Influence: Why You Keep Buying Stuff You Don’t Need

(and How to Spot the Jedi Mind Tricks)

Intro: The Godfather of Persuasion

If you’ve ever impulse-bought a kitchen gadget after watching a late-night infomercial, congratulations: you’ve been Cialdinied.

Robert Cialdini, a psychology professor, spent years going undercover with salespeople, fundraisers, and advertisers to figure out why humans say yes. The result, Influence (1984, updated since), is the bible of persuasion.

The scary part? These principles work on everyone. Even you, even me, even the friend who swears they’re “too logical” for marketing tricks.

Cialdini distills persuasion into six weapons (later seven):

Reciprocity
Commitment & Consistency
Social Proof
Liking
Authority
Scarcity
(+ Unity, added later)

Let’s break them down Substack-style: clear, funny, with enough real-life examples that you’ll start seeing them everywhere (and probably curse Cialdini a little).

1. Reciprocity: The Free Sample Scam

Humans are wired to return favors. If someone does something for us, we feel obligated to do something back.

That free Costco sample? Reciprocity.
The charity that sends you “free” address labels in the mail? Reciprocity.
Your friend spots you coffee, you feel you owe them lunch.

Cialdini shows how powerful this is. Even tiny gifts create huge compliance.

Weaponized example: Hare Krishnas in airports used to hand people flowers before asking for donations. People gave money just to get rid of the guilt.

Modern meme version: SaaS companies giving you a “free trial.” Reciprocity makes you more likely to subscribe.

2. Commitment & Consistency: The Foot-in-the-Door Trick

We want to appear consistent. Once we commit, even in small ways, we’ll act in line with that commitment.

Classic study: Researchers asked homeowners to put a tiny “Be a Safe Driver” sticker in their window. Later, those same people were far more likely to agree to a giant ugly yard sign about driving safety.

Why? Because saying yes once primes you to say yes again.

Modern life:

Subscriptions with “start free, cancel anytime.” You commit, then inertia keeps you.
Social media activism: post a hashtag once, feel obligated to keep supporting.
Dating: first date coffee → second date dinner → moving your stuff into their apartment.

Consistency is comforting, but it also locks us in.

We assume if everyone else is doing something, it must be good.

Laugh tracks in sitcoms.
Yelp reviews.
“Bestseller” tags on Amazon.

One study: when a hotel put a card saying “75% of guests reuse towels”, towel reuse shot up. Social proof beats guilt-tripping about the planet.

This is why influencers exist. If enough people appear to like something, you assume you should too.

Cue FOMO. Cue TikTok trends. Cue you buying Stanley cups you don’t need.

4. Liking: The Attractive Salesperson Effect

We say yes more often to people we like. And what makes us like people?

Attractiveness: Hot people get more compliance. (Science, not just high school.)
Similarity: “You’re from Ohio? I’m from Ohio!” Boom, instant bond.
Compliments: Flattery works, even when we know it’s flattery.
Familiarity: The more we see someone, the more we like them.

That’s why sales reps try to mirror your body language, find common ground, and call you “buddy.”

Modern analogy: ever notice how MLMs recruit through friends? You’re not buying essential oils, you’re buying because your friend asked.

5. Authority: The Lab Coat Effect

We’re wired to obey authority figures. Titles, uniforms, symbols of expertise trigger compliance.

The infamous Milgram experiment showed ordinary people would deliver what they thought were deadly shocks — just because a guy in a lab coat told them to.

Today, authority shows up as:

Doctors in ads recommending toothpaste.
Influencers “certified” in nonsense.
Job titles making people’s opinions carry more weight, even when irrelevant.

Logos, suits, jargon — all little signals of authority.

6. Scarcity: The “Only 2 Left!” Scam

Nothing makes us want something more than the idea it’s running out.

“Limited time offer!”
“Only 3 seats left at this price!”
“This deal ends in 2 hours.”

Scarcity flips a switch in the brain: if it’s rare, it must be valuable.

In one study, people rated cookies more desirable when they came from a jar with 2 cookies than from a jar with 10. Same cookie, different scarcity.

Modern world = Amazon Lightning Deals, sneaker drops, crypto pumps. Scarcity creates urgency, urgency overrides rational thought.

(Bonus) 7. Unity: The Newest Trick

In later editions, Cialdini added a seventh principle: Unity.

This is the feeling of shared identity: we are family, tribe, insiders. When someone sees you as part of their “us,” persuasion skyrockets.

Think:

Political slogans like “We the People.”
Brands creating communities (Harley-Davidson riders, Apple users).
Sports fandom.

Unity isn’t just liking someone. It’s merging your identity with theirs. Once you’re in the tribe, saying no feels like betrayal.

Putting It All Together: Why You Keep Falling for This

Picture this: You walk into a store.

Salesperson greets you warmly (liking).
Offers you a free sample (reciprocity).
Mentions “most people buy two” (social proof).
Wears a sharp suit and Rolex (authority).
Says “this offer ends today” (scarcity).
Gets you to commit with a small “would you like me to hold it at the counter?” (consistency).
And reminds you “smart shoppers like us know value when we see it” (unity).

Congrats, you’re buying.

Applications (a.k.a. How to Use Your New Powers)

Ethically applied, Cialdini’s principles are tools for persuasion in everyday life:

Reciprocity: Do favors without keeping score. People naturally return them.
Commitment: Start small when convincing others. Micro-yeses lead to big yeses.
Social Proof: Highlight how many others already benefit.
Liking: Build rapport genuinely — find real similarities.
Authority: Signal expertise without arrogance.
Scarcity: Highlight what’s unique, rare, or time-sensitive.
Unity: Frame goals as collective, not individual.

Criticism & Caveats

Some say Cialdini’s book arms manipulators. Fair. But knowledge cuts both ways: knowing these tricks also makes you resistant to them.

Also, persuasion isn’t magic. Long-term influence comes from trust and authenticity. If you fake it, people eventually sniff it out.

TL;DR (For the Easily Persuaded)

Reciprocity: Free sample = you owe me.
Consistency: Say yes once, you’ll say it again.
Social Proof: Everyone’s doing it.
Liking: We say yes to people we like.
Authority: Obey the lab coat.
Scarcity: FOMO drives desire.
Unity: We > me.

Or, meme version:

Me: “I’m not buying anything today.”
Salesperson: hands me free cookie sample
Me: “Okay fine, I’ll take three.”