Graham King

Solvitas perambulum

Influence, by Robert Cialdini

As an Amazon reviews says, “arguably the best book ever on what is increasingly becoming the science of persuasion.”

If you want to understand why you felt compelled to give money to a Hare Krishna devotee, how car salesman or realtor’s work, and much more, you should read this.

It’s also a very easy and enjoyable read. These are my notes. They cover all the content in the book, but don’t link to research. In the book, most of the statements have links to research papers to back them up.

Get Influence: The Psychology of Persuasion from your local library, this has sold so many copies they are bound to have some.


We can process incoming information cognitively in one of two ways:

  • Controlled responding, which is subjecting information to a thorough analysis. This is when we think a problem through, research it, etc. We only do this if we have the desire and the ability. It is intellectually taxing and time consuming.

  • Use judgmental heuristics such as:

    • Price as surrogate for value. Applies particularly to items which are hard to value: Wine, jewelry, art, employee salaries, etc.
    • Trust experts. This is why pseudo-science books always have ‘PhD’ or ‘MD’ after the author’s name.
    • Because – we want reasons to do something, even bogus ones.

Contrast principle: Two different things presented together or sequentially will feel more different than they really are. Hence sell the expensive item first, as the other items will seem cheap after that. Good cop / bad cop is about creating a contrast between the two, to increase liking of the ‘good cop’.

A fixed action pattern is an automatic behavior pattern often triggered by a single item in the information. Also known as a heuristic.


A Hare Krishna devotee presses a flower or a copy of the Bhagavad-gītā into your hand (that happened to me), or a store gives you free samples, and you feel awkward about taking it for free. You end up giving money or buying something you don’t want. That’s the norm of reciprocity at work.

We also reciprocate to concessions. Start witha large but not unreasonable request, which gets rejected, then ‘retreat’ to the target request. People who comply after this technique has been used on them feel more satisfied with their decision than those who agree straight away, because they ‘bargained’ for it. They shaped the outcome, so they feel ownership for it.

A recent research article I read (apologies, can’t locate link right now) supports this, by saying that when the seller of a product is the first to quote a price (typically quite high), the product sells for more than when the buyer opens the negotiation (with typically a low price).

Surprise increase the likelihood of the target using heuristics instead of controlled responding. A shaved headed person in orange robes shoving an ancient Indian text at you, that’s surprising.

Consistency / Commitments

We wish to think of ourselves, and appear to others, as being consistent in our behavior, we apply the consistency principle heuristic. We make up reasons to justify our behavior, to seem logical and in line with our previous behaviors.

Foot in the door technique: Start small and build. Extract a small inconsequential commitment, then a slightly bigger one, and so on.

Commitments are most effective when they are:

  • Public: Forces us to stick to it to look consistent. Especially effective for those whith lots of pride or public self-consciousness.
  • Active: Perform some action to take the commitment, such as writing, swearing an oath (also public), etc.
  • Effort-full: The bigger the price the bigger the commitment. Hazing / initiation ceremonies. Extract a bigger effort with foor-in-the-door technique.
  • Freely chosen:Avoid threats, or any external reward such as prizes. The commitment must feel freely chosen for the person to accept responsibility for it, it must feel internally motivated.

Caveat: If the commitment alone gets the same result as the goal, we may not pursue the goal. For example if you are going to attend law school so that people will think you are clever, and telling people you are going to attend gets the response and recognition desired, the motivation to actually attend is removed.

Commitments get internally justified, they grow their own legs. Car salesman will often low ball you, offer an artificially low price. You gladly accept the low price. Time passes as you fill in some forms, test drive, etc. They take the paperwork to their manager for final approval. Manager comes out and explains the salesman made a mistake, the price is higher. You would of refused the higher price originally, but now you are committed, and much more likely to accept the high price.

Social Proof

The greater the number of people who find any idea correct, the more a given individual will perceive the idea to be correct. This is the Social Proof heuristic.

