Influence (review)

The intention of Cialdini with this book seems to be to defend against unethical use of persuasion techniques. However, it works as education as well.

As he tries to cover the whole field of persuasion techniques (called "compliance" in the scientific literature), he classifies it into 6 major groups: Consistency, reciprocation, social proof, authority, liking, and scarcity. Cialdini left self-interest out as it is obvious.

One overall theme is that human brains are lazy. This means we use shortcuts and heuristics all the time. Mostly this is great to be quick and energy-efficient but not always and one can take advantage of it.


One heuristic is that we want to stay consistent. Cialdini was interviewed by a beautiful girl how much he visited cultural events around the city. Trying to impress her, he exaggerated. Then she offered him a way to save money.

I remember quite well feeling my stomach tighten as I stammered my agreement. It was a clear call to my brain, "Hey, you're being taken here!" But I couldn't see a way out. I had been cornered by my own words. To decline her offer at that point would have meant facing a pair of distasteful alternatives: If I tried to back out by protesting that I was not actually the man-about-town I had claimed to be during the interview, I would come off a liar; but trying to refuse without that protest would make me come off a fool for not wanting to save twelve hundred dollars.

Sometimes humans abuse it to a ridiculous degree. On one occasion, Cialdini was at the show for a self-improvement program. During the presentation, a logician took the presenters apart and revealed that their arguments were bogus. Still, people signed up afterwards to pay for more.

Still thinking that the three must have signed up because they hadn't understood the points made by my logician friend, I began to question them about aspects of his argument. To my surprise, I found that they had understood his comments quite well; in fact, all too well. It was precisely the cogency of his argument that drove them to sign up for the program on the spot. The spokesman put it best: "Well, I wasn't going to put down any money tonight because I'm really quite broke right now; I was going to wait until the next meeting. But when your buddy started talking, I knew I'd better give them my money now, or I'd go home and start thinking about what he said and never sign up." [...]

In the form of my colleague, intrudes the voice of reason, showing the theory underlying their newfound solution to be unsound. Panic! [...] Here take this money. Whew, safe in the nick of time. No need to think about the issues any longer. The decision has been made, and from now on the consistency tape can be played whenever necessary.


Maybe the most simple principle is that we give back. If you give something the recipient feels obliged to reciprocate. The tricky thing is that the values can be off. For example, the Hare Krishna movement did gift people a cheap flower and then asked for a donation.

We even reciprocate for imaginary things. Cialdini tells that he once bought a chocolate bar from a boy scout although he doesn't like chocolate at all.

His request that I purchase some one-dollar chocolate bars had been put in the form of a concession on his part; it was presented as a retreat from his request that I buy some five-dollar tickets. If I were to live up to the dictates of the reciprocation rule, there had to be a concession on my part. As we have seen, there was such a concession: I changed from noncompliant to compliant when he changed from a larger to a smaller request, even though I was not really interested in either of the things he offered.

Social Proof

It seems reasonable that we look for social proof like reviews for things we intend to buy. However, this tendency becomes increasingly powerful the more uncertain a situation is. This leads to the bystander effect: If there are multiple people around and a situation is not obviously an emergency, people interpret the inactivity of the others that there is no need to help. Once the emergency is obvious the effect disappears though and Cialdini tell about a car accident where he got injured.

I remember thinking, "Oh no, it's happening just like the research says. They're all passing by!" I consider it fortunate that, as a social psychologist, I knew enough about the bystander studies to have that particular thought. [...] Pulling myself up so I could be seen clearly, I pointed at the driver of one car: "Call the police." To a second and a third driver, pointing directly each time: "Pull over, we need help." The responses of these people were instantaneous. They summoned a police car and ambulance immediately, they used their handkerchiefs to blot the blood from my face, they put a jacket under my head, they volunteered to serve as witnesses to the accident; one even offered to ride with me to the hospital.

On the other hand, if you increase the uncertainty the effect becomes stronger. Maybe even to the degree that hundreds of people kill themselves as it happened in Jonestown.

Most attempts to analyze the Jonestown incident focused too much on the personal qualities of Jim Jones. [...] No leader can hope to persuade, regularly and single-handedly, all the members of the group. A forceful leader can reasonably expect, however, to persuade some sizeable proportion of group members. Then the raw information that a substantial number of group members has been convinced can, by itself, convince the rest. Thus, the most influential leaders are those who know how to arrange group conditions to allow the principle of social proof to work maximally in their favor.

