9 Out Of 10 People Agree – Social Proof Works


However independent we think we are, we’re pretty needy at heart. So, whenever we’re not sure what we should do next in a given situation, we tend to look to those around us to guide our decisions.

In the 1960s, social psychologists Stanley Milgram, Leonard Bickman and Lawrence Berkowitz conducted an experiment in the middle of New York to prove the power of social proof. It was a pretty straightforward setup. A man walking down the busy pavement would simply stop and look upwards for 60 seconds. The psychologists would then observe the effect on people walking past the actor while he held this position.

What they found was that about 4% of people walking by stopped and looked up too. The actor made a difference, but not a very big difference.

So, they expanded the variable – they added four more upwards-looking actors to the experiment. And what they found was that when five people were staring at the sky instead of just one, 18% of passers-by followed suit. The additional social proof was over 400% more persuasive.

Online, we see social proof used in a variety of different ways every day. Here are just a few of the ways social proof is being used to influence our decisions around brands and products.

Bestselling Products

The bestseller list is perhaps the granddaddy of social proof – lots of other people have bought this item, so you probably should too.


Source: Waterstones

Many websites and physical stores use this technique, but the reason I like approaches like Waterstones’ is that segmented bestseller lists are a great way to inform future personalisation when a new visitor has landed on a site.

Let’s say a landing page includes different placements focusing on the most popular books for travel fans, sports obsessives and so on. Based on the category the user clicks on, Waterstones now have a clear idea of what kind of content that person might benefit from next time they land on their site and can potentially tailor the experience accordingly.

‘People who viewed this went on to buy that’

It can be tricky for websites to get this one right. On a product detail page, you don’t want to distract users from the item they’re already browsing by making them consider a different product. However, if they’ve already decided the current dog shirt they’re viewing isn’t for them, you don’t want them to have to go back up the funnel to find a suitable alternative.

social proof

Source: Amazon

AB testing can be a good way to find the best average place for a component like this within your product pages.

Bundles and ‘Typically bought with…’ placements are the spiritual cousin of this technique, assisting in basket building without taking users off path. The key here is to create no brainers. If the user has to learn a lot more about the other products in the bundle, you risk them going cold and losing them altogether.


It’s no secret – when famous people are seen to endorse a product, that product tends to sell. In many ways, a celebrity’s face has the same trust-building abilities as an anti-virus badge on a checkout page, or a Cannes Festival logo on a film poster.

This continues to shift into new areas with the rise of the internet. Sportspeople and film stars are still probably as aspirational as they ever were, but in recent years, social media superstars have exploded in influence and accessibility to reach the same level of idolisation.

At VidCon 2015, YouTube CEO Susan Wojcicki revealed research that indicated 62% of 18-24-year-olds in the USA would buy a product endorsed by a YouTuber.

So, since WHSmith launched their Zoella Book Club in 2016 – a collaboration with popular YouTuber Zoe Sugg, aka Zoella – it’s not surprising to see that two of Zoella’s selected book bundles currently sit in the top 8 of WHSmith’s children’s bestseller list, along with two of Zoella’s own books.

social proof

Source: WH Smith

Reviews and Star Ratings

Amazon users say star ratings and reviews from their fellow customers are the most important part of the company’s product pages, and user-generated questions and answers aren’t far behind. And those pieces of content get even more attention (and end up bringing in a lot of traffic) when they happen to go viral.

social proof

Source: Amazon

Many companies now allow users to filter reviews for those more relevant to them. If I’m just starting out as a jogger, I don’t need the shoes