Everyone Else Was Doing It: Social Proof

15.12.2017 |

Episode #1 of the course How cognitive biases are messing up your decisions by Abasi Latcham


You are not as logical, rational, or deliberate in your decisions as you think. This is because all humans are susceptible to what psychologists and behavioral economists call, “cognitive biases.” Basically, a cognitive bias is a shortcut that your brain uses because it is fundamentally lazy. The technical definition from the Encyclopedia of Human Behavior is a “systematic error in judgment and decision-making common to all human beings which can be due to cognitive limitations, motivational factors, and/or adaptations to natural environments.”

This course is going to introduce you to ten biases, explain them, provide examples, and help you make better decisions by being aware of their influence. We are going to start with social proof.


What Is It?

Social proof is the tendency of people to imitate others when unsure of how to behave. Given a situation where there is uncertainty, your brain will look to see how other people are behaving and use their actions as a basis for what is “correct” (“correct” might mean best or appropriate, etc.; it is context specific). While this often makes sense, it is based on the premise that the other people hold some special information that you lack.

Consider this example. You are out with friends for dinner. You chance across two restaurants next to one another, both empty. You decide to try the left restaurant. Several minutes later, another group comes upon the same restaurants. However, this time, they see that one is empty and one has customers. They figure the one with customers must be better (why else would the customers be there?), so they, too, enter the left restaurant. This repeats throughout the night, until several hours later, the left restaurant is full, and the one on the right is trying to figure out why they’re having such a slow night. Social proof makes us think, “If lots of people are doing something, there must be a good reason why.”



The effects of social proof can range from the benign to the terrible. Consider these examples, roughly ordered from harmless to harmful.

Wanting to go somewhere because it has a queue: If all those people are waiting to get into that place, it must be good!

Testimonials/the “most popular”: Any time you see that something is the “most popular,” your brain thinks, “popular = good.”

Laugh tracks: TV shows use laugh tracks as social proof to make jokes seem funnier.

The Bystander Effect: The corollary of social proof is not acting because others aren’t acting, known as the bystander effect. This is illustrated by the case of 2-year-old Wang Yue, who was run over by two trucks, in front of witnesses, after which 18 people ignored her injured body before someone eventually called for help.

The Werther Effect: The Werther Effect suggests that portrayals of suicide in the media acts as social proof and lead to an increase in copycat suicides.



Nine times out of ten, social proof provides us with the correct answer and saves our brain precious energy. But that one other time can lead us astray. Robert Cialdini, a professor of psychology, likens social proof to autopilot in an airplane and argues that if we can recognize situations where it’s acting on inaccurate information, we can reassert control. He argues that inaccurate information occurs in two types of situations.

The first is where the social evidence has been purposely falsified, such as laugh tracks. The presence of these forms of social proof should trigger warning bells that alert you to the fact that you’re only seeing the responses of those who support the “product,” and indeed, this support may very well be counterfeit.

The second type of situation is where benign social proof errors snowball into calamity. The restaurant example above exemplifies this. If you ever find yourself thinking, “Everyone else is doing it,” take a second to consider what they are doing, and ask if there is any other evidence advocating for their behavior.

Tomorrow, we will cover anchoring and look at how your brain gets stuck on the first bit of information it hears.


Recommended book

Influence: The Psychology of Persuasion by Robert Cialdini


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