I recently got around to reading an influential book on …well, influence. Originally published in 1984, Robert Cialdini’s Influence: The Psychology of Persuasion (reprinted in 2007 by Collins) presents six ways that sales people and other “consent professionals” use commonly held mental models to get us to say “yes.” These aren’t highbrow mental models we’ve painstakingly constructed over the years regarding how our organizations work. These are basic, operational mental models that we learn at an early age, are reinforced every day, and help us get through our lives by streamlining the myriad of decisions we must make despite having incomplete information. These decisions range from the trivial— which toothpaste to buy—to major— which home to purchase.

Each of the six principles has an underlying mechanism that amounts to an automated response to a given stimulus. In most cases, this apparatus guides us to making a sound choice. But sometimes, especially when someone such as a sales professional is facilitating the choice, our mental models and associated decision processes can be used against us.

Six Principles

Cialdini provides full descriptions and terrific examples of each principle, which are only highlighted here.

Reciprocation. When someone does us a favor, we are strongly inclined to repay his or her kindness. Most people will go to great lengths to avoid being indebted to someone out of fear of being labeled a mooch or deadbeat. As experiments show, this desire to remain in good social standing is so strong that the dollar value of the repayment can easily exceed the value of the initial favor several fold.

Having established a mental image of ourselves, we will go to great lengths to preserve it.

Commitment and Consistency. Have you ever been surveyed by a stranger about your preferences or lifestyle, only to have it turn out to be a sales pitch? The author describes an instance in which a pretty young woman knocked on his door and asked if he would be willing to take a survey. She asked him about his dining and entertaining out activities. Wanting to impress her, he embellished the representation of his true social life—only to have her turn this image against him and point out that such a manabout-town would surely be interested in the entertainment discount plan she was selling. Like many sales professionals, she knew that we have a strong desire to maintain consistency in our mental models. Having established a mental image of ourselves, we will go to great lengths to preserve it. Whenever a car salesperson has you sit in a car and then describes how well the car suits you, he or she is tapping into the same desire for consistency.

Social Proof. What other people like me think is good, must be good. Most of the time, this is a handy shortcut in decision making—it’s usually true. But there are times when this herd instinct leads us astray. What parent hasn’t at least once reprimanded a child with the words, “If everyone else jumped off a bridge, would you?” Alas, there are examples that show that the answer is sometimes a resounding “Yes!” Cialdini cites the potent example of the People’s Temple in Jonestown, Guyana, where hundreds of followers calmly and voluntarily drank a lethal dose of poisoned punch. Once the most zealous of the group started things off, the rest, stuck in the middle of the South American jungle, looked to each other for guidance and were trapped by the social proof that this course of action was acceptable.

Marketers exploit this deep-seated mental model by playing up the popularity of their brand. The author supports legitimate appeals to this principle, such as advertisements that state that thus-and-such is the “bestselling brand in America”—so long as they are true. But he rankles at the use of staged testimonials given by professional actors pretending to be just like you and me.

Liking. The heart of this principle is the simple notion that we are more likely to accede to someone we know and like. No surprise there. Cialdini points out that what is more surprising is that complete strangers use this principle to make you more likely to do what they want you to do. Some sales organizations tap into this principle by getting you to give them a referral, whether you bought anything from them or not. Then they can approach your friend with a cheerful, “Sally said you might be interested in hearing from me.”

Another way they do this is to find out personal details, then claim a connection: “You don’t say! My mother was born in Idaho.” Or, “Oh, I love cooking on the grill, too! Out there every weekend this time of year.” You may have just met the salesman 10 minutes ago, but he can’t be all bad, can he?

Authority. The author points out that we are raised to have an astounding deference to authority. Christians learn early that Adam and Eve were cast out of the Garden because they disobeyed The Authority. Abraham is revered for his devotion to God, even when asked to kill his son. In most cases, following the lead of authority figures is an easy short-cut to sound decision making. Authorities have more information or have spent time learning about an issue.

Marketers and con artists both tap into this mental model to get you to act to their benefit. Marketers will present someone as an authority figure and have them pitch their product. A common practice is having actors portray physicians, either by putting them in lab coats or having them say that they went to medical school. But rarely is the person a real doctor—you have to spot the tell-tale disclaimer. Cialdini cites studies that show it doesn’t even matter if you know the person isn’t a real authority. Astoundingly, just having them present themselves as one is enough to cause us to give their message credence.

Scarcity. We want what we can’t have. The author describes numerous studies that show this to be empirically true and not just a pithy saying. In other words, experiments prove that the more scarce we think something is, the more we are willing to pay for it. What’s more, we’re willing to pay more for something that was once readily available but is now suddenly scarce than we are for something that has been scarce all along. (The item’s previous popularity is social proof that it is desirable!) So it is no surprise that any experienced salesperson will try to convince you that the thing you’re thinking about purchasing is almost out of stock, on sale for a limited time, or otherwise scarce.

Polishing Our Lenses

It should be noted, though not at all surprising to readers of The Systems Thinker, that these principles are often intertwined. The saleswoman who offers you a cold drink is tapping into both Reciprocation and Liking. However, the author underscores numerous occasions where social psychologists have devised rather ingenious experiments to isolate the effects of each principle. And each stands on its own merit.

As a reader, it is fascinating to think about how these common mental models manifest themselves in my own experience. They also have proven to be the basis for a set of exercises around polishing my “lens” on the world around me—each one providing a case study for practicing mental model awareness (noticing that a mental model has been triggered) and mastery (evaluating and revising them, as necessary).

Cialdini intends the 280 pages of Influence to be a toolbox, if not a call to arms, for consumers accustomed to being taken advantage of by salespeople. He synthesized the six principles based on 35 years of work as a psychologist exploring how “consent professionals” influence those from whom they are trying to gain consent. His research included the infiltration of car dealerships, home/personal network sales organizations, and restaurants in order to observe how these organizations presented information and moved people toward a purchase or other decision favorable to them.

For each principle, Cialdini gives multiple examples of how sales professionals use it to drive people toward a purchase decision. The author also provides at least one recommendation for avoiding the trap. All basically boil down to (1) recognizing as early as possible that a mental model has been triggered, and (2) using that recognition to tell yourself that just because said mental model has been triggered doesn’t mean that you have to make the “automatic” decision.

The author’s clear and easy writing makes it well suited for the lay audience. While this alone might make it worth adding to your reading list, I recommend it to my clients and students for another reason: Its insight into the discipline of mental models. It’s one thing to go into a meeting where you know mental models will be tossed about and skillfully manage them. It’s another thing entirely to catch yourself in the middle of an automatic response —for example, about to pay for the service agreement on a new TV that you know in your heart-of-hearts is a bad deal. That’s “black-belt” mastery of mental models. I’m still hoping to get there one day.

Greg Hennessy is a writer living in Albuquerque, New Mexico. He is a member of the Systems Thinking Collaborative and teaches Strategy in the MS program in Organizational Leadership and Ethics at St. Edward’s University in Austin, Texas.