Book Summary: Influence, The Psychology of Persuasion

Influence, The Psychology of Persuasion
By Robert B. Cialdini

The world is a complex place. Every day, we have to make many decisions. Do I donate to the man holding the tin can? Someone asks me for help at work. I try to get my mom to have lunch with me. If we had to weigh each decision carefully before making a choice, we would be paralyzed by analysis. Instead we rely on shortcuts to simplify our lives. These shortcuts work most of the time, but there are exceptions to the rules. People who understand these shortcuts can make use of them to trick us into making unwise decisions. This book is about the shortcuts we use.

1. Weapons of influence


Cialdini cites an interesting study. Someone stands behind another person in a queue to use the photocopy machine. He asks the person before him to go first, and he asks using either

“Excuse me, I have five pages. May I use the Xerox machine?” 60%
“Excuse me, I have five pages. May I use the Xerox machine because I’m in a rush” 94% compliance

The first question worked 60% of the time compared to the second question, which worked 94% of the time. Ok, People like to have a reason for what they do. Give them a reason and they’ll more likely comply with your request. More interestingly, another question was tried:

“Excuse me, I have five page. May I use the Xerox machine because I have to make some copies?”

Of course, the reason given doesn’t really give a good reason at all, but it still worked 93% of the time, just about as well as the second question. So the reason you give doesn’t even matter.

Contrast principle.

The constrast principle: An ugly woman who appears after a pretty woman appears uglier than she really is. In practice, a salesperson first sells you an expensive item, after which he tries to sell you the cheaper items. The cheaper items will appear cheaper than they really are, so that you will buy them more easily.

2. Reciprocation.

The practice of reciprocation came about because it is useful for society. A society with this practice has an advantage over others, because reciprocation encourages the exchange of goods, it allows for division of labour, which results in many experts and the efficiency that entails in the production of goods. This is more efficient than disparate independent individuals who try to provide for all their needs themselves. Cultures will tend to encourage reciprocation then by socialization.

In a study, two subjects, one of which is an accomplice, were supposed to rate some paintings. There were two conditions. For half of the subjects, the accomplice goes out and returns with two bottles of coke, one of which he offers to the subject. For the other half, the accomplice does not go out to get any coke. After this, the accomplice tries to sell raffle tickets to the subjects. Unsurprisingly, the subjects who received the coke bought twice as many tickets as the subjects who did not. The subjects were also asked how much they like the accomplice. Those who had accepted the coke, bought as many tickets whether or not they liked the accomplice.

The rule of reciprocity is so strong that it does not matter whether we like the giver. Once he has given something to us, we feel obliged to him and feel a need to repay him. No subject refused the coke when offered because it would have been awkward to refuse: The accomplice had spent his money, the soft drink was an appropriate favour, not too expensive, and he also had a coke himself (imagine if he gave one without having a coke himself), so that would have made it impolite to refuse the coke when offered. But receiving the coke creates a sense of obligation.

The accomplice has made all the free choices, he chose the favour, he chose the form of the return favour. The subjects can refuse to buy the raffle tickets, but that would have been very hard. It would have required them to go against cultural forces. The raffle tickets that they bought were also more expensive that the coke that was bought for them.

This is practiced often enough by groups who solicit for donations. Some groups use reciprocation by offering a “free gift” such as a flower, before asking for donations. The ploy still works and increases the donations significantly. We do not have to ask for what we receive in order to feel obligated to repay so long as we receive something.

Concerning the gift giving process in human societies: There is an obligation to give, to receive, and to repay.

Reciprocal concession

The rejection-the-retreat method involves making a large initial offer which is usually rejected. The requester than retreats to a smaller offer. Having made this concession, the other person will feel obliged to make a concession of his own. The only one available to him is to accept the smaller offer. For example, after listening to a 1.5 hour long insurance sales pitch from an agent who had called me saying that he had been introduced by a friend, I decided not to buy anything from him and said so flatly. He tried to convince me otherwise but I was adamant. Having not sold me anything, he asked instead if I could give the names and contact numbers of any friends who might be interested in buying insurance. I was very tempted to do so, but I ultimately decided not to. Now I know what was at work, I felt obliged to reciprocate the concession he had made me.

