SKILL.md
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Why it works: Humans are wired to avoid being indebted. The obligation to repay is so strong that it can overpower other factors like personal preference or fairness.
Key insights:
- The gift must come first (before the request)
- Personalization increases power
- Unexpected gifts are more powerful than expected ones
- Even small gifts create obligation
- The return favor often exceeds the original gift
Product applications:
Context
Reciprocity Trigger
Example
Free trials
Give full access first, then ask to pay
Spotify Premium trial → subscription
Content marketing
Provide value upfront (guides, tools)
HubSpot free CRM → paid tools
Referral programs
Give reward to both referrer and referee
Dropbox: both get extra storage
Onboarding
Unlock a premium feature temporarily
Grammarly: free tone detection trial
SaaS
Provide unexpected value or support
Personalized setup call for new users
Copy patterns:
- "Here's a gift for you..." (before asking)
- "We've upgraded your account..."
- "As a thank you for signing up..."
- "We noticed you needed help with X, so we..."
Ethical boundary: Give genuine value. Don't create artificial debts or exploit obligation.
See: references/reciprocity.md for reciprocity techniques and case studies.
2. Commitment & Consistency
Core concept: People want to be consistent with their past statements, beliefs, and actions.
Why it works: Inconsistency is psychologically uncomfortable. Once we've made a choice or taken a stand, we encounter personal and interpersonal pressure to behave consistently with that commitment.
Key insights:
- Small initial commitments lead to larger ones (foot-in-the-door)
- Public commitments are stronger than private ones
- Written commitments are stronger than verbal ones
- Active commitments (user-generated) are stronger than passive ones
- Self-perception: we infer our attitudes from our behavior
Product applications:
Context
Commitment Trigger
Example
Onboarding
Start with easy yes, build to larger asks
Duolingo: "Can you commit to 5 min/day?"
Progressive profiling
Small data requests that compound
LinkedIn: add photo → headline → experience
Goal setting
User publicly states a goal
Strava: "I want to run 50km this month"
Social proof generation
Ask for review after positive action
Airbnb: review request after good stay
Habit formation
Track streak publicly
Snapchat streaks, GitHub contributions
Copy patterns:
- "What's your biggest challenge with X?" (commitment to a problem)
- "How much would you like to save per month?" (numerical commitment)
- "Would you like to join X people who've already...?"
- "You said you wanted to achieve X. Let's start with..."
Onboarding sequence:
- Get micro-commitment ("What brings you here?")
- Small action (click, choice, input)
- Public or written commitment (goal, preference)
- Reinforce consistency ("Based on what you told us...")
Ethical boundary: Don't lock users into commitments they didn't freely make. Allow easy reversibility.
See: references/commitment-consistency.md for commitment tactics and flows.
3. Social Proof
Core concept: People determine what's correct by finding out what other people think is correct.
Why it works: When uncertain, we look to others' behavior as a guide. "If everyone's doing it, it must be right."
Key insights:
- Most powerful when observers are uncertain
- Similar others = stronger proof (age, location, goals)
- Negative social proof can backfire ("9 out of 10 don't...")
- Specific numbers > vague claims ("2,347 users" > "thousands")
- Live activity = urgency + proof
Types of social proof:
Type
Definition
Example
Wisdom of crowds
Many people use/buy
"Join 50,000+ marketers"
Wisdom of friends
People you know use it
"3 of your friends use Notion"
Expert
Authorities endorse
"Recommended by Y Combinator"
Celebrity
Famous people use it
"Used by Elon Musk"
Certification
Third-party validation
"SOC 2 compliant", "App of the Year"
User
Similar people succeeded
"Startups like yours grew 10x"
Product applications:
Context
Social Proof Implementation
Example
Landing pages
User count, reviews, logos
"Trusted by 10,000+ companies"
Signup flow
Live signups, popular plans
"23 people signed up in the last hour"
Feature adoption
Show usage by others
"85% of teams use this feature"
Urgency
Limited availability
"Only 3 spots left at this price"
Reviews
Ratings, testimonials, case studies
G2 badges, video testimonials
Copy patterns:
- "[X number] of [similar people] are already..."
- "[Name/Company] increased [metric] by [%]"
- "Don't take our word for it. Here's what [users] say..."
- "Join [X] others in [cohort]"
Ethical boundary: Never fabricate social proof. Real numbers, real testimonials. Disclose when proof is curated.
See: references/social-proof.md for social proof types and implementation patterns.
4. Authority
Core concept: People follow the lead of credible, knowledgeable experts.
Why it works: Obedience to authority is deeply ingrained. Following experts is an efficient shortcut when we lack expertise ourselves.
