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.

Things people get wrong

• Using scarcity dishonestly. Fake countdown timers, manufactured “low stock” warnings. Effective short-term, corrosive long-term. Customers notice and the trust hit is bigger than the conversion lift.
• Using social proof at low volume. A “1 review (5 stars)” widget signals a lack of social proof. Better to show no reviews than 1.
• Treating Cialdini as a tactical checklist without understanding the underlying psychology. A money-back guarantee that’s hard to actually claim isn’t reciprocity, it’s a lie.
• Stacking too many principles on one page. A landing page running urgency + social proof + authority + reciprocity simultaneously looks like a high-pressure sales pitch, not a confident brand.