The trick is to decide on a large enough initial request, which is later reduced to a smaller position. Too large an initial request will be seen to be unreasonable, so finesse must be used. A Gifted negotiator must have this in mind.

3. Commitment and consistency

People have an inclination to appear consistent. Consistency is associated with logic, rationality, stability, intellectual strength. We use consistency as a shortcut to help make decisions. Instead of weighing a decision, we merely have to be consistent with what we have done before.

When we want to deceive ourselves we can use consistency. For example, some researchers attended a presentation where the speakers were trying to sell a transcendental meditation course. They criticized the presentation and exposed the logical flaws in the presentation, questions which the presenters were unable to address. However, after the presentation, many people in the audience still went ahead to buy the course. They wanted to commit themselves to the course, so they bought it. For example, a student was desperate for help. He was failing his classes, did not have enough time to study, and was hoping that TM could help him. After hearing the questions that were asked, he knew that he would not sign up for the course if he went home to think about it. Therefore, he decided to sign up immediately to commit himself.

To activate consistency, force a commitment.

Experiment: Telephone ahead to ask someone how he would respond to spending three hours collecting money for American cancer society. Over the telephone, many people have no problems saying that they would do so. A few days later, an American cancer society representative actually called the same person to ask, who usually agreed.

Even the courtesy of replying to “How are you feeling this evening?” with “fine” is a commitment. This question was asked, after which the person was asked to donate some money to people who were not as fortunate as he is. Wanting to appear consistent to their reply, people are inclined to agree to the request. This approach produced 32% compliance versus the 18% compliance of the standard approach. To determine if it was the politeness of the question that resulted in greater compliance, another question was tried “I hope you are feeling well this evening” This approach produced 15% compliance.

Little by little

In the Korean war, the Chinese were very successful at getting American POWs to inform on one another in contrast to those in WWII. The Korean manipulated the prisoners’ self-image by using commitment and consistency pressures. First, they asked the prisoners to make mild statements, such as, “the US is not perfect.” Then, they were asked to indicate why the US is not perfect, and to write this down in a list. They were asked to read list in a discussion group with other prisoners. “After all, that’s what you believe isn’t it”. Then they were told to write an essay on this list. The Chinese then used his name and broadcast his essay to the entire camp. Now, other prisoners think that he is a collaborator. The man himself also realizes that he has written the essay without any strong coercion, and changes his image to become a “collaborator”. He now works more readily with the Chinese.

Commitment extends to other areas

People were asked to install a public service billboard at home which the words “Drive Carefully”. They were shown a picture of a very large billboard that obstructed the front of their home. (80% disagree) However, there was a particular sample where 80% of the residents agree to install the billboard. Weeks earlier they had been asked, and agreed to install a small 3 inch square sign to “Be a Safe Driver”. 80% of this sample agreed to install the billboard. Be wary of the commitments you make, even the small ones.

They extended the experiment, and asked people to sign a petition to “Keep California Beautiful”. 50% agreed to install the billboard, even though the petition had nothing to do with driving safely. The theory is that they had created in themselves an image of public-spiritedness. In keeping with this image, they agreed to install the billboard. Consistency can extend to other areas remotely connected to the commitment.


Writing things down is a time-tested method to effect commitment. It brings about internal (because we look at our actions to determine what kind of person we are) and external (because this written statement can be shown to other people) pressures to conform to this new image.

This principle is used in secret balloting, and in lucky draws which require us to describe why we like the product in a 100 words or less.


Written commitments also require more work than verbal ones. We value more the things we acquire with more effort than those that require less effort. Hence, hazing rituals in college. School bodies have attempted to replace hell week with help week, where participants take part in civic activities. This has not worked, although both can be equally unpleasant.

