Influence · Robert Cialdini

The six principles of influence

Why people say yes at the moments that decide a sign-up or a purchase: six shortcuts, plus the two lenses behind them, click, whirr and contrast.

106 techniques in the libraryVerified October 24, 2026

Most decisions are made fast, on one or two cues. Influence describes six shortcuts people rely on when they decide that way. We use them at decision points: the landing page, the sign-up, the paywall, the checkout.

We follow the revised edition, which has six principles. Each technique in our library names the principle it uses, so you can see its evidence grade before you try it.

Evidence grades across the 106 techniques in our library that map to this framework:

six shortcuts behind most yeses

In plain English

Robert Cialdini's Influence (revised edition) groups the tactics he observed into six principles: reciprocation, commitment and consistency, social proof, liking, authority and scarcity. Each is a usually reliable shortcut set off by a few cues, and contrast amplifies all six. Here they govern the decision points: sign-up, permission, upgrade, checkout, renewal, referral.

Cialdini spent years in the lab and about three years inside sales, fundraising and advertising training programs, then sorted the tactics he saw into six principles (Introduction, pp.v-vii). Each principle is a shortcut that usually points to a good decision, which is why people rely on it and why anyone who knows its cue can borrow it (Ch.1, pp.7-9).

Principle	The shortcut	Strongest when	Where
Reciprocation	Repay what was given first	The gift or concession comes first, even unasked	Ch.2, pp.13-42
Commitment and consistency	Stay consistent with a prior stand	The stand is active, public, effortful and freely chosen	Ch.3, pp.43-86
Social proof	If others do it, it is probably right	People are uncertain and the others are similar	Ch.4, pp.87-125
Liking	Say yes to people we like	The ask comes through a friend or after a pleasant moment	Ch.5, pp.126-156
Authority	Defer to legitimate expertise	The expert is real and relevant to the question	Ch.6, pp.157-177
Scarcity	Less available seems more valuable	It is newly scarce, and scarce because of demand	Ch.7, pp.178-203

Contrast is not a principle of its own but an amplifier: what comes second looks more different from the first than it is (see in-contrast-principle). Click, whirr is the model underneath: one cue sets off a stored response (see in-click-whirr). This is the revised edition, which has six principles.

How the knowledge base uses it [S]. Each decision point gets a coverage score per principle: 0 absent, 1 generic, 2 specific and placed at the moment of uncertainty, 3 all of that plus the right sequence and contrast and an identified deciding cue. Technique entries carry the principle they rely on and the decision points they fit.

Evidence. The principles rest on lab and field studies from the 1960s to the early 1990s and on the author's field observation. Treat book numbers as headline effects from single studies, not forecasts; several are much smaller in later meta-analyses.

The full entry: Influence: the six principles

Before the principles

Two lenses behind the principles

Framework · Influence
Click, whirr: automatic responding
single-cue decisions
Cialdini's core model: in a recurring situation, one trigger feature starts a stored response that runs without evaluation. It usually works because the feature normally comes with the real thing, and it misfires when the feature appears without it. People lean on it most when rushed, uncertain, distracted or new to a domain.
Framework · Influence
The contrast principle
order changes perceived size
The second of two things looks further from the first than it actually is. Contrast amplifies every principle: an expensive item first makes the next look modest, and a large refused request makes the next look small. It is nearly invisible to the people it affects, and intuition often predicts the wrong order.

Influence

The six principles

Each principle in plain English, with the techniques in our library that apply it.

