Influence: The Psychology of Persuasion

Often cited as the reference when it comes to the psychology of persuasion, Influence: The Psychology of Persuasion is the first book I decided to review in my Pretend You Read It series, book review with actual quotes and summaries of the book’s most important parts, along with fun facts for dinner parties.

“Tape-activated Behavior”

A female turkey will take care of anything that does the cheep-cheep sound a chick does, and won’t take care and might even kill actual chicks that don’t do that cheep-cheep. This kind of behavior, although seemingly stupid at first, is actually very common in the human kingdom : as stupid as it may be for a mother turkey to take care of a stuffed animal producing a fake cheep-cheep sound, in nature this really simple action-reaction behavior is still good enough to ensure most mother will take good care of their chicks.

The same kind of action-reaction exists with humans as one. As an example, people with no specific knowledge of turquoise jewelry will take price as an indicator of value, assuming that high price equals high quality and value, because it most case it does. Humans, just like animals have many “tape-activated” behaviors, which in most case are flawed but still safely applicable and statistically viable, but they can be used to trick us into thought shortcuts such as high price = high quality which of course doesn’t always have to be true.


The rule says that we should try to repay, in kind, what another person has provided us.

In 1985, when Ethiopia was at its worst time in history, due to internal wars and famine, losing people on the battlefields, of diseases and starvation, the Ethiopian Red Cross decided to donate $5000 to Mexico City after it was hit by a major earthquake. What comes as an explanation for this rather unexpected behavior is the fact that in 1935, Mexico had sent aid to Ethiopia after the italian invasion, and despite the current famine and huge needs of the country, the desire to repay some kind of cultural and self-imposed debt was so important it made sense to donate the much needed money to repay what Mexico had given 50 years before.

During an experiment, a fake subjet may or may not do a favor for the real subject (bring him a soda), and then later ask the real subject to buy him raffle tickets. When the fake subject did a favor, subjects purchased twice as much tickets as when he didn’t do any favor. The force of reciprocation when it comes to persuasion is powerful into getting wanted behavior, without people realizing they’ve been influenced, due to the overwhelming cultural pressure, almost built into our thinking process. Whether or not we actually like the person doing us a favor doesn’t even seem to matter, the feeling of obligation to repay surpasses what we’d believe to be important.

The rule enforces uninvited debts

There is an obligation to give, an obligation to receive and an obligation to repay. It’s the obligation to receive that makes it so easy to exploit the obligation to repay.

When offered to buy tickets to a Boy Scout circus show for $5 dollar, the author explains how, when refusing she placed herself in a debt situation, and when a concession from the boyscout appeared, in the form of a second offer for $1 chocolate bar, the author felt the need to make a concession herself, and thus buying $2 worth of unwanted chocolate bars. As it turns out reciprocation doesn’t even require the offer to be taken, as a concession will trigger the same behavior, resulting in a higher chance of the second offer being accepted.

It is rather easy to exploit this fact, using the rejection-then-retreat technique : making an offer than will most likely be turned down, and then present the offer you want accepted as a concession after the refusal of the first one.

This tactic works because it also involves the contrast principle, which states that something appears less costly when it appears after a more expensive one, making, for example, men to purchase more costly accessories after they’ve bought a new suit than before.

Commitment and Consistency

The desire of consistency is a very strong drive that made betters, according to a Canadian study, to believe their horse had more chances of winning a race after placing their bet than before. They simply convinced themselves they had made the right decision and felt better about it.

Like most forms of automatic responding, consistency offers a shortcut through the density of modern life. Once we’ve made our mind about an issue, stubborn consistency allows us a very appealing luxury : we really don’t have to think hard about the issue anymore ! […] Instead, all we have to do when confronted with the issue is to turn on our consistency tape and, whirr, we just know what to believe, say or do.

Commitment on the other hand is what forces parent to make January and February sales go up for the Toy industry. Christmas is coming, kids want that awesome toy they saw on television and parents promise to get it for them. All the parents go shopping at the same time and toy manufacturer didn’t ship enough of that toy. The parents then proceed to buy something else for Christmas, of equal value of the toy they’d promised but couldn’t get. January comes, and the parent go back that toy they’d promised now that it’s available again. That sounds logical, you should keep your promise right ? Sure, but you ended up spending twice what you wanted on toys, plus buy at a period that doesn’t seem so good for sales. Brilliant right ?

