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Influence (Revised Edition) by Bob Cialdini

6 broad principles behind getting people to 'mindlessly' (without thinking) agree to your request (what Bob calls 'compliance'): consistency, reciprocation, social proof, authority, liking, and scarcity. Important unsaid rule = material self-interest: people want to get the most bang for the buck.

You can also think of these as heuristics for people who are time constrained etc.

Automatic Behaviors

  • Fixed Action Patterns/Blindly Mechanical Patterns of Action
    • Example: Mother turkeys respond to cheep cheep sound by young turkeys. Experiment by M. W. Fox: polecat is a natural enemy and turkeys will attack a puppet of it. but if a tape recorder in the puppet plays cheep cheep, turkeys will take it under care.
    • Photuris females flash mating signals of Photinus firefly to eat them (Lloyd 1965)
    • Difference between trigger and actual threat. Turkeys aren't responding to actual threats, they are responding to triggers.
    • Parallel form of automatic response in humans = people will be more likely to grant you a favor if you provide a reason. (Research by Ellen Langer.)
      • "Excuse me, I have 5 pages. May I use the Xerox machine?" (60% comply, which is also notable.)
      • "Excuse me, I have 5 pages. May I use the Xerox machine because I am in a rush?" (94% comply.)
      • "Excuse me, I have 5 pages. May I use the Xerox machine because I have to make some copies?" (93% comply.)
    • Another example: stereotype: expensive = better. Increasing price may increase sales. Ad by Dansk: 'Expensive by design.'
    • Related wisdom: 'civilization advances by extending the number of operations we can perform without thinking' (Alfred Whitehead)

Contrast Principle

  • If two items presented in order, and if second is different from first, second's absolute value on commensurate trait will seem larger:
    • If you pick a light object and then a heavy one, the weight of 2nd object seems heavier than when lifted first
    • Less satisfied with our looks because of looks of good looking people in media (Kenrick and Gutierres 1980, plus one w/ Goldberg)
      • People rated others less attractive if they saw ads in popular magazine first
      • Men in dorms rated looks of blind dates rated them lower if watching Charlie's angels
    • One hand in hot water, one in cold, then move both to lukewarm water. Hand moving from cold to lukewarm will register as warm, and hand moving from hot to lukewarm will send the signal that it is cold. Same pail of water, two different interpretations.
    • Application:
      • Clothiers sell expensive stuff first. If you have bought a suit for $495, a $95 sweater doesn't seem expensive.
        • Whitney, Hubin and Murphy --- avg. price of accessories greater is bought after the suit than before.
      • Real estate companies: setup properties or run down properties at inflated prices maintained by the company. Show those to customers first.
      • Automobile: sell the base car before talking about one option or another

Reciprocation + Contrast

  • If someone does a favor, you will feel obliged to return the favor
    • No human society that doesn't ascribe to the reciprocation rule (Alvin Gouldner)
    • Experiment by Dennis Regan:
      • Subject rates quality of painting. Confederate does a small favor for the subject (bring a coke --- I asked the experimenter if I could get a coke so I brought one for you also) half the time. Post-experiment, the confederate asks for a favor from the subject: buy some raffle tickets.
        • 2x tickets sold when the confederate does a favor.
        • How much subjects liked the confederate affected how many tickets they bought in control but not in favor condition.
        • Can cause unfair exchanges: coke = 10 cents. Raffle tickets = 25 cents. On average people bought 2 if given coke.
    • Applications:
      • Hare Krishna/Hare Rama: Give people a 'gift' (Gita/Back to Godhead/flower) to the passerby. Don't take it back.
      • Working for political donors can sometimes be an act of reciprocity, less about strategy
      • Free sample. Disabled Veterans org. reports simple mail appeal = 18%, if you include gummed, address labels etc. = 35%
  • Ask for something big, then smaller (what you originally wanted) (Calls it Rejection then Retreat strategy)
    • Boy sells $5 tickets, and then when you say no, suggests buying $1 candy:
      • Concession from him causes concession from you
      • Contrast principle also applies as the next demand is seen as more modest:
      • The more expansive demand is irrelevant information. But it changes your preferences.
    • Ask students to do a big pro-social thing and then asked for a smaller one. Compliance rate tripled.
    • Adding lines in the script that the censor is sure to ax so they they would negotiate what they wanted to include (Grant Tinker and Gary Marshall)
    • Liddy in Watergate had proposed more ambitious ideas before the break in idea was approved
    • Show customer the deluxe model first
    • Reject then retreat not only causes people to agree to the request but also more likely to carry it out.
    • Reject then retreat also works in behavioral games --- people walk away with more money.
      • People think that their resistance/tactics causing others to concede
      • People also walk away most satisfied when opponent conceded some ground
    • How to say no?
      • Not accept the initial gift
      • Think of initial gift as a sales device rather than a gift

