The Psychology of Persuasion

By: Robert B. Cialdini

Published: 1984

Read: 2019


When we make decisions, for various reasons (lack of time, uncertainty, complexity, etc.), we rely on short-cuts: conditioned, automatic responses.

This book explores six mechanisms (reciprocation, consistency, social proof, liking, authority and scarcity) that reliably trigger automatic responses (short-cut behavior).

The six mechanisms are:

  • Adaptive: having automatic responses makes sense, because they are an efficient form of behaving and they work well most of the time.
  • Increasingly relevant: as environments become more complicated, we depend on an increasing amount of shortcuts to be able to quickly understand and act.
    • “Civilization advances by extending the number of operations we can perform without thinking about them.”
  • Easy to exploit: the downside to automatic behavior (reacting without thinking) is that it is easy to exploit people’s mechanistic responses to triggers.

Worth Reading:

This was a great book to listen to. It was published in 1984, but could easily have been written in 1924 – it has the same timeless, insightful and old school jocular tone as the books by Dale Carnegie and the sermons of Warren Buffett and Charlie Munger (this apparently is Munger’s favorite book).

The book is a helpful reminder that biases are not shameful shortcomings in human rationality, but helpful tools that generate “good enough” behavior most of the time. They are necessary short-cuts that help to simplify your daily life. Sure, in edge cases they may backfire, but mostly and often, they work.

Having said that, the six mechanisms highlighted can be helpful in assessing your own behavior and seeing where you are more likely to trip up and make mistakes (or be exploited).

Practical takeaways:

  • Reciprocate: when working in a group, return the favor.
    • Collaboration allows for division of labor, specialization and the pursuit of common goals.
    • Requires orientation to the future, sacrifices and trust.
  • Be consistent: unless the situation changes, stick to previous commitments.
    • Allows for stability, honesty, avoids over-thinking.
    • Make your commitments visible to help ensure consistent behavior.
  • Social proof: when a situation is unclear, look to the actions of others for information.
    • Lowers chance of dumb mistakes.
    • Look for people that are similar to you (shared goals, etc.).
  • Liking: associate with people you like.
  • Authority: hierarchy provides structure for cooperation and control.
    • Requires obedience, loyalty.
    • Needs to be backed by superior knowledge, judgement, truthful claims. 
  • Scarcity: the availability of a good provides information on its usefulness.
    • Scarcity restrains basic human need to be independent and have choices.
    • Creates desire for possession, especially increased scarcity (the loss of something that was available before).

Key concepts:

  1. Reciprocation
    • Pay back favors we have received.
    • Adaptive mechanism.
      • Evolved to help groups compromise, bridge gaps in interests and work together towards achieving common goals.
      • Allowed for socially beneficial interactions: division of labor, trade, development of group inter-dependencies, binding of individuals into efficient units.
    • Based on mutual obligations.
      • Fundamental principle: people operate on the basis that they have an obligation to give, to receive and to repay.
      • This extends to the obligation to make a concession when someone else makes a concession to us (for instance in negotiating).
    • Involves orientation to the future, sacrifice and trust:
      • Sacrifice: giving up something now.
      • Orientation toward the future: expectation of receiving something back.
      • Trust: knowing that you will not be exploited in the future lowers natural inhibitions against bartering.
    • A conditioned behavior:
      • Trained from childhood to comply with reciprocity.
      • Conditioned feelings of fairness and obligation are triggered.
        • Discomfort with being in a continued state of obligation (ie, wanting to repay debts to relieve yourself).
        • Threat of social sanctions.
  2. Consistency
    • Desire to be and appear consistent with previous behavior.
    • Adaptive mechanism.
      • Valued trait: consistency is associated with logic, intellectual strength, rationality, stability and honesty.
      • Efficient: consistency allows for effortless and efficient method for automatically (without over-thinking) dealing with complex environments.
    • Triggered by making a commitment.
      • Commitment is taking a stand that is visible to others: active, public, requires effort.
      • Changes a person’s self-image and creates pressure to comply with others’ perceptions.
    • Inner choice.
      • Commitment is stronger and longer lasting if a commitment is made in the absence of strong outside pressures.
      • A large reward (or threat) may trigger an immediate commitment, but is unlikely to result in a person taking responsibility for the commitment. It is unlikely to last.
    • Justification.
      • A commitment builds its own support system.
      • Motivated reasoning: generate new, additional reasons to justify initial commitment.
  3. Social proof
    • Behavior is more appropriate if other people are doing it
    • Adaptive mechanism:
      • Crowds provide valid and valuable information about how to act, you make less mistakes by acting in accord with social evidence than contrary to it.
      • More automatic behavior, lower need for personal investigation of each decision.
    • Uncertainty:
      • When a situation is unclear, most likely accept the actions of others as correct.
    • Similarity:
      • More inclined to follow the lead of people that are similar to you.
    • Pluralistic ignorance (everybody does the wrong thing):
      • In situations of uncertainty, you put your trust in the collective knowledge, assuming that others know more than you do.
      • But others are not acting on superior information and are themselves reacting to principle of social proof.
  4. Liking
    • Prefer to interact with people we know and like.
    • Triggered by:
      • Looks: using halo effect, one positive characteristic of a person dominates the way that person is viewed by others.
      • Similarity.
      • Compliments.
      • Common goals: triggers cooperative behavior.
      • Association with good attributes, success: triggered by need for prestige.
  5. Authority
    • Action motivated by obedience to hierarchy structure.
    • Adaptive mechanism:
      • Hierarchy provides structure for cooperation and control.
      • Obedience, submission, loyalty to recognized authority allows for short-cuts, automatic behavior.
    • Assumption of superior knowledge, judgment within hierarchy.
    • Evidence of authority.
      • Triggered by credentials (status, title, size, etc.) or (truthful) claims.
  6. Scarcity
    • When freedom to have something is limited, a person experiences an increased desire for it.
    • Adaptive mechanism:
      • Assumption that things that are difficult to possess are typically better than those that are easy to possess.
      • Assumption that the availability of a good provides information on its usefulness.
    • Autonomy, freedom.
      • Basic human need for autonomy, control, freedom, volition, entitlement: to be an independent being with choices.
    • Scarcity triggers restriction of freedom.
      • As opportunities become less available, we lose freedoms.
      • The need to retain our freedoms makes scarce goods more desirable.
    • Increased scarcity is worse.
      • We value things more that have become less available to us than the things that have always been scarce.
      • Potential loss of something that we had access to before increases our desire to retain it.
    • Importance of competition.
      • Competition provides social proof that an item is good, which further increases our desire for a scarce good.
    • Justify increased desire.
      • In order to make sense of our increased desire for scarce items, we (then) assign positive attributes to them.
    • Aim is possession.
      • The joy of the pursuit of a scarce good is mostly derived from possessing it, not from experiencing its use / function.

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