Key insights:
- Titles, credentials, uniforms trigger automatic compliance
- Authority is conferred (doctors, professors) and assumed (confident tone)
- Admitting a weakness paradoxically increases authority (trustworthiness)
- Expertise in one domain doesn't transfer, but people assume it does
- Even symbols of authority work (lab coats, official-looking designs)
Sources of authority:
Type
Signal
Example
Credentials
Degrees, certifications
"Built by Stanford PhDs"
Experience
Years in field, track record
"20 years in cybersecurity"
Social proof
Awards, press, rankings
"Featured in Forbes, TechCrunch"
Association
Trusted partners, investors
"Backed by Y Combinator"
Content
Thought leadership, research
"Based on research with 10,000 users"
Transparency
Honest about limitations
"Works best for teams of 10-50"
Product applications:
Context
Authority Trigger
Example
About page
Founder credentials, team expertise
"Built by ex-Google engineers"
Content
Original research, whitepapers
"State of [Industry] 2026 Report"
Product UI
Professional design, data citations
Charts with "Source: X Study"
Support
Expert consultations, certifications
"Talk to a certified expert"
Partnerships
Integration badges, security certs
"SOC 2 Type II", "GDPR compliant"
Copy patterns:
- "Trusted by [authority figure/company]"
- "Certified by [credible third party]"
- "Research shows that [cite source]..."
- "Our team includes [credentials]"
Ethical use:
- Admit weaknesses before strengths (increases trust)
- Be transparent about what you're not good at
- Cite real sources and data
- Don't overstate credentials or experience
Ethical boundary: Never fake credentials or fabricate expertise. Real authority only.
See: references/authority.md for authority-building strategies.
5. Liking
Core concept: People prefer to say yes to those they like.
Why it works: We're more persuaded by people we like, trust, and feel connected to. Liking creates psychological safety and reduces resistance.
Factors that increase liking:
Factor
Mechanism
Example
Physical attractiveness
Halo effect: attractive = good
Professional headshots, polished design
Similarity
We like people like us
"I'm a founder just like you"
Compliments
Flattery works (even when obvious)
"You have great taste in tools"
Cooperation
Working toward shared goals
"Let's build this together"
Familiarity
Repeated exposure increases liking
Consistent brand, retargeting
Association
Linked to positive things
Product placement with aspirational lifestyles
Product applications:
Context
Liking Trigger
Example
Brand voice
Friendly, conversational, human tone
Mailchimp's playful copy
Team pages
Show real people, personality
Personal bios, hobbies, photos
Onboarding
Personalized welcome, friendly UI
"Hey [Name], welcome!"
Support
Warm, empathetic responses
"I totally understand that frustration..."
Community
Facilitate connections among similar users
User groups, Slack communities
Copy patterns:
- "We're [similar trait] just like you"
- "Great choice! You clearly value [shared value]"
- "We built this because we were frustrated with..."
- Use casual, warm language ("Hey", "Awesome!", "We got you")
Ethical boundary: Be genuinely helpful and authentic. Don't manufacture false rapport or manipulate emotions.
See: references/liking.md for liking techniques and tone guidelines.
6. Scarcity
Core concept: People want more of what they can't have or what's running out.
Why it works: Loss aversion is stronger than gain seeking. The fear of missing out (FOMO) triggers urgency and desire.
Key insights:
- Scarcity of time > scarcity of quantity
- Newly scarce > always scarce (loss framing)
- Competition increases value (if others want it, I want it)
- Exclusive access is more valuable than open access
- Psychological reactance: when freedom is threatened, we want it more
Types of scarcity:
Type
Mechanism
Example
Limited quantity
Finite supply
"Only 5 seats left"
Limited time
Deadline pressure
"Offer ends Friday"
Exclusive access
Not everyone can have it
"Invite-only beta"
Unique
One-of-a-kind
"Custom built for you"
Competition
Others are competing for it
"12 people viewing this"
Product applications:
Context
Scarcity Trigger
Example
Pricing
Limited-time discount
"Early bird pricing ends in 3 days"
Features
Beta access, waitlist
"Join 5,000 on the waitlist"
Events
Limited seats, RSVP deadlines
"Only 20 spots remaining"
Inventory
Stock levels
"2 left in stock"
Urgency
Countdown timers
Real-time countdown to deadline
Copy patterns:
- "Limited to the first [X] customers"
- "Offer expires [specific date]"
- "Join the waitlist" (implies exclusivity)
- "[X] people are viewing this right now"
Ethical boundaries:
- Never fake scarcity. If there's no real limit, don't imply one.
- Avoid dark patterns: Reset timers, fake countdown clocks are manipulative.
- Allow rational decisions: Scarcity shouldn't prevent informed choice.
When scarcity is ethical:
- Real limited inventory (truthful stock counts)
- Genuine deadlines (actual event dates, seasonal offers)
- Legitimate exclusivity (beta capacity limits, cohort sizes)
When scarcity is unethical:
- Artificial scarcity (no real limit)
- Evergreen countdown timers that reset
- "Only 2 left!" repeated every day
- Pressuring vulnerable users
See: references/scarcity.md for scarcity tactics and ethical implementation.