Inner choice and responsibility for our actions.

When people act after making a commitment, we want them to take responsibility for their actions. In the case of help week, the people can rationalize that they did so for charity instead of for joining the group. This weakens their commitment to the group. Without the element of charity, the only conclusion left is that they went through hazing in order to join the group. His previous act of joining then commits him to the group. Without taking inner responsibility for their actions, the students will not feel obliged to be consistent with their actions. Taking inner responsibility for our actions only occurs without the presence of strong outside pressure.

Experiment. There are 5 toys in a room. One of the toys is an attractive, expensive, battery controlled robot. A child is left alone in the room to play. The experimenter either provides a strong threat (“Do not play with the robot, if you do, I’ll be very angry and I’ll have to do something about it”) or a mild one (“It is wrong to play with the robot). In the first case and second case, 21/22 of the boys do not touch the robot. Six weeks later. The same boys are left in the room with the same toys. Of the first group 77% play with the robot, while in the second group, 33% play with the robot.

The boys in the second group took inner responsibility for their actions when the research left them alone with the robot. They thought to themselves that they didn’t want to play with the robot because they didn’t want to. The first group however attributed their actions to the researcher’s strong threat.

A reason should be strong enough to encourage the behavior, but not so strong that the person sees it as the obvious reason for the behavior, so that the person can take personal responsibility for behavior. Selecting just such a reason is not easy.

Inner change covers a wide range of situations. A public spirited man acts in a variety of public spirited ways.

Commitment is lasting. He will find new reasons consistent with his self image, so that when the original reason is taken away, he still behaves according to his new self image.

4. Social proof

Use the behavior of other people as a guide for one’s behavior.

Therefore: Bartenders salting the tip jars. Products in advertisements are “fast selling”.

Convenient shortcut to determine how to behave. When unsure of ourselves, most likely to look to others to determine how to behave.

This shortcut is used relied on especially when we are unsure of ourselves. This causes bystanders to do nothing when they come across someone who might need help. When it is not clear if someone needs help, we look to others to determine how to behave. Other people are probably doing the same. And we like to main an exterior of calm. So no one helps.

Only when emergency is clear is help very likely.

Solution: If you need help, speak directly to person. Be precise of need for help. You sir, in the blue jacket, call an ambulance. Leave no room for uncertainty.

Social proof operates better when we are observing people similar to us.

5. Liking

No surprise here. We are more agreeable to people we like. That tactic where the insurance person says that a friend of yours mentioned that you might want insurance. We feel obliged to the insurance agent because we might hurt out friend’s feelings if we reject the insurance salesperson.

People think that good looking people have more favourable traits, such as kindness, honesty, and intelligence. They are more persuasive, and are more frequently helped.

In real life, in actual criminal cases, in a study involving 70 male defendents, the good looking men were twice as likely to avoid jail.


We help people more similar to us. To appear more similar to a person, we mirror their body language. We see that a person has a book, and we say that we’ve read it too. Similarity breeds liking.

Contact and cooperation

The more familiar something is, the more we like it. In an experiment, faces were flashed quickly to the subjects, who could not recall the faces when asked to remember them later. However, they were more likely to like a person whose face had been shown more frequently when they met later. The effect then is unconscious.

More contact does not lead to liking though if the contact is unpleasant.

Use cooperation strategy to induce liking.

Conditioning and association.

We associate seductive the young woman in the advert with the qualities of the car being sold. Often, white house luncheons are held during which legislators are convinced of some poltical stand. In an experiment, political statements that were made while food was eaten gained in approval. This reaction was made unconsciously, as the subjects could not remember which statements had been made while they were eating.

Glory by association by identifying with a sports team. Low self worth can drive a person to seek worth outside of self. Therefore, parents who want their children to succeed.

6. Authority.

Milgram experiment

The learner memorizes pairs of words. The teacher gives the first word in a pair, and asks for the second word. He delivers increasingly strong electric shocks to the learner for each mistake made. The questions are delivered through an intercom system and the electric shocks are delivered remotely. As the learner answers wrongly, he starts to grunt, plead, and scream as the shocks get more painful.

