Social Proof: Why We Tend to Copy Others

Social Proof: Why We Tend to Copy Others - Fallacy in Logic

Have you ever given thought to how much your choices — both large and small — are influenced by others around you? As with all of us, the answer is that probably more than you realize.

There is also a name for it: social proof.

Social proof is a common cognitive bias that describes how we tend to copy the behaviors of other people. It’s a tendency that is deeply seated in our psychological landscape and, as such, ends up flying under our radar most of the time.

In this article, we’ll explain in detail how it works and what its consequences are.

What Is Social Proof?

Social proof is a bias whereby we follow the actions and beliefs of other people around us.

For example, you may choose a hobby based on a specific recommendation from someone you know or the clothes you wear based on what’s popular among your friend group.

The term was coined by Roberto B. Cialdini, a professor of psychology at Arizona State University, who wrote about it in his psychology classic Influence: The Psychology of Persuasion. He writes:

We will use the actions of others to decide on proper behavior for ourselves…The greater the number of people who find any idea correct, the more the idea will be correct.

Importantly, it sways our behavior especially strongly when we feel uncertain of how to act; we turn to other people for clues and adopt the ways that will be approved by people in our surroundings. As such, the underlying assumption behind it is that others know more about the current situation than we do.

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Here are a couple of examples to better visualize the bias.

Buying a Car

Recently, “Jim” has been thinking of getting a new car; his current one is starting to get too outdated to his taste.

Now, since he doesn’t know that much about cars, he is sure to do thorough research on the topic: He looks up a wide range of different cars, their individual specifications, advantages over other models, and the mileage and upkeep costs of each car.

After a few days of researching and pondering, he has reduced the options down to two, but hasn’t been able to decide yet which one he should buy; they both seem to be perfect for his purposes.

However, upon hearing about Jim’s choices, his friend Alice told him there’s another option he should consider — a car that several Alice’s acquaintances drive too. As a result, Jim makes his mind and chooses to purchase the car his friend recommended, despite the fact that it doesn’t suit his needs as well as the original choices.

A Night Out

Here’s a good example given by Rolf Dobelli in his best-selling book The Art of Thinking Clearly:

You are on your way to a concert. At an intersection, you encounter a group of people, all staring at the sky. Without even thinking about it, you peer upwards too.

In the middle of the concert, when the soloist is displaying absolute mastery, someone begins to clap and suddenly the whole room joins in. You do, too.

After the concert you go to the coat check to pick up your coat. You watch how the people in front of you place a coin on a plate, even though, officially, the service is included in the ticket price. What do you do? You probably leave a tip as well.


Social Proof: Why We Tend to Copy Others - Fallacy in Logic

The effects of social proof can be both positive and negative.

It evolved, like other deeply rooted biases, to be a part of our cognition for a reason: it helps us to survive. For instance, imagine a small group of humans walking in the African savannah around 30,000 years ago. All of a sudden, everyone in the group starts sprinting towards safety as quickly as they can — except one, who neither sees the approaching lion nor realizes to simply follow others. Consequently, he ends up exiting the gene pool, while all the others survive.

Another benefit, that relates more to modern times, is that it helps to ensure our social inclusion; when we imitate others around us, we gain social acceptance and approval.

On the flip side, the reality is that the crowd is frequently mistaken, and following it may well get us into trouble. A prime example is stock market bubbles: more and more people pour money into certain popular assets, causing the prices to eventually crash and a majority of the participants to lose money.

Additionally, it can lead us to make decisions — that don’t really serve our own best interest — in a broad range of everyday situations: when choosing our hobbies, what clothes to wear, or when buying a new car.


The use of social proof is a widely adopted tactic in marketing: Marketers in all types of businesses and industries utilize it to promote their brand and increase sales of their products.

The most common form of this is testimonials and product reviews.

Most people are interested what the existing customers have to say about the products or services they’ve purchased and, subsequently, use that information in their own buying decision. As such, marketers use this fact to their advantage by placing positive testimonials where the potential customer is likely to see it.