Persuasion
The 7 principles of persuasion, and how to use them on a website
Robert Cialdini's principles of persuasion explain why people say yes: reciprocity, commitment and consistency, social proof, authority, liking, scarcity and unity. This guide explains each one with the research behind it, shows how it looks on a website, and draws the line between persuasion and manipulation.
Short answer
The principles of persuasion are seven mental shortcuts, identified by psychologist Robert Cialdini, that make people more likely to say yes: reciprocity, commitment and consistency, social proof, authority, liking, scarcity and unity. On a website, each one works honestly only when it rests on facts the customer would be glad to know.
- Each principle has an honest version built on true facts and a manipulative version to avoid.
- The most persuasive social proof comes from people like the visitor, in a situation like theirs.
- Scarcity is the principle most often faked, with countdown timers that reset and stock warnings that are always on.
- Regulators such as the US Federal Trade Commission now name the manipulative versions as dark patterns.
- AI agents do not feel social pressure, but they can read evidence, so every claim should be true and specific.
What are the principles of persuasion?
The principles of persuasion are seven mental shortcuts, identified by psychologist Robert Cialdini, that make people more likely to say yes: reciprocity, commitment and consistency, social proof, authority, liking, scarcity and unity. Each one usually helps people decide quickly and sensibly, which is also why each one can be misused.
Cialdini published the first six in 1984 in his book Influence: The Psychology of Persuasion, drawing on experiments and on years spent studying how salespeople, fundraisers and advertisers win agreement. He introduced unity, the seventh, in Pre-Suasion in 2016, and added it to the expanded edition of Influence in 2021. Influence is also on Convertica's list of the best CRO books.
In a 2004 review in the Annual Review of Psychology, Cialdini and Noah Goldstein grouped the forces behind these shortcuts under three basic goals: people want to see the world accurately, to build and keep good relationships, and to feel good about themselves. Every principle below serves at least one of those goals.
The 7 principles at a glance
Each principle has an honest version, built on facts the customer would be glad to know, and a manipulative version, built on things that are not true or that the customer would object to if they saw them clearly. The table shows both.
| Principle | Why it works | Honest website use | Manipulative use to avoid |
|---|---|---|---|
| Reciprocity | People want to return a favor | Free tools, useful guides, a free audit with no strings | A "gift" that quietly signs people up for something |
| Commitment and consistency | People like to act in line with earlier choices | Small, useful first steps before bigger ones | A first step that hides what comes next |
| Social proof | When unsure, people follow others | Real reviews, real customer counts, real "most popular" labels | Fake reviews or invented "12 people are viewing this" messages |
| Authority | People defer to credible experts | Named authors, real credentials, real certifications | Implied endorsements or badges you did not earn |
| Liking | People say yes to people they like and feel similar to | Real team photos, a human voice, shared values | Fake personas and stock "founders" |
| Scarcity | Things seem more valuable when they are limited | Real stock levels and real deadlines | Countdown timers that reset, false "only 2 left" |
| Unity | People favor those who share their identity | Speaking honestly to a community you belong to | Claiming an identity you do not share |
The principles of persuasion explained, with website examples
Each of the seven principles of persuasion below has a short definition, the research it rests on and examples of how it looks on a real website. Use them as questions for your own pages: where does this principle already work for you, and where is it missing or being faked?
1. Reciprocity
Reciprocity is the urge to give back when someone has given us something. In a 2002 study in the Journal of Applied Social Psychology, David Strohmetz and colleagues found that restaurant customers who received a small piece of chocolate with their bill tipped more than those who received none, and that tips varied with how much candy was given and how it was offered. The authors argued reciprocity explained the result better than mood or impression management.
On a website, reciprocity comes from giving something genuinely useful before asking: a free calculator, a thorough guide, a sample, a free audit. Convertica's free calculators and free CRO audit work this way. The gift has to be useful on its own. A "free" download that only exists to collect an email is not a gift, and people can tell.