7. Unity
Core concept: People say yes to those they consider part of "us" (shared identity).
Why it works: Tribal identity is fundamental. We make sacrifices for in-group members we wouldn't make for strangers.
Unity vs. Liking:
- Liking: "This person is like me" (similarity)
- Unity: "This person is me" (shared identity)
Sources of unity:
Type
Mechanism
Example
Family
Blood relation, chosen family
"We're family"
Place
Hometown, region, nationality
"Built in San Francisco, for founders"
Experience
Shared hardship or triumph
"We've all struggled with bad CRMs"
Values
Deep beliefs, mission alignment
"For people who value privacy"
Tribe
Co-creation, movement
"Join the indie maker community"
Product applications:
Context
Unity Trigger
Example
Brand positioning
Define the tribe
"For remote-first teams"
Messaging
"We" language, shared struggle
"We believe work should be flexible"
Community
Facilitate co-creation
User-generated content, forums
Onboarding
Identity affirmation
"Welcome to the [tribe name]"
Social features
Enable unity signals
Profile badges, group membership
Copy patterns:
- "For [identity group]" ("For designers", "For bootstrappers")
- "Join [X] others who believe..."
- "We're building this together"
- "This is for us, not them"
Ethical boundary: Don't create toxic in-groups or vilify out-groups. Unity should unite, not divide maliciously.
See: references/unity.md for unity-building strategies.
Combining Principles
The most powerful persuasion uses multiple principles together.
Example: SaaS landing page
- Authority: "Built by ex-Stripe engineers" (credentials)
- Social proof: "Trusted by 5,000+ companies" (wisdom of crowds)
- Liking: Friendly, warm copy and design
- Scarcity: "Join the beta—limited spots available"
- Reciprocity: "Start free, no credit card required"
- Unity: "For founders who move fast"
Example: Referral program
- Reciprocity: Give reward to both parties
- Social proof: "X friends already joined"
- Unity: "Invite your team"
- Commitment: After they've had a good experience
Ethical Application Checklist
Before deploying influence tactics:
- Is it truthful? No fake scarcity, fabricated proof, or false credentials
- Does it help the user? Persuasion should align with user goals, not exploit them
- Is it transparent? Are you hiding how you're influencing them?
- Is it reversible? Can users easily undo commitments?
- Would you use it on yourself/family? The golden rule of persuasion
- Does it respect autonomy? Users should feel in control, not manipulated
- Are you targeting vulnerable groups? Extra caution with children, elderly, desperate
The line between persuasion and manipulation:
- Persuasion: Helping people see value they'd appreciate anyway
- Manipulation: Tricking people into choices against their interests
See: references/ethics.md for comprehensive ethical boundaries.
Common Mistakes
Mistake
Why It Fails
Fix
Fake social proof
Destroys trust when discovered
Use real data or don't use it
Overuse of scarcity
Becomes noise, loses power
Reserve for genuine urgency
Inconsistent authority
Undermines credibility
Don't claim expertise you lack
Forced reciprocity
Feels transactional, not genuine
Give without immediate ask
Generic unity
"Everyone" is not a tribe
Define specific shared identity
Quick Diagnostic
Audit any persuasive element:
Question
If No
Action
Which principle(s) am I using?
You're relying on luck
Explicitly design for influence
Is this claim/tactic truthful?
You're manipulating
Remove or replace with truth
Would this work on me?
It probably won't work on others
Redesign with genuine value
Am I combining principles?
Missing leverage
Layer multiple principles
Can users easily reverse?
Ethical concern
Add clear opt-outs
Reference Files
- reciprocity.md: Reciprocity techniques, gift strategies, examples
- commitment-consistency.md: Commitment flows, foot-in-the-door, public commitment tactics
- social-proof.md: Social proof types, implementation patterns, case studies
- authority.md: Building authority, credentials, thought leadership
- liking.md: Liking factors, brand voice, rapport-building
- scarcity.md: Scarcity tactics, ethical vs. manipulative scarcity
- unity.md: Tribe-building, identity marketing, community
- ethics.md: Ethical boundaries, manipulation vs. persuasion
- case-studies.md: Real-world applications across industries
- copywriting.md: Influence-based copy frameworks
Further Reading
This skill is based on Robert Cialdini's research and books. For the complete science, research citations, and expanded case studies:
- "Influence: The Psychology of Persuasion" by Robert B. Cialdini (Original + Expanded Edition with Unity principle)
- "Pre-Suasion: A Revolutionary Way to Influence and Persuade" by Robert B. Cialdini (Advanced: creating privileged moments for influence)
About the Author
Robert B. Cialdini, PhD is Regents' Professor Emeritus of Psychology and Marketing at Arizona State University. His research on the psychology of influence has been published extensively and is widely cited. Influence has sold over 5 million copies worldwide and is considered the foundational text on persuasion science. Cialdini has consulted for Fortune 500 companies, government agencies, and nonprofits on ethical influence strategies.