Cialdini's six principles

Cialdini’s six principles (from Influence) are the persuasion levers that reliably move people from “I’m thinking about it” to “okay, fine”. Almost every CRO tactic in the wild is an application of one of the six.

The six:

• Reciprocity - people feel obligated to return favours. Free samples, free shipping, free guides, free consultations. The favour creates a debt the recipient wants to repay.
• Commitment and consistency - once people commit to a small action, they’re more likely to follow through on a larger one. Multi-step opt-ins, micro-commitments before checkout, “yes ladders” in sales copy.
• Social proof - people look to others’ behaviour to decide their own. Reviews, ratings, “10,000 customers”, testimonials, user-generated content.
• Authority - people defer to credible sources. Expert endorsements, certifications, press logos, white-coat marketing.
• Liking - people are more easily persuaded by people they like. Founder stories, brand personality, shared values, attractive imagery.
• Scarcity - people want what’s rare. Limited editions, low-stock warnings, deadlines, “only X left”.

Cialdini added a seventh in later editions: unity, the sense of shared identity. Brands that explicitly position around a community (“for runners”, “by women, for women”) are leaning on unity.

How they show up in CRO tests

Most “winning” CRO tests are just better applications of one of these levers. A new urgency mechanic is scarcity. A reviews widget is social proof. A money-back guarantee is reciprocity (you take risk off the buyer). A “founder’s letter” page is liking and authority combined.

Useful as a checklist when designing tests: which of these is your page underusing? Most B2C eCommerce sites overuse social proof and scarcity and underuse authority and reciprocity. Most B2B SaaS sites overuse authority and underuse social proof.

This pairs naturally with the offer. Many offer improvements are Cialdini principles dressed up. Guarantees and bonuses are reciprocity. Urgency mechanics are scarcity. The discipline of mapping your offer to which principle it leans on tells you what’s missing.

How these get misapplied

• The mechanic without the substance. A money-back guarantee that’s deliberately hard to claim isn’t reciprocity, it’s a lie with a reciprocity-shaped wrapper. The principles describe why something works when it’s real. Implementing the surface and skipping the substance gets you the visual language of trustworthiness and none of the effect, and customers who test the claim find out.
• Social proof below critical mass. A widget proudly displaying “1 review (5 stars)” is evidence of an absence. Below some threshold the proof inverts and you’re better showing nothing at all - which is genuinely counterintuitive, because the instinct is that some proof beats none.
• Stacking. A page running urgency and social proof and authority and reciprocity at once doesn’t read as four times as persuasive, it reads as a high-pressure pitch. Confidence is itself a signal, and a page that deploys every lever simultaneously signals that it needs to.