Commitment and Consistency

  • Once a stand has been taken, there is pressure to be consistent
  • Evidence:
    • People more confident of a horse winning just after buying the ticket than just before it (Knox and Inkster 1968; see also Rosenfeld, Kennedy, and Giacalone 1986)
    • People will risk personal harm if they say yes. Experiment by Thomas Moriarty: Lay a blanket and radio next to people at a park. Leave. A confederate 'steals' the radio. Most bystanders do nothing. If the experimenter asks before leaving, hey can you watch out for these, 19 out of 20 people stop the 'thief'.
    • Steven Sherman: asked people to predict if they would volunteer for 3 hours. Many said yes. Tony Greenwald used the same technique to boost election turnout.
  • Applications
    • Toy manufacturers will advertise toy X a lot for the holidays but would undersupply the stores with it. Why? Parents will commit to buying toy X for their kids. But they won't be able to buy them the toy for the holiday, and would buy them instead toys Y and Z. Since post holidays, parents would still feel compelled to buy their kids toy X, they would go to the toy store and buy X. Increases total sales but boosts post holiday sales.
    • How are you doing? Experiment by Daniel Howard.
      • Standard solicitation (18%) versus "How are you doing?" (32%). How are you doing triggers 'I am doing great!' (108 of 120 people ) And then this is used to say "That is great to hear because I want to ask you if you would be willing to help make a donation to victims of this unfortunate ..."
      • 89% of people who agreed on phone did make a purchase.
    • Pallak:
      • information about fuel savings: no reduction in fuel usage
      • information + publicize in local newspaper that the family has agreed ---> reduction
      • but then information given that no publicity in newspaper but families still reduced. in some ways not having newspaper publicity allows people to 'own' their commitment (Cialdini).
  • Start out small and ...
    • Experiment by Freedman and Fraser
      • 17% --- Ask homeowners to put up a large public service sign
      • 76% --- Ask homeowners to put up a small public service sign in their yard. 2 weeks later ask them to put up a large public service sign.
    • How the Chinese ran the POW camps:
      • For instance, start by asking POWs to make mildly pro-Chinese or anti-US statements. Then ask them to explain how. They emphasized that people always write stuff down --- so that people changed their self-image etc. And then beam what POWs said to everyone. Now POWs branded as collaborators and then collaborated even more.
    • Use small commitments to change citizens to public servants, prospects to customers etc.
    • Low-ball offer: you get a great deal, commit, but later there is some error, revise upwards but you are still willing to buy
  • Public commitment more effective
    • Duetsch and Gerard: ask some students to commit publicly to their judgments of length of lines, some to commit privately, and some to not commit at all. when given new information, people who didn't commit at all were most open to change
    • Hung juries more common if opinions expressed with a visible show of hands
    • example of public commitment that helped someone quit smoking
  • Written commitments more effective
    • Amway people ask sales people to write sales target etc. on paper
    • Companies used to run 25-word, 50-word testimonial contests around 'Why I like ...'
  • Greater the effort, greater the pressure to be consistent
    • Hazing rituals in fraternities

Social Proof

  • "one means we use to determine what is correct is to find out what other people think is correct."
  • Examples
    • Laughter tracks (Smyth and Fuller 1972) --- people laugh more and longer when laughter track is there
      • Paris opera houses and people paid to applaud: claquers
    • Advertisers love to point out 'fastest growing', 'largest selling'
    • Charity telethons list people who have already contributed
    • Sorrows of Young Werther and Suicides --- David Phillips
    • Bandura (1967)
      • Dog phobia treatment
      • Show kids another person playing with a dog. Film clips work as well as live proof. And more kids shown playing with dogs, more convincing
      • after only four days, 67% of them were willing to climb into a playpen with a dog and remain confined there as everyone else left the room... continued effect when tested a month later
    • O'Connor channels Bandura in treatment for socially withdrawn children:
      • clip shows a shy kid who observes kids playing and then joins to everyone's pleasure
  • Most likely to look for social proof when we are most uncertain
  • Bystander effect can be looked at as an example of social proof:
    • Bibb Latane and Darley, Genovese case
      • How could 38 'good people' fail to act? Slow death.
      • Pluralistic Ignorance: If bystanders aren't doing something, maybe it is not that important
        • or maybe others have (conventional explanation)
    • What to do if you need help (and against bystander effect):
      • Be specific in request
      • Make the request to particular people
      • Social proof will eventually work for you as people see other people helping
  • Proof by people similar to you more persuasive
    • Lost wallet experiment: returned more often if person more similar than when not
    • Show kid of similar age who can swim without a ring --- convinces kid that he doesn't need a plastic tube to swim also
  • How to say no?
    • Pay attention to the fact that social proof is manufactured
    • We overestimate how many people are doing X, and evidence available to them


