Nudge Wiki

Concept

Liking (Similarity and Warmth)

persuasion similarity influence

One of Robert Cialdini's six original principles of influence: people are more easily persuaded by, and more willing to help, people they like — and liking is driven heavily by similarity, even superficial similarity a person isn't consciously aware of. A request from a close friend succeeds where an identical request from a total stranger fails, and the same gap opens up, in smaller form, from shared names, shared backgrounds, or other incidental points of resemblance.

Even a shared first initial shifts real purchase behavior. Across five separate studies by researcher Brendel, customers were measurably more likely to buy a product when the brand name shared its initial letters with their own name — someone named Phil, for instance, showing elevated preference for "Philips" over an equivalent competing brand, with no conscious awareness the name similarity was influencing them.

A shared name nearly doubled survey response. Researcher Garner sent identical mailed surveys, varying only the sender's name to closely resemble the recipient's own — Robert Greer's survey arrived from "Bob Gregar"; Cynthia Johnston's from "Cindy Johansson." This small manufactured resemblance nearly doubled the survey completion rate compared to a dissimilar sender name (see Liking Name-Similarity Studies).

Applied online: welcome messages that humanize a brand (e.g. "welcome to our newest course, we're happy you're here") measurably raise conversion on landing pages, per a 2017 analysis of 6,000 A/B tests (see Cialdini Principles A/B-Test Meta-Analysis (2017)). Marketing-examples writer Harry Dry's exit-intent pop-up — appearing only as a visitor tries to leave his site — drives roughly 50% of all his newsletter subscribers, more than every other sign-up prompt on his site combined, plausibly because visitors who've already engaged with (and like) his content respond differently to a request at the moment of leaving than a first-time visitor would.

Cross-cultural variation: research by Citibank found liking is the dominant persuasion principle specifically in South American countries, where people evaluating a request tend to ask "is this person connected to a friend of mine?" — a different default question than the one dominant in the US/UK (reciprocity), the Netherlands/Nordics/Germany (consistency), or parts of Asia (authority) (see Citibank Cross-Cultural Persuasion Study).

Mimicry as unconscious similarity-signaling, and its real-world persuasive power (Episode 246). Will Storr frames humans as constantly in "detect and connect" mode, seeking cooperators who see the world the way they do — which is why mimicking another person's language, gestures, and manner builds rapport and trust. A high-stakes real example: Nelson Mandela defused tension with a hardline Afrikaner general by greeting him warmly in Afrikaans rather than English, a gesture the general later returned by addressing Mandela's own retirement tribute in Xhosa (see Mandela Fouilon Afrikaans-Mimicry Case). Controlled studies show the same mimicry operating entirely below conscious awareness: participants unknowingly copy a conversation partner's face-rubbing or foot-shaking, and unknowingly eat more of a snack, and rate it more positively, after watching someone else eat it on video (see Chameleon Effect Mimicry Studies). At scale, a study of 421 million potential matches on a dating site found similarity was the single best predictor of romantic interest, predicting a match with 60% accuracy (see Levy Markle Cerf Dating-Similarity Study), and a 1971 field study found protest petitioners were far more likely to get a signature from someone dressed similarly to the person approaching them, regardless of the pitch itself (see Suedfeld Bochner Matas Clothing-Similarity Petition Study (1971)).

Applied to advertising and identity-based branding. Storr quotes David Ogilvy: persuasive communication should use "their language, the language they use every day, the language in which they think" — advertising works best as a mirror showing an audience who they already believe themselves to be. Apple's "Think Different" campaign (images of Gandhi, Lennon, Mother Teresa, Martin Luther King, with no product shown at all) sold an identity — "our computers are for the people who want to change the world" — rather than any product feature (see Steve Jobs). Molson Beer's "The Rant," an ad with zero product information built entirely around Canadian identity and resentment at being mistaken for American, added tens of millions of dollars to the company's value within weeks of airing (see Molson Canadian 'The Rant' Identity Ad Case). A University of Arizona campaign cut student binge drinking by nearly 30% simply by correcting the misperception that heavy drinking was the norm among peers, rather than warning about health risks (see University of Arizona Binge-Drinking Dynamic-Norm Campaign).

A classic identity-priming donation study, re-cited (Episode 246). Storr also re-cites the 1994 "I'm a student here too" campus donation study already documented under Unity (Cialdini's Seventh Principle) (see Ohn Basil 1994 Campus Donation Unity Study), framing it through the lens of similarity/mimicry rather than unity specifically — the same underlying mechanism viewed from two closely-related angles.

A dense return to the principle via a second Cialdini guest episode (Episode 276). Salesperson likability strongly predicted how trustworthy 238 business buyers judged a supplier's rep, independent of actual track record (see Nicholson Compeau Sethi Salesperson Likability-Trust Study). Trader Joe's and Walmart both deliberately hire and train front-of-store staff for warmth (see Trader Joe's and Walmart Greeter Friendliness Cases). A friendly restaurant owner was judged 37% more likely to pay their taxes on time than a sullen one, despite friendliness having no logical bearing on tax compliance (see Stanley Shotton Friendly-Owner Tax-Perception Study). An evaluator known to need a favor was liked best for pure praise regardless of whether it was true (see Drachman deCarufel Insko Extra-Credit-Effect Study (1978)). A free-gum-with-the-bill gift raised a Krakow restaurant's tips from 10.5% to 14.1%, replicating the mint-tipping mechanism outside the US (see Gladka Zemla Krakow Gum-Tipping Replication). A landing-page welcome message ranked 6th of 29 tested conversion features across 6,700 A/B-tested websites (see Browne Swarbrick-Jones 6,700-Website A/B Test Study). And mood transfer alone can substitute for genuine liking: political statements rated during a free lunch got higher approval (see Razran Luncheon Technique Study), and Israeli parole rulings favored defendants roughly 65% of the time right after a judge's lunch break, falling toward 0% before the next one (see Danziger Levav Avnaim-Pesso Judicial Lunch-Timing Study).

Discussed in

  • Episode 207 — 207-is-the-godfather-of-influence-still-relevant
  • Episode 246 — 246-a-surprisingly-effective-way-to-persuade-almost-anyone (Mandela; chameleon-effect mimicry studies; dating and clothing similarity studies; Ogilvy; Think Different; Molson; binge-drinking campaign)
  • Episode 276 — 276-robert-cialdini-this-study-on-6-700-websites-proved-my-principle (salesperson-trust study; Trader Joe's/Walmart; friendly-owner tax study; extra-credit-effect study; Krakow gum replication; 6,700-website study; luncheon technique/judges'-lunch study)

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