– A Global Marketing Group Company

The Psychology of Social Proof and Why It Makes Word-of-Mouth Marketing So Effective

Let’s Start from the Beginning: What is Social Proof?

Social proof is a result of a deeply rooted psychological bias. It implies trust in other people. The forms of this trust include the belief that the majority knows better and that the best way to make a decision is to look at people and see which decision they’ve made. As most psychological biases, this one generally makes sense.

Think of your behavior in any new environment: at a new workplace, or at a party where you don’t know anyone, or in a foreign country. Every reasonable person will first observe what others do before making any decisions regarding their own behavior. In the end, this is how evolution taught us to think. Humans that would appear in a new tribe and talk and dance without figuring out the language and rules of politeness were killed first.

And yet, relying on the behavior of others is a mental shortcut. We’re supposed to take the behavior of other people as a clue as opposed to a certain proof that the behavior is correct. But often, we see others and we simply copy their ways, ignoring or devaluing other clues.

The bias works best when we’re uncertain in what to do, when we’re in a happy mood, and when there are a lot of other people that seem similar to us. The huge effect of social proof has been shown in various different activities. From donating money to charity to engaging in “safe” or “unsafe” behavior, people would rely on others to show them what’s right, regardless of their own knowledge.

Social Proof is a Gift for Marketers

Obviously, social proof is a gift for marketers. And incidentally, this bias is exactly why word of mouth is such a powerful thing. If people even copy others’ risks, how could they resist copying others’ product choices?

Word of Mouth

Imagine you see a well-crafted ad that tells you about the benefits of the product you’ve always wanted from brand A. The ad has stats, proof, and a scientific explanation of why it’s a good product. Basically, it’s not your usual eye-grabbing senseless ad — it’s a truly good explanation why the product is worth it. Then, imagine your colleague tells you out of nowhere: “Oh you know, I just bought product B, it’s so amazing! My hair/knowledge of Chinese/life has been completely changed since then!”

Which one, do you think, will get stuck in your head? Which brand, A or B, would you choose?

If you’re not sure, I’ll tell you: brand B.

Word of mouth is extremely powerful. It derives from the same principle of social proof — you see a real person, someone you know even, you trust they know what they’re doing. Then imagine how this is amplified if you hear not one, but a couple of people you know talking about brand B! Or, alternatively, your colleague and also a random Instagram user that you follow for no particular reason. The effect is comparable to a geometric progression.

Employing social proof is a fantastic way to leverage word of mouth. Let’s look at 4 types of social proof, and how we can leverage it.

1. Expert Social Proof

While some believe that “we’ve had enough of experts”, generally people still trust those who are considered experts more than those who are not. This sounds reasonable, at least. This is why you’ll see doctors in healthcare-related ads, sportsmen in sportswear ads, and all sorts of science-related people in the ads for electronics, heavy equipment, medicine, and everything in between. While we might look at the ad and not remember any other info, we’ll most likely remember that it was backed by an expert and pass this information along in a relevant context.

2. Celebrity Social Proof

Weirdly enough, people talk a lot about celebrities. They discuss their love life, lifestyle, fashion, and everything associated with them. It’s puzzling, but there’s no doubt the interest of most people in celebrities isn’t decreasing with time. 

There’s a reason celebrities’ posts on social media are extremely expensive — that’s because a mention of a product from a celebrity doesn’t only reach a huge amount of people, it also starts off a discussion where people share with others the information on which body lotion their favorite model uses. The reach keeps snowballing, and the social proof grows. 

However, I’m sure you see a problem: celebrity marketing is ridiculously expensive. Luckily, we don’t always need a football player or an actress doing the job. For most products, micro-influencers -—people that are famous on social media — will do the trick, as long as they have a substantial following (10k-100k) and a good engagement rate, with the latter being far more important. 

Celebrity Social Proof

3. User Social Proof

The importance of user social proof becomes clear the moment you open any trendy website. You might not see product descriptions or prices, but you will see social proof in all its forms. There will be a list of companies that have used the product (if it’s B2B), a list of user testimonials (in all cases), reviews or a proud note that the product or service has been reviewed on G2 Crowd, or TripAdvisor, or Yelp. Websites where users can leave reviews and buy the product have been most successful. Basically, people love reviews – it’s their online access to word of mouth. 

It’s especially interesting that people don’t seem to often even care which kind of reviews are those. Counterintuitively, research shows that when it comes to reviews, it’s the quantity that counts. How many people have used the product. The size of the social proof is enough (or too overwhelming?) for people to look into details. They simply do what others have already done – buy the product. 

User social proof isn’t only in reviews and testimonials, it’s also in social media following. Buying social followers is a very arguable practice: the algorithms of social media platforms are made so that purchasing fake accounts might hurt the reputation of your social account. However, growing a following is important in terms of growing social proof: the more people show that they use the product, the more others accept that the product is a good one automatically, without giving it another thought, and even share this information further.

4. Friends’ Social Proof

The most powerful social proof in terms of its effect on the word of mouth is social proof that comes from friends. We trust information that’s shared by people we know, we share this information further with much excitement. And as it usually happens, it’s hard for marketers to do anything with this knowledge. Friends’ social proof is very hard to achieve in any semi-authentic way. You generally just make a good product and hope people will pass the information along. Some companies, such as Uber and AirBnB, offer discounts for friends, which is a neat thing to do as it plays on both social proof and a wish of a usual person to get a discount. 

The other way in which marketers have successfully employed friends’ social proof is through showing which Facebook friends or email contacts are using the service. The list is shown to you when you register at websites like Couchsurfing or LinkedIn. It also works for online services that show you which ones of your online friends are using the service. For example, in a study on online security, it was found that showing the users that their friends are using the online security feature is the most effective persuasion method. 


Social proof and word of mouth are connected concepts. It’s very hard to achieve the ever-growing word of mouth without putting some effort in growing social proof. Go ahead, experiment, work with influencers, and, most importantly, work on creating a product — and a talk trigger — that’s worth talking about.

Original Source