It is in this that Jones appears to have been inspired. His masterstroke was the decision to move the People's Temple community from its roots in urban San Francisco to the remoteness of equatorial South America, where the conditions of uncertainty and exclusive similarity would make the principle of social proof operate for him as perhaps nowhere else.


People following authorities like experts or officials is a good thing.

However, we underestimate its strength. Just wearing a suit instead of a shirt has a noticeable effect. Advertisements show fake doctors for more authoritative statements. And to crank it up, consider the Milgram experiment: People hurt others because a guy in a lab coat tells them to continue. That can happen unintentionally.

A physician ordered ear drops to be administered to the right ear of a patient suffering pain and infection there. But instead of writing out completely the location "right ear" on the prescription, the doctor abbreviated it so that the instructions read "place in R ear." Upon receiving the prescription the duty nurse promptly put the required number of ear drops into the patient's anus.

Obviously, rectal treatment of an earache made no sense. Yet neither the patient nor the nurse questioned it.

People rationalize the effect away. When activists intended to stop a train and lay on the tracks, the train did not stop because the operators followed authority. One activist lost his legs.

Mr. Willson, who served four years in Vietnam, does not blame either the crewmen or the corpsmen for his misfortune, he points his finger, instead, at a system that constrained their actions through the pressure to obey: "They were just doing what I did in 'Nam. They were following orders that are part of an insane policy. They're the fall guys." Although the crew members shared Mr. Willson's assessment of them as victims, they did not share his magnanimity. In what is perhaps the most remarkable aspect of the incident, the train crew filed suit against him, requesting punitive damages for the "humiliation, mental anguish, and physical stress" they suffered because he hadn't allowed them to carry out their orders without cutting off his legs.


Blatantly said ass-kissing works. It works even if the recipient knows it and if inaccurate.

The men in the study received comments about themselves from another person who needed a favor from them. Some of the men got only positive comments, some got only negative comments, and some got a mixture of good and bad. There were three interesting findings. First, the evaluator who provided only praise was liked best by the men. Second, this was the case even though the men fully realized that the flatterer stood to gain from their liking him. Finally, unlike the other types of comments, pure praise did not have to be accurate to work.

There is a double meaning. No only can people you like more easily persuade you but also people who are like you. A car dealer who claims to support the same sports team as you do is an example. Of course, you can combine it.

Remember Joe Girard, the world's "greatest car salesman," who says the secret of his success was getting customers to like him? He did something that, on the face of it, seems foolish and costly. Each month he sent every one of his more than thirteen thousand former customers a holiday greeting card containing a personal message. The holiday greeting changed form month to month (Happy New Year or Happy Thanksgiving, etc.), but the message printed on the face of the card never varied. It read, "I like you."


Rare things are desirable and to a degree just because they rare. If fewer cookies are available, people rate them as better for example. While cookies are harmless, the same effect applies for auctions where people are tempted to overbid each other to irrational degrees. Scarcity becomes more serious if certain freedoms become rare. People will fight for that.

The lesson applies as well to the politics of family as country. The parent who grants privileges or enforces rules erratically invites rebelliousness by unwittingly establishing freedoms for the child. The parent who only sometimes prohibits between-meal sweets may create for the child the freedom to have such snacks. At that point, enforcing the rule becomes a much more difficult and explosive matter because the child is no longer merely lacking a never-possessed right but is losing an established one. As we have seen in the case of political freedoms and (especially pertinent to the present discussion) chocolate-chip cookies, people see a thing as more desirable when it has recently become less available than when it has been scarce all along. We should not be surprised, then, when research shows that parents who enforce discipline inconsistently produce generally rebellious children.

Who should read the book?

The book is useful if you want to use the techniques intentionally. In marketing, sales, or as influencer, this is your job after all. If that is ethical behavior is a different question though.

You can also read the book for self-defense. It contains tips, how you may avoid to become a victim of the effects.

The book may also shape your idea of man in general. People believe they are more rational than they are. I find myself more tolerant. Many behaviors in the stories above can be considered "evil" but actually they are just human.

Humans rely on mental shortcuts and that is exploited.