Another way researchers managed to leverage the power of commitment was through a simple call to a bunch of people, asking them if, in case they were asked to, they would agree to volunteer to go door to door to collect donation to help cure cancer. To avoid seeming uncharitable to the interviewer and themselves, most subjects replied yes, without ever being asked to actually volunteer. But, when an actual person from the association came at their door and actually asked if they would volunteer, people whom at been called were 700% more likely to agree than people who hadn’t been called before.

The power of commitment comes from the ability to modify someone’s self-image, to later use that image of themselves to justify a behavior they might not have wanted before. The actions we take, however small they are are informations we use to make up our self-image and thus, getting a small action is a way to make someone go in the direction you want them to.

Social Proof

If you’re like me, if asked about laugh track on humorous shows, you would say they’re at best slightly annoying, or maybe even completely disgraceful. Yet they’re so popular in almost all funny TV shows, but why are they still there ? Because research shows people tend to rate as funnier and laugh more when a show has laugh tracks and when it doesn’t. It even turns out the impact on the rating is even better for the least funny jokes ! This, people is the power of social proof.

The rule states that we, as human beings, search for the correct thing to do in a confrontation at what other people think is the correct thing to do. When a lot of people are doing something, we interpret it as being the appropriate thing to do as well.

This behavior can be spotted in ads when a product is advertised as “fasted-growing” or “best seller”. You’re not told the product is good, you’re told many people thought it was, and if they did, you naturally think you should too.

A study involving children afraid of dogs involved the kids watching videos, 20 minutes a day of another child happily playing with a dog. Later, 67% of the children whom were before afraid of dogs would agree to play, pet dogs and even remain alone with them for a moment. Even more impressive, this behavior was a long term one, the fear disappearing more and more as time passed.

Another important factor of social proof is how close we are to whoever we’re supposed to be mimicking.

Well I’m three years old, and Tommy is three years old. And Tommy can swim without a ring, so that means I can too !”


As a rule, we most prefer to say yes to requests of people we know and like.

Although completely aware of the fact that a transaction is affected by the liking between the 2 parties, most people either don’t mind, or don’t know how to handle it properly, making it an easy way to abuse friends into buying stuff from you.

Even more impressive, it has been found that friends don’t even need to be present to ease a transaction, even just mentioning their names can higher the likelihood of compliance. Remember those Facebook widgets with pictures of your friend ? Well here’s how they persuade you to do what they want.

Good Cop/Bad Cop is another example of this way to influence people, where policemen start by introducing an opponent, the Bad Cop, so that the Good Cop later appears as a teammate instead of just a second cop, the suspect is now working with the Good Cop for a reduced sentence, confessing the crime for a shorter stay in prison, with the help of his buddy Good Cop.


The idea of potential loss plays a large role in human decision making.

This behavior is very often used when trying to sell something, playing on limited stock or time to order. Think of Amazon letting you know how long you have for that item to ship today for example. Offering something that will be unavailable later gives it more value in the eye of the prospect. Even just the idea, without certainty of unavailability makes it more important.

The “good” thing with this is that it can be used hand in hand with a technique discussed earlier for a devastating combo : say you want to buy a table. That one is great but damn, I’m not sure there’s any left in stock, people just love’em, they’re probably sold out. Social Proof and scarcity. You know what, I can check in the stock, but if there are any left, they’re probably hidden somewhere and hard to find, I can check for you but not if you aren’t really interested (making a concession for you, Reciprocity). I’ll go only if you tell me you’re buying it if I can find it. Most likely by now, you say yes, and because you want to be consistent with yourself, when I come back with said table, you simply buy it.


Influence: The Psychology of Persuasion is a great read with lots of anecdotes to make it easy to read, scientific research, surveys and all that. Doesn’t sound so surprising that I’m convinced all these techniques work and I can’t wait to figure out how to try and use them on my own marketing efforts.

I didn’t write about Authority, which is a chapter of the book I couldn’t really relate to. Although interesting (probably with the most disturbing experiment explained) and weird, I just couldn’t figure out how that would apply to my wanabe-marketer’s life. If you want to know more about it, you’ll just have to read the book. It’s rather short and easy to read too, with enough weird experiments and unexpected results inside to animate a whole party with fun facts.

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