2. Commitment and consistency
Commitment and consistency is the wish to act in line with what we have already said or done. Its best-known application is the foot-in-the-door technique: in Freedman and Fraser's 1966 experiments, people who agreed to a small request were far more likely to agree to a larger one later.
On a website, it looks like small first steps: a quiz before a recommendation, easy questions before contact details, saving an item before buying it, a free trial before a subscription. Each step should be worth taking even if the visitor goes no further.
3. Social proof
Social proof, which Cialdini also calls consensus, is the tendency to look at what others do when we are unsure what to do ourselves. In a 2008 hotel study in the Journal of Consumer Research, Noah Goldstein, Robert Cialdini and Vladas Griskevicius found that signs saying most guests reused their towels worked better than the usual environmental appeal, and worked best when they described guests who had stayed in the same room.
The lesson for websites is that the most persuasive proof comes from people like the visitor, in a situation like theirs: reviews from customers with the same problem, case studies from the same industry, "most popular" labels that are true. Convertica's case studies each state their metric, timeframe and source for that reason.
4. Authority
Authority is the tendency to follow credible experts. People defer to doctors, engineers and specialists because, most of the time, it is a sensible shortcut.
On a website, authority comes from named authors with real experience, real credentials and certifications, accurate data with sources, and recognition you actually received. It is undermined by vague claims of expertise with nothing behind them. This guide carries a named author for the same reason: you should be able to check who is telling you this.
5. Liking
Liking means we are more easily persuaded by people we like, and we tend to like people who are similar to us, who are friendly, and who are familiar. Familiarity grows with exposure, as the guide to the familiarity effect explains.
On a website, liking comes from real people and a human tone: team photos, a founder's voice, customer stories told in their own words, and support that sounds like a person. Stock photos of smiling strangers do the opposite.
6. Scarcity
Scarcity is the tendency to value things more when they are limited or becoming harder to get. In a 1975 study, Stephen Worchel, Jerry Lee and Akanbi Adewole found cookies from a jar with few cookies were rated as more desirable than the same cookies from a full jar, and were rated higher still when the jar went from full to nearly empty.
On a website, scarcity is real stock levels, real deadlines and real limited editions. It is also the principle most often faked, with countdown timers that reset and stock warnings that are always on. The full guide to scarcity marketing covers how to use it honestly, and the scarcity marketing examples show how well-known brands do it.
7. Unity
Unity is the pull of shared identity: we say yes more readily to people we see as one of us, whether family, a hometown, a profession or a community. It goes further than liking, which is about feeling similar. Unity is about belonging to the same group.
On a website, unity shows up when a business speaks honestly to a community it is part of: written by practitioners for practitioners, founders for founders, runners for runners. It only works if the shared identity is real.
Cialdini's principles vs Aristotle's three modes of persuasion
Aristotle's three modes of persuasion, ethos, pathos and logos, describe how an argument persuades: through the speaker's credibility, the audience's emotions and the logic of the case. Cialdini's principles describe the mental shortcuts that make people say yes. A persuasive page needs both: a sound argument, and the cues that let people trust it quickly.
| Mode | Meaning | On a website | Closest Cialdini principles |
|---|---|---|---|
| Ethos | The credibility of the speaker | Who you are, your experience, your proof | Authority, liking, social proof |
| Pathos | The emotions of the audience | The problem and the outcome, told in the customer's words | Liking, unity, scarcity |
| Logos | The logic of the argument | Clear facts, specifics, prices, comparisons | Commitment and consistency |
Persuasion vs manipulation: where is the line?
Persuasion helps people make a decision they will be glad they made, using information that is true. Manipulation gets a decision people would not make if they saw the full picture, often using information that is false or hidden. A simple test: would you be comfortable if the customer saw exactly what you did and why?
Regulators now name the manipulative versions. The US Federal Trade Commission's 2022 staff report "Bringing Dark Patterns to Light" lists practices including baseless countdown timers, false activity messages such as invented counts of people viewing an item, and drip pricing that reveals fees late. Every one of them is a faked version of a principle in this guide.