01
Reciprocation
People feel they should return what they were given first.
People feel obliged to repay what others give them first: favors, gifts, information and concessions. It holds even for givers people dislike and for gifts nobody asked for, and small gifts can bring much larger returns. It has two routes: a favor before the ask, and a concession before the ask.
Evidence grades across 18 techniques: 5 grade B (moderate), 5 grade C (limited), 8 grade D (practitioner).
18 techniques, strongest evidence first
Show 14 more techniquesShow fewer
02
Commitment and consistency
Once people take a stand, they tend to act in line with it.
Once people take a stand, by word or deed, they feel inner and social pressure to act consistently with it, and they generate new reasons for it. Commitments change self-image most when they are active, public, effortful and, above all, freely chosen.
Evidence grades across 24 techniques: 11 grade B (moderate), 7 grade C (limited), 6 grade D (practitioner).
24 techniques, strongest evidence first
Show 20 more techniquesShow fewer
4 more techniques in the knowledge base
03
Social proof
When unsure, people look at what similar others do.
People work out what is right partly by watching what others do, and the more people, the stronger the cue. Social proof is strongest under uncertainty and when the others are similar; it is weakest, and most often wrong, when crowds are following each other rather than information.
Evidence grades across 17 techniques: 8 grade B (moderate), 3 grade C (limited), 6 grade D (practitioner).
17 techniques, strongest evidence first
Show 13 more techniquesShow fewer
04
Liking
People say yes more easily to those they know and like.
People prefer to say yes to people they know and like. Besides existing friendship, the book names five sources of liking: physical attractiveness, similarity, compliments, contact and cooperation, and conditioning and association. Requests routed through a friend borrow the friendship.
Evidence grades across 10 techniques: 1 grade B (moderate), 8 grade C (limited), 1 grade D (practitioner).
10 techniques, strongest evidence first
Show 6 more techniquesShow fewer
05
Authority
People defer to credible experts and signals of expertise.
People defer to legitimate authority, often reacting to its symbols (titles, clothes, trappings) as strongly as to substance, and they underestimate how much it moves them. Credibility combines expertise and trustworthiness, and arguing against one's own interest is one of the strongest trust signals.
Evidence grades across 6 techniques: 2 grade B (moderate), 3 grade C (limited), 1 grade D (practitioner).
6 techniques, strongest evidence first
Show 2 more techniquesShow fewer
- Evidence grade C. Limited evidence: few or small studies.One consistent voice of guidanceconsistent instructions everywhere
- Evidence grade D. Practitioner framework or anecdote: plausible, untested.Trophy Shelves (GT#64)passive achievement display
06
Scarcity
Things seem more valuable when they are rare or about to go away.
The harder an opportunity is to get, the more people tend to value it, for two reasons: hard-to-get things are usually better, and losing access threatens a freedom (reactance). Scarcity is strongest when it is new and caused by demand. It raises wanting, not how good the thing actually is.
Evidence grades across 23 techniques: 5 grade B (moderate), 3 grade C (limited), 15 grade D (practitioner).
23 techniques, strongest evidence first
Show 19 more techniquesShow fewer
3 more techniques in the knowledge base

Limits

What we don’t claim

These caveats travel with the frameworks everywhere they appear, on this site and in every answer Gamify It gives in your AI assistant.

The Hook Model is a practical design tool, not a validated or complete theory of behavior.Hooked, Introduction
Octalysis is a practitioner framework built from observing games, not a validated scientific model.Actionable Gamification Ch.15, pp.399-400
Left Brain and Right Brain are a metaphor for extrinsic and intrinsic motivation, not a claim about neuroscience.Actionable Gamification Ch.13, pp.342-343
The threshold is a heuristic, not a measured cut-off.

Go deeper

More from the knowledge base

Framework · Influence
Sequential requests: foot-in-the-door, rejection-then-retreat, lowball
how a first ask changes the next
Three procedures in the book change the answer to a second request through what happened at the first: a small yes first (foot-in-the-door), a refused large request first (rejection-then-retreat), or a decision won on terms that then worsen (lowball). The first two have product-safe forms; the lowball is listed under Not now on revenue grounds.
Framework · Influence
Commitment Quality Score
how strong a commitment ask is
A synthesis scorecard [S] for any commitment a product asks for: active 0-2, public 0-2, effortful 0-2 and inner choice 0, 3 or 6, for a maximum of 12. Inner choice is weighted to equal the other three together. A score of 4 or less on the first core action marks a weak commitment ladder.

Sources

Influence · Robert Cialdini
Intro · Ch.1, p.8 · Ch.2, p.27 · Ch.2, p.28 · Ch.2, p.13 · Ch.3, p.43 · Ch.3, p.57 · Ch.3, p.74 · Ch.4, p.98 · Ch.4, p.104 · Ch.4, p.122 · Ch.4, p.88 · Ch.5, p.129 · Ch.5, p.153 · Ch.5, p.126 · Ch.6, p.157 · Ch.6, p.165 · Ch.6, p.172 · Ch.7, p.183 · Ch.7, p.184 · Ch.7, p.193 · Ch.1, p.2 · Ch.1, p.4 · Ch.1, p.9 · Ch.2, p.31 · Ch.3, p.55 · Ch.3, p.75 · Ch.3, p.70

Source IDs: INF-M-10INF-M-12INF-M-18INF-M-20INF-M-28INF-M-35INF-M-37INF-M-42INF-M-44INF-M-55INF-M-56INF-M-57INF-M-58INF-M-64INF-M-65INF-M-68INF-M-01INF-M-04INF-M-25INF-M-29INF-M-83

Book content is paraphrased, never quoted at length. Last verified October 24, 2026.

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