Social proof is one of the most well-known psychological concepts in marketing. Popularised by Robert Cialdini as the force behind persuasion and influence, it’s been talked about by every sales guru. The rise of social media marketing, the phenomenon of fake users, the unprecedented success of influencer marketing - all have been attributed to the power of social proof. So let’s not stay behind, and talk about the phenomenon of social proof. 

Social proof means we use other people to determine what is correct.

We copy behaviors of other people and follow the majority. Like all psychological heuristics, this one is not ungrounded: very often the best way to judge an appropriate behavior is by looking at how others behave. It’s an evolutionary mechanism. However, it’s still a mental shortcut. In a perfect world, you’d look at how others behave, process the information through your own knowledge and experience, and then produce an emotionally unaffected result. In reality, people often stop at the first step, even when the decision is against their own best interest. This is mostly prevalent when people are uncertain in a given situation, show a collectivistic approach to life (as opposed to individualistic, i.e. prioritising social goals over personal goals) and live in a collectivistic society (e.g., Poland as opposed to U.S.). Also, like many other cognitive biases, it’s likely to work best when the person is in a happy mood.

The effect of social proof has been shown in situations such as returning a lost wallet, littering in a public place, donating funds to charity, approaching a frightening dog, engaging in promiscuous sexual activity in a “safe” versus “unsafe” manner, and many others (source). It’s been shown to sometimes lead to some strange and horrible consequences. Early social psychologists, such as Asch, showed that subjects copied the mistaken evaluations made by others, even though the right answers were clear as day. In a famous study of bystander apathy, researchers showed that bystanders in a group were less likely to help in an emergency than if they were alone. If they saw that others wouldn’t perform any actions, they would conclude that the actions should not be performed. There were a couple of scandalous real-life cases when this was exactly the case. Even incomprehensible events like mass suicide at Jonestown have been explained by social proof. 

Social proof works best when the proof is provided by the actions of a lot of other people that are similar to you.

The volume of social proof is very important: some studies showed that the amount of reviews affects the sales while the reviews themselves - not that much. Seems like potential customers are overwhelmed by the fact that so many other people bought the product, and follow the lead without looking closely or even at all. Similarly, the laugh tracks you hear on sitcoms aren’t there to annoy you: loads of studies showed that viewers perceive the jokes as funnier when accompanied by a laugh track. You’d think that such deep emotions as humor wouldn’t be affected, but even the perceived pain and expression of fear are heightened when socially confirmed (source). 

The similarity is the second most important thing in the effectiveness of social proof. In a study on charity donations, phrases such as “students like you have been donating about $3 to $5 dollars” and ‘‘people who live in the neighborhoods like this are likely to help’’ were the most effective in driving donations. They were proven to be even more successful than widely used phrases such as “every penny helps”. In a study where researchers aimed to promote and increase the use of online security, they found that simply showing the users that their friends are using the feature is the most effective method. In this case, 37% more viewers explored the promoted security features compared to the non-social (raising awareness) announcement. 

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Social proof (similarly to other biases) works best under a state of low self-control. Usually, this works against the person, but it could also work to, for example, promote healthier purchases. In a study, a healthy low-fat cheese was promoted with banners stating it was the most sold cheese in that supermarket. Customers low in self-control (it was experimentally induced and compared to a high self-control condition) were more likely to buy the low-fat cheese when the banner was there. 

Considering this powerful effect, it’s no surprise marketers don’t spend time coming up with logical arguments, statistics, and competitor comparisons to prove that their product is the best one. Instead, they use different kinds of social proof, first broken down on TechCrunch

1. Expert social proof

Expertise isn’t necessary for social proof to work. However, we generally trust experts more, which is a logical thing to do. Therefore, it makes sense to have a mix of both when selling your product. You’ll often find that companies include a list of other famous companies that use their product on the homepage. Very little information is often displayed on the homepage, but this one will always be there. 

2. Celebrity social proof

Celebrity endorsements are still a huge thing: just look at the prices for a promotional social media post from celebrities. However, the biggest reason for these prices is their reach, not their influence on people’s decision-making (although, of course, this one is also huge). Besides, more and more advertisers focus on niche online influencers as opposed to huge celebrities with the biggest reach. In both cases, however, social proof is in their personas. People see the number of likes the promotional post gets, and assume it must be something people genuinely endorse, even when they might be aware that social media reactions are often meaningless.

3. User social proof

User social proof is also used on all quality home pages. Getting testimonials, asking customers to leave a review on Google, Amazon, or specialized review websites, sharing positive review on social media pages - all these efforts are very much effective. As you should remember from the study above - it’s the quantity that counts in this case. 

4. “Wisdom of the crowds” social proof

Since the ancient times we’re certain that the majority is right. We’ve made a political system based on this notion. It’s the idea that underlines so much of our beliefs and behaviors. Why then not say it how it is? 
Advertisers of all times love slogans that imply that “a million people can’t be wrong”. That’s why it’s necessary to point out the general popularity of your company, of a particular product, and so on, for example, letting the customers know when you hit your million’s buyer or what’s your best selling product each week.

5. “Wisdom of your friends” social proof

As much as we trust the crowds of strangers, we obviously trust our friends more - even if they are no experts in a given topic. That is why when you start using sites you haven’t used before (e.g., Couchsurfing, AirBnB, TripAdviser, etc.) they’ll show you which ones of your Facebook friends already use the site. This facilitates trust and proves that the product or service is popular among your friends. 

Building your own social proof isn’t an easy task. It requires growing online following, working with social media influencers, growing word-of-mouth, brand reputation and brand awareness. However, let me say this: it’s so much easier now that we have social media and a myriad of ways to work with it.