- Every review, count and "most popular" label is real and current
- Every deadline and stock message reflects real limits
- Every credential, certification and logo is earned and checkable
- Free offers are free, with no hidden sign-up
- First steps say clearly what comes next
- Prices, fees and renewal terms are shown before the decision
Do the principles of persuasion work on AI agents?
The principles of persuasion were found in people, and AI agents acting for shoppers do not feel social pressure or fear of missing out. What an agent can do is read evidence: review counts, ratings, credentials, real stock levels and deadlines stated in the page. The honest versions of the principles are data an agent can use. The faked versions are worthless to it, or worse.
This is a new field, and nobody, Convertica included, has years of data on how agents weigh these signals. The safe course is the same one this guide recommends for people: make every claim true, specific and readable in the page itself. The free CRO audit includes a check on whether AI agents can read your page.
Related persuasion guides
Questions about the principles of persuasion
What are the 7 principles of persuasion?
Robert Cialdini's 7 principles of persuasion are reciprocity, commitment and consistency, social proof, authority, liking, scarcity and unity. The first six come from his 1984 book Influence. Unity was introduced in Pre-Suasion in 2016 and added to the expanded edition of Influence in 2021.
What are the 6 principles of persuasion?
The original 6 principles of persuasion, from Cialdini's 1984 book Influence, are reciprocity, commitment and consistency, social proof (sometimes called consensus), authority, liking and scarcity. Unity, the seventh, was added later.
What are the three principles of persuasion?
The three principles of persuasion usually means Aristotle's modes of persuasion: ethos (the credibility of the speaker), pathos (the emotions of the audience) and logos (the logic of the argument). They describe how an argument persuades, while Cialdini's principles describe the mental shortcuts that make people say yes.
Which principle of persuasion is the most effective?
No single principle is always the most effective. It depends on the situation: social proof helps most when people are uncertain, authority when the decision needs expertise, scarcity when availability is genuinely limited. Testing is the only way to know which works best on your own website.
Are the principles of persuasion ethical?
The principles themselves are neutral. Using real reviews, real credentials and real stock levels is ethical persuasion. Inventing reviews, faking scarcity or implying authority you do not have is manipulation, can break consumer protection law, and damages trust once customers notice.
What is persuasion in the marketing mix?
In the marketing mix, persuasion sits mainly within promotion: the messages, proof and presentation that move a buyer from interest to action. On a website, the principles of persuasion show up in how offers, reviews, guarantees, credentials and calls to action are presented.
Research cited
- Cialdini, R. B. (1984). Influence: The Psychology of Persuasion. Expanded edition 2021; timeline at cialdini.com/about. Principles summarized by Influence at Work: influenceatwork.com/7-principles-of-persuasion
- Cialdini, R. B., and Goldstein, N. J. (2004). Social influence: Compliance and conformity. Annual Review of Psychology, 55, 591 to 621. doi.org/10.1146/annurev.psych.55.090902.142015
- Strohmetz, D. B., Rind, B., Fisher, R., and Lynn, M. (2002). Sweetening the till: The use of candy to increase restaurant tipping. Journal of Applied Social Psychology, 32(2), 300 to 309. doi.org/10.1111/j.1559-1816.2002.tb00216.x
- Freedman, J. L., and Fraser, S. C. (1966). Compliance without pressure: The foot-in-the-door technique. Journal of Personality and Social Psychology, 4(2), 195 to 202. doi.org/10.1037/h0023552
- Goldstein, N. J., Cialdini, R. B., and Griskevicius, V. (2008). A room with a viewpoint: Using social norms to motivate environmental conservation in hotels. Journal of Consumer Research, 35(3), 472 to 482. doi.org/10.1086/586910
- Worchel, S., Lee, J., and Adewole, A. (1975). Effects of supply and demand on ratings of object value. Journal of Personality and Social Psychology, 32(5), 906 to 914. doi.org/10.1037/0022-3514.32.5.906
- US Federal Trade Commission (2022). Bringing Dark Patterns to Light, staff report. ftc.gov/reports/bringing-dark-patterns-light