You got on YouTube and search for “camping hacks” to help plan your next trip. You see a list of videos. But you don’t want some random amateur giving you advice, so you naturally pick the video with higher views. Why?

You are on your way somewhere. On the road you encounter a group of people, all staring at the sky. Without even thinking about it, you look upward, too. Why?

Informational Social Influence is a psychological and social phenomenon where people assume the actions of others in an attempt to reflect correct behaviour in a given situation.

This is more commonly known as Social proof. If a lot of people have watched a video, chances are it’s helpful. Similarly, if a lot of people are looking upwards, something might worth looking at. You make the decision without even thinking.

This ‘herd instinct’ dictates the fact that individuals feel they are behaving correctly when they act the same as others. The more people who follow a certain idea, the better (truer) you deem the idea to be. And the more people who display a certain behaviour, the more appropriate this behaviour is judged by others and you as well, no matter how absurd the idea or the behaviour is.

“Insanity in individuals is something rare - but in groups, parties, nations and epochs, it is the rule.”

—  Nietzsche

Social proof is the reason behind tech bubbles and stock market panics. It exists everywhere - in fashion, management techniques, hobbies, religion, and diets. It is the reason why something starts trending or goes viral.

You take it for granted that as a rule, you’ll make fewer mistakes by acting in accord with social evidence. Usually, when a lot of people are doing something, it is the right thing to do. In a theatre, you might start clapping when other people in the audience start clapping. After the concert, if you don’t know where the men’s section is, you might follow other men going towards a certain area.


There are four attributes in this phenomenon:

Uncertainty: When faced with an unfamiliar situation, you are uncertain about what you should do and you feel the need to refer others for guidance. You don’t know which way the washroom in the concert hall is.

Similarity: You are influenced by people who are socially and economically like you. Other men (like you) are going towards the loo to answer nature’s call.

Expertise: You perceive the surrounding people as particularly knowledgeable about the situation or are even just slightly more familiar with the situation than you are. Men are confidently going towards the loo without wandering around.

Number: The greater the number of people who find an idea to be correct, the more correct and valid the idea will seem to you. Groups of men are going towards the loo after coming out of the theatre.

All these happen automatically, without you having to make any conscious decision. Your System 1 takes care of everything.

Some practical applications of social proof are:

  1. Ecommerce websites show you number of times an item has been ordered to drive more orders. Similarly, social networks and content websites show you number of shares and views of posts to drive more shares.
  2. If you wish to collect the names and phone numbers of random people attending any random event, simply ‘salt’ a register with fake names and phone numbers, put it beside the entrance and stand beside it. Most people would comply and fill in their names and phone number without even asking. Next time, try asking for their email password for fun. See how many of them put that one as well.
  3. If you are a standup comedian, and aren’t sure if your jokes are going to click, plant some friends among the audience to provide canned laughter every time you say a bad joke. The joke wouldn’t seem to bad anymore. It works. As an alternative, also try to lookout for the decoys next time you visit a standup comedy show.
  4. All kinds of testimonials - real or staged, video or text, are good examples of the social proof put to excellent use.

This feature of mimicking others’ behaviours is simultaneously a strength and a weakness for you. It provides you convenient shortcuts for determining how to behave but at the same time it makes you vulnerable to designers and decision makers, like me.

If you upvote an already 1.5k times upvoted answer in Quora, you’ve been persuaded. Similarly, if you buy a dress because it’s in fashion today and around 2,134 people have bought it, you’ve been persuaded.

But the real problem comes when you begin responding to social proof in such a mindless and reflexive manner that you can be fooled even by evidence you know to be fake.

A good example is canned laughter in your favourite sitcom. You know that it’s not real. If asked, you might even say that you despise canned laughter. But when the show is on, canned laughter triggers your System 1 to follow social proof, even though your System 2 knows that it’s fake. How can we explain such behaviour?

Fifty thousand years ago when you were trekking with your hunter gatherer friends in the forest, and all a sudden when all of them bolted, you too bolted as well. If you had waited to find out if it was a real threat, and not the leaves moving just because of the wind, you might not have lived long.

We all are the descendants of those who followed others and bolted along - those with herd mentality. The others who waited died, and exited the gene pool. However, we still use this pattern today, even when it offers no survival advantage whatsoever. This pattern is deeply rooted in humans.

One of the most troubling cases of this phenomenon is the famous speech by Nazi propaganda minister Joseph Goebbels, delivered in 1943. As the war went worsened for Germany, he demanded to know, “Do you want total war? If necessary, do you want a war more total and radical than anything that we can even imagine today?” The crowd cheered with enthusiasm. If the attendees had been asked individually, it is very likely that nobody would have agreed to such a crazy proposal.

What you have to understand is that 95% of the people are imitators, and only 5% are initiators. People are persuaded more by the actions of others than by any proof you can offer. The phenomenon of social proof changes minds, both in positive and negative ways. But next time somebody claims something to be the truth because 1 Mn people believe in it, remember W. Somerset Maugham’s words, “If 50 Mn people say something foolish, it is still foolish.”