Cialdini's Six Principles
Reciprocity, commitment, social proof, authority, liking, scarcity.
Robert Cialdini's Influence (1984) identified six universal principles of persuasion. They work because they're hardwired — evolved responses that served our ancestors well but can be exploited in modern contexts.
1. Reciprocity
When someone gives you something, you feel obligated to give back. Free samples, favors, concessions — they all create a psychological debt. The Hare Krishnas raised millions by giving flowers to strangers in airports; people felt obligated to donate.
2. Commitment and Consistency
Once people commit to something (especially publicly), they feel pressure to behave consistently. Start small: get someone to agree to a minor request, and they're much more likely to agree to a bigger one. This is the "foot-in-the-door" technique.
3. Social Proof
When uncertain, people look at what others are doing. "50 million users" / "bestseller" / "most popular choice" — these all work because we assume the crowd knows something we don't.
4. Authority
People defer to experts and authority figures. A doctor's recommendation carries weight because of the white coat, not because patients evaluate the evidence. Titles, uniforms, and credentials all trigger this response.
5. Liking
We say yes to people we like. Similarity, compliments, familiarity, and physical attractiveness all increase liking — and therefore compliance. This is why salespeople find common ground before pitching.
6. Scarcity
"Only 3 left!" "Limited time offer!" "Exclusive access!" — scarcity increases perceived value. The fear of missing out (FOMO) is one of the most powerful motivators in human psychology.
