Influence: Cialdini’s 6 Principles of Persuasion – #3 Social Proof


What do you do if you walk down the street and see a group of people looking up in the air?

Exactly. What they do. 

What if the culture at your job is to work long hours? You will likely put in more hours, too. 

We mirror what others do because it’s hard work to constantly ask ourselves: “What’s the right thing to do in this situation?” It’s much easier just to copy what others do, which to us seems socially acceptable.

Social Proof is just one of six powerful psychological forces of persuasion — together with Reciprocity, Commitment and Consistency, Liking, Authority, and Scarcity.

Let’s take a closer look at how and why social proof is a very influential power. 

Social proof is our shortcut to easier decisions 

We study other people to figure out our next moves. If a significant number of people act a certain way, the more legitimate it feels to mirror that behavior.

Broadcasting your personal life online was once for the outliers (did you know?), but that has undoubtedly changed. Bitcoin was ridiculed in 2013 when it traded at $50. Now, people can’t get enough at 2022 prices above $40,000.

Popularity by social acceptance is a shortcut for us to make easier decisions. We’re like the little kids that Cialdini writes about in Influence:

  • Boy A is afraid of dogs.
  • Boy A sees Boy B play with a dog.
  • Boy A is no longer afraid of dogs.

Examples of social proof in sales and marketing

Businesses also prey on social proof to make an extra dollar.

They know that everyone and their mother are influenced by “the popular vote,” such as:

  • Followers and likes
  • Rankings
  • User reviews
  • Poll results
  • Case stories about people we identify with (or aspire to be like)
  • Brand names
  • Product market leaders
  • Fastest growing product line 
  • Most units sold
  • Lines outside stores, restaurants, or nightclubs

Laugh, and others follow

In Influence, Cialdini also brings up canned laughter on tv shows. Various studies show that inserted laughter makes people more prone to smile, laugh and rate a show as ‘funnier’ than if there weren’t canned laughter. 

If one of your friends starts to laugh, you laugh first, and then you ask: “What’s so funny?” 

The dangers of social proof and groupthink

People with authority and power – presidents, cult leaders, even office managers – can enormously impact how large groups of people behave.

If you get a few influential people to endorse you, you begin to validate a belief or behavior that can transfer to larger groups. More and more people might follow because we mirror others.

To paraphrase Cialdini:

“To convince some people can be enough to convince the rest.”

Robert Cialdini, “Influence: The Psychology of Persuasion.”

Examples? Just think of biker gangs, Scientology, or the stock exchange.

Social proof is the ugly cousin of groupthink: most people prefer to mute their critical sense if the alternative is to break the uniformity.

The Big Short

You can watch (or read) The Big Short to get a real-life example of how social proof and groupthink went terribly wrong.

The Big Short is the true story of a few investors who dared to question the strength of the US housing market before the financial crisis in 2008.

In 2007, people seemed to get rich merely by flipping real estate and timeshares, while bankers received handsome commissions to issue obscure, high-risk loans to people who couldn’t afford them.

This behavior seems ridiculous, so why did the 2008 economic meltdown shock the world? Social proof. When you see everyone party like it’s 1999, you just put on your best shirt, take on huge loans, and ask questions later.

Only a few contrarians could see the storm coming because they didn’t buy false groupthink explanations from economists, bankers, or the Fed.


Do you think of yourself as a free and independent thinker? Most people would like to. But chances are that you’re not.

The idea of individual choice is just that: a great idea. The same goes for critical thinking. There is too much evidence that people are merely a weird mix of what other people do, say, and think.

Just 5 percent are actual first movers. The other 95 out of 100 people (including this writer) prefer to enter the game a little after kickoff. It feels so comforting to see others make the first move, doesn’t it?

Maybe the world doesn’t need more first movers. But we could use more contrarians in a world full of social proof.

By Kristian Magnus

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