupperware party. People are more likely to buy products from a friend than from a stranger.
Reciprocity: People will repay favours.
For instance, when the Disabled American Veterans began sending free mailing labels with their fund-raising letters, the response rate nearly doubled, from 18 to 35 per cent. People feel obligated to reciprocate when they receive a gift or favour, even when it is unsolicited.
Scarcity: People want things that are rare or scarce.
Social Proof: People follow the lead of their peers.
Let's take a quick look at one of these principles.
The Principle of Scarcity:
Items and opportunities become more attractive as they become less available.
This often holds true even when those items or opportunities aren't desirable on their own. Here are two examples that illustrate this.
Example One:
A consumer test provides insight into how the scarcity principle works.
Study participants were given a jar of chocolate chip cookies to taste and rate.
Some of them received 10 cookies in a jar; others received a jar that contained only two cookies. All the cookies came from the same box in the back room, but people who got only two cookies rated them as more attractive and able to command a higher price at the store than did people who received an abundant supply of the identical cookies (even though they did not rate them as tastier).
For these cookie-consuming critics, fewer meant better, even when taste was rated equivalently.
Example two:
Undergraduates at Florida State University, like most college students, rated their cafeteria food as unsatisfactory. Researchers found these opinions changed dramatically just nine days later, however, when they rated their cafeteria food as significantly more desirable than before.
Why?
Before rating their cafeteria food the second time, students learned a portion of the cafeteria had burned and that they would not be able to obtain meals there for several weeks. The cafeteria food was regarded as more desirable the moment that students realised it was less available.
I recommend you think about how you could use some of these six principles of persuasion in your own marketing.
"Persuasion is better than force" - Proverb
Action Exercise:
Look at your own products or services and see how you can apply scarcity in some way.
You might for instance have a deluxe version of your product or service that is available for a limited time only. Or perhaps for a limited number of people.
You may also like to read the book 'Yes!: 50 Scientifically Proven Ways to Be Persuasive' which has 50 ways to positively use these principles of persuasion in your business.
Graham McGregor is a consultant specialising in memorable marketing. You can download his 396 page 'Unfair Business Advantage' Ebook at no charge here. 