We look to others for behavioral guidance when we are unsure, in an unclear, unfamiliar, or ambiguous situation. Often in such situations others do the same thing, which leads to pluralistic ignorance.

In an unclear emergency situation, a lone bystander will help, but a group looks to each other to decide how to act, and does nothing. This is the Bystander effect.

In an emergency situation you need to reduce the uncertainty experienced by bystanders:

  • Pick one and speak directly to him
  • Say you need help
  • Tell him how to help (“Call an ambulance”, “Help me out of my car”, etc)

Social proof is strongest when the others we look to for guidance are similar to ourselves. Hence Joe Average in television adverts.

Individuals in psychological pain look to others in similar situations to see how to deal with it. After a widely reported high-profile suicide, suicides increase, often using a similar method. Copycat crimes work in a similar fashion.

Books, products, feature One Million Sold or New York Times Bestseller on the packaging. Informing someone that many people like him (NY Times readers) have adopted a certain behavior makes them more likely to also adopt that behavior. Testimonials.


We prefer to buy from people we like. The strength of the social bond is twice as likely to determine product purchase as is preference for the product itself.

So, what makes us like people?

Physical attractiveness

More attractive people, all other things being equal, are:

  • paid higher salaries
  • less likely to be sent to jail
  • more likely to be helped in an emergency
  • more persuasive
  • seen as possessing more of the desirable personality traits
  • seen as having higher intellectual capacity

It’s pretty shocking, I know, but the evidence is plentiful.

Physical attractiveness triggers the Halo Effect, where one positive characteristic dominates the way that person is viewed by others.


We like people like us, whether that ‘like us’ is because they share opinions, personality traits, background, or lifestyle. To influence, try and match the target in as many ways as possible:

  • Dress
  • Interests
  • Background
  • Age, religion, politics, specific habits
  • Posture, verbal style, mood, etc. See Mirroring.


People want to be liked. Be nice, pay compliments, send a greeting card. There is evidence that positive comments make the giver more likable even when the receiver knows the compliment is not genuine.

Contact and co-operation

Positive familiarity. Familiarity caused by contact leads to liking, unless the contact occurs under unpleasant circumstances.

Here is a recipe for creating cross-group hatred: Split people into two groups. Name each one, to increase group identity (creating a minimum group). Wait. Then mix the two groups in competitive actions.

And here’s how to fix it: Successful joint ventures towards common goals.


An innocent association with good or bad things will influence the way people think about that us

  • Showing a credit card logo to people with positive associations to credit cards (most people) made them tip more, even when paying cash.
  • Killing the messenger: An association with bad news, used to be bad news for the messenger.
  • Celebrity endorsments. Sponsorship of the Olympics, or whatever cultural event is popular, even if the connection doesn’t make sense.
  • Stand attractive people by your product. Their beauty somehow ‘rubs off’ to make your product more appealing.
  • Hometown team victory makes us feel good, even though we obviously had no part in the victory.
  • Reductio ad Hitlerum: “Hitler was a vegetarian, so vegetarianism is wrong.”

Taken to extremes this is a personality flaw, showing low self worth, exhibited by groupies, sports fans, etc.


We trust experts, we obey experts. Often the appearance (symbols) of authority are enough, symbols such as:

  • Titles: PhD, M.D., Dr., Professor.
  • Clothes: Medicine is advertised on TV by actors in white lab coats.
  • Trappings: Car, house, ‘lifestyle’.

The seminal research on obedience to authority, and probably the most famous study in social psychology, is the Stanley Milgram experiment.


Opportunities seem more valuable when they are less available. Scarcity heuristic applies to information and goods.

If something is in short supply, everyone else must of wanted it, so it must be good. If something is in short supply, we are about to lose the freedom of acquiring it.

Reactance theory says that an attempt to restrict something makes us want it more, and hence assume it is more valuable and desirable than we previously thought.

Things that recently became scarce are perceived as more valuable than things that have been scarce a long time. We react to a freedom being taken away.

Competition for a scarce item increases perceived value of the item, beyond scarcity alone, or social proof alone. Hence: Auctions.