2/3 of the subjects, acting as teachers, continued the experiment and delivered the shocks until the shocks were at their highest setting. The learner is actually an actor. The subjects looked to the researcher for instructions and when told to continue, ignored the learners pleas to stop. They went on, but were stressed. One person was twitching stuttering, pulled on his earlobe, said oh god let’s stop it. But he continued.

If the researcher told teacher to stop, while the learner told the teacher to continue, 100% of the subjects stopped.

The experiment demonstrates how we respect authority figures.

We obey authority because it confers an advantage on society. This a kind of evolutionary argument that I’ve been encountering in The Red Queen. Applied to human evolution, any genetic trait that does not increase the likelihood of a human passing down his genes via reproduction, gets left behind and is weeded out of the gene pool. By analogy, any trait in society that does not help it, gets removed as other societies with more beneficial traits trample over them. Obeying authority confers an advantage on society. It helps the creation of structures for economic production, trade, defence, basically, any social structure in society.

This deference to authority has been inculcated in us since we were young, when we listened to our parents and our teachers who were wiser and controlled our rewards and punishments. As we grew up to be adults, we listen to employers and government leaders, who have superior access to information and power. Listening to authority is a shortcut we use, we can let other people think for us.

Symbols of authority.

We do not have to be an actual authority figure to assume its power. We can simply use symbols of authority, such as titles, or clothes to create the illusion of authority.


A man was introduced alternately as a student, demonstrator, lecturer, senior lecturer, and professor professor. Each class estimated height. The greater his status, the greater his height.


A man was either dressed normally, or dressed in a security guard uniform. He asked people to do odd things, such as pick up litter. He achieved 40% compliance with the former vs 90% compliance with the security guard uniform.

7. Scarcity

Something is more valuable to us when it is limited. We infer that something is limited because more people want it, and that people want it because it is valuable.

Losing something is more motivating than gaining something of equal value. E.g to encourage women to check for breast cancer through self examinations. Word the advertisement in terms of health benefits lost rather than health benefits gained.

Psychological reactance

People react to losses in their freedom. Whether it is scarcity, or some restriction that occurs to make something less available, we respond to this loss of freedom by desiring this item even more.

Experiment: Two equally attractive toys, one beside a plexiglass barrier, and one is placed behind. 1 toy is placed behind a one foot tall barrier, the other toy, behind the two foot tall barrier. The 1 foot tall barrier can be reached over easily by the baby, while the two foot barrier has to be gone around if the baby wants to touch the toy. How quickly are the toys touched? The three year old babies went for the obstructed toy three times faster than the unobstructed ones.

This is a period of the baby’s lives when they discover they are individuals, and they begin to test the limits of their freedoms. The same thing happens with teenagers, who transition from children to adults.

Applied to censorship, we want information that has been censored more. Another finding is that we believe that censored information is more true.

Experiment: A woman was injured by a car. The jury was to award damages to the woman. When the defendant had no insurance, 33k was awarded, when he had insurance, 37k, when the judge ruled the evidence inadmissible, the damages amounted to 46k.

Newly experienced scarcity

Cookie raters either have a jar with 10 cookies, or with 2. They take one cookie, eat it, and rate it. The cookie from the jar with 2 cookies is more desirable. In another experiment, the ten cookie jar is replaced before their eyes with 2 cookies. The cookie is rated. This cookie is the most desirable of all.

We value most things which have become recently scarce.

Consider revolutions. Compare those who have traditionally experienced poor economic and political conditions (cookies all the time) with people who have been enjoying improving conditions, but have had their freedoms taken away (10 cookies reduced to 2 cookies). The second group is more likely to revolt.

Competition in addition to scarcity motivates us even more.

The jealousy plotline at work. Lovers invent a new admirer to increase their worth. Real estate agents invent a new potential buyer.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s