  • Happier to heed to requests of those we like
    • Classic example: tupperware party
  • Attractive people are more liked, rated more highly on talent, kindness, honesty, and intelligence
    • Canadian Voters: most voters don't realize the bias (Efran and Patterson 1976). See Gabe Lenz, Enos, etc. for better estimates than the 2.5x estimate given here.
    • Good grooming when interviewing led to more favorable decisions in simulated interview
    • Courts --- attractive defendants are less likely to get jail, more compensation
    • Adults view aggressive acts by good looking children as less naughty
  • Similar people are more liked
    • People dressed similarly
    • Have similar background and interests
  • Compliments
    • Tell people you like them. Car salesman sent cards with 'i like you'
  • Familiar is more liked
  • Sherif (Liking ~ groups, competition, cooperation)
    • Being arbitrarily split into groups causes liking and 'us vs. they'
    • Assigning names to groups (eagles, rangers) causes those feelings to increase
    • When competition added, hostility increased yet more
    • Joint pleasant events like movies don't do much
    • Cooperation -> more pleasant feels
    • Used in recently racially desegregated schools: Aronson et al. developed 'jigsaw classroom' where people had to work together to master the material
  • Like more things, more generous when in good mood
  • Why are people fanatical about sports teams?
    • "So we want our affiliated sports teams to win to prove our own superiority"
    • "that many more home-school shirts were worn if the football team had won its game on the prior Saturday"
    • "By showcasing the positive associations and burying the negative ones, we are trying to get observers to think more highly of us and to like us more."
    • want to bask more in reflected glory when we don't think +ve about ourselves
      • "If they were asked to describe the team defeat, only 17% used the pronoun "we" in so doing. If, however, they were asked to describe the win, 41% said "we.""
      • but people who well on general knowledge test were equally likely
  • Associate with what is liked/disliked
    • Pavlov
    • Beautiful women and cars:
      • "men who saw a new-car ad that included a seductive young woman model rated the car as faster, more appealing, more expensive-looking, and better designed" ... and when asked later didn't think women influenced judgment
    • The person who brings bad news (weather man) criticized. Shakespeare: "The nature of bad news infects the teller."
    • Lunch (+ve feels because of food):
      • Endorse more statements shown when eating (Gregory Razran)
      • "at the typical fund-raising dinner the speeches, the appeals for further contributions and heightened effort never come before the meal is served, only during or after"
  • How to say no
    • Recognize that you like someone more than you should, why you may like them, etc.
    • Focus on the facts and question under consideration


  • Milgram
    • Broad cross-section of people
    • Post 'experiment' assessment shows that the people are normal on psych. scales
      • When researcher and 'victim' switched scripts so that researcher was asking the 'teacher' to stop, the 'teacher' stopped.
      • When two researchers were assigned per 'teacher' and researchers disagreed, the 'teacher' stopped
  • Other evidence:
    • 12% error rate in hospitals (whatever that means). Apparently partly attributable to others not questioning judgment of attending physician (Mike Cohen and Neil Davis in Medication Errors: Causes and Prevention)
      • Put medication in R ear --> People put the med. in the anus
    • Study in which call made to nurse to give (problematic) medicine to a patient:
      • title randomized. when title was doctor, 95% did it.
    • Leonard Bickman's experiment:
      • randomize clothing: regular/security guard
        • ask people to comply with some odd request on the street: pick up a paper bag, stand on the other side etc.
        • that guy over there is overparked. give him a dime (42% versus 92%)
    • People in business suits/regular pants/shirt
      • 3.5x more people followed the jaywalker when jaywalker wore the business suit
    • Motorists wait longer to honk at expensive cars than cheaper cars (50% versus nearly 100% honking)
  • People in authority are seen as a bit taller
    • Experiment in which person introduced in class as x from Cambridge university where x = student, demonstrator, lecturer, professor. Professor 2.5 inch taller than student.
  • Trustworthiness
    • Show good faith by saying something that isn't in your interests. even something small
    • assure people of fair mindedness
  • How to say no?
    • Is the authority figure truly an expert in the domain?
    • How truthful can we expect the expert to be here?
      • truthfulness is cued by people saying that they are working against their interests. once you trust the person based on an inexpensive gesture, you can exploit that. for instance, a waiter who suggested a dish that was 50 cents less than what customer picked and then used the trust to exploit the customer.


  • "opportunities seem more valuable to us when their availability is limited"
  • If stock is running low on x, it also means x is popular. And that goes back to social proof. And social proof can capture stuff like that x is actually better.
  • Applications:
    • Sold out: See if a customer is looking intently at X, tell them that what they are looking at is the last one and that has been sold. Now that customers see X as more attractive, look in the backroom.
    • Deadline technique: "Exclusive, limited engagement ends soon"
    • Buy as many photos of child as possible as 'stocking limitations' cause them to destroy all stock in 24 hours.
  • Parental pressure and 'Romeo and Juliet effect'
  • Psychologists think some pretty pointless experiments are informative:
    • experiment = regular beef sales call, beef supply short in future, beef supply short in future and the info. that the supply will be short is also not well known
      • beef sales greatest in last, followed by 2nd, followed by 1st. This is thought to convey something interesting.
  • Scarce cookies rated more desirable (not tastier) than plentifully available cookies
    • a. Some told that cookies given away because of demand for cookies
    • b. Some told that cookies given away because researcher had made a mistake
    • c. Control. only given fewer cookies.
    • a > b > c

Loss aversion

​ (Kludged under scarcity but its own point.)

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