Social Proof: These 4 principles Explain Why Social Proof is a Powerful Marketing Tool

Ever wondered why TV shows use canned laughter and why there is always money in the bartenders’ tip jars? Or why there is an increase in suicide after someone famous jumps off a building? Why it would be harder for the Queen of England to influence you than someone from your grad school? The answer is Social proof.

What is Social Proof?

Social proof is the phenomenon whereby we decide what the correct behaviour is based on those around us. It is considered to be one of the strongest tools of influence and persuasion. There are certain circumstances under which social proof works better than others, such as when the correct course of action is uncertain or when we perceive ourselves to be similar to those already engaging in the behaviour.

This article will explain why social proof is the most effective persuasion tactic available and how it can be used in marketing, plus give suggest reasons why the phenomenon is more relevant now than it has ever been.

The scientific researches behind Social proof

As sales consultant Robert Cavett famously stated, “95 % of people are imitators and only 5% initiators, people are persuaded more by the actions of others than by any proof we can offer.” Many might be sceptical of this statement. Surely, people have their own clearly established preferences and act accordingly?

Salganik et al (2008) conducted an experiment in which they aimed to examine exactly this. They created an artificial music market and manipulated people’s ratings of songs so that some which had the poorest rating were made to appear at the top of the list as “most popular”. They found that these songs were then better received by users. The legitimately popular songs still performed well, however, lower-reviewed songs became just as listened to. This study illustrates just how powerful social proof is, even when it goes against one’s own personal preference.

In an another experiment, the “fathers of persuasion” Robert Cialdini and Noah Goldstein investigated the best way to encourage environmentally friendly behaviour by persuading hotel guests to reuse their towels.

They placed different signs in washrooms and aimed to determine which mode of influence would have the largest effect. In one condition, they provided guests with a standard environmental message such as “Help save the environment. You can show your respect for nature and help save the environment by reusing your towels during your stay.” In another condition, the message read: “Join your fellow guests in helping to save the environment. Almost 75% of guests who are asked to participate in our new resource savings program do help by using their towel more than once.”

Which condition was more effective?

Did you go with B, “join your fellow guests”? If so, you guessed correctly!

The message which described the behaviour of other hotels guests resulted in significantly more towel reuse.

As with any tools of social influence, there are certain conditions in which they work better, and certain people who are more susceptible to them. What and who are they?

These 4 principles explain why social proof is so powerful

When it comes to social proof the two biggest situational factors are uncertainty and similarity.

Attractiveness and desirability also play a role. We are more likely to be persuaded through interaction with people who are perceived to be similar, attractive or desirable.

1. Uncertainty

Let’s first take a look at the situational factor of uncertainty and see how that intensifies the effect of social proof. Perhaps the most striking examples of social proof to date is the murder of Kitty Genovese in 1964 on the streets of New York. Catherine Genovese was stabbed to death by an unknown attacker.

However, what was most shocking about this incident is that it had not been a quick death. It had been a prolonged, public event and there were 38 witnesses. People on the streets of New York watched her beg for her life and did nothing. Why? How? What was going on?

Indeed, one of the principles at work was that of social proof. People looked around to see what others were doing, and since no one did anything, that was considered to be the appropriate behaviour. This was a “diffusion of responsibility.” People gave up personal liability because they expected others to take action. And so, no one did.

However, there is a second factor that is now thought to have had a significant contribution to the incident: uncertainty. In a crisis of this magnitude, it is easy for confusion to prevail. Hearts are thumping, blood pressure is rising and people are not sure how to act.

When uncertainty in any situation is high, people are even more likely to turn to those around themand look for cues for appropriate behaviour.

So how does that relate to marketing?

In a recent article we published (link) we discussed The Paradox of Choice, a theory introduced by Barry Schwartz. This theory describes how in the modern age we are constantly overwhelmed by choice (such as having to choose between 272 cereals for breakfast) and that this choice is driving us toward inaction and making us more miserable and helpless.

If you think the sheer variety in shops makes decisions impossible, the competition is even worse online without the constraints of physical space. In shops, and more so online, we feel unsure as to how to make the right choice. As mentioned above, this uncertainty is more likely to drive us to our peers for recommendations and advice.

Recently, I wanted to buy a new product to style my curls. I walked in the shop and looked around. Just looking at the array of options made my hair curlier. There were products for blonde, brown, long, short, frizzy, not frizzy, and then one of each by every brand. I walked out of the shop and decided to first check online which products were the most popular and best-reviewed.

Making a decision any other way was simply too difficult, as I felt I lacked enough information to make an informed purchase.

The Paradox of Choice has made situational uncertainty a permanent condition — smart marketers should take advantage of this by using social proof!

2. Similarity

The next condition which intensifies the effect of social proof is similarity. We are even more likely to copy the behaviour of those who are similar to us. This is because relating to someone makes us pay more attention to what they are doing, in an effort to understand what is the correct thing to do.

Ever wondered why the number of average-man-on-the-street TV testimonials have increased to an unprecedented level? Because they are people just like us.

An experiment by psychologists from Columbia University examined this phenomenon. The researchers placed wallets on the ground in various placed on the streets of Manhattan. They wanted to see what would happen when they were found. The wallets contained $2 in cash and $27 in checks.

In addition, the wallets contained a letter making it clear that the wallet has been lost and found before. The person who had previously found the wallet indicated in the letter that he was happy to help, and returning the wallet made him feel good. What the research changed throughout the different wallets was the origins of the “founder.”

In one case, the letter was written in broken English and was supposedly from a foreigner, and in another condition, it was from a native English speaker, likely an American.

The results were striking. Only 33% of the wallets were returned when the founder was someone foreign — likely dissimilar to the person reading the letter — and 70% of the wallets were returned when the founder wrote in perfect English, likely similar to the person reading the letter.

The characteristics that specifically affect us are age and gender. Numerous studies that have investigated that these traits found them to intensify the effect of social proof.

Murray (1984) conducted a study examining the most effective way to prevent adolescent smoking. In their study they compared four smoking strategies and they effect on minimizing smoking behaviour. They found that teaching specific skills to resist social pressures to begin smoking is indeed effective, however, what they found to be most effective was using same-age peer leaders as teachers.

Appealing our bias to follow the actions of those who are similar to them is no secret to marketers. Just take a look at the following advertisements:




These marketing campaigns make salient the gender similarities and imply that those who identify themselves as similar would benefit from the product.

Moreover, studies done by Dickinger and Mazanec (2008) investigated the main influences on whether a customer makes a hotel booking on sites like They found that the most influential sources for customers were online reviews, in particular those written by friends.

Our friends are those that often we identify closely with and share common traits, values, and characteristics. Therefore, it would make sense that based on the similarity principle, a friend’s suggestion would intensify the effect of social proof.

So what does that mean for marketing?

  • Ever wondered why you see notifications such as this on


This uses not only the technique of social proof but also the one of similarity. It shows what was the “correct” behaviour (in this case, the next purchase) made by people who had a similar interest to yours (bought the same book).

3. Attractiveness

The third principle that significantly influences social proof is attractiveness.

The principle of attractiveness is the simple rule that we are more likely to listen to and comply with people who are attractive compared to ones who are not. Chaiken (1979) aimed to test this hypothesis by conducting an experiment whereby he had students at a university be approached by either someone attractive (condition 1) or unattractive (condition 2) and asked to complete an opinion survey.

The results showed that people were significantly more likely to be persuaded by attractive communicators (both on verbal and behavioral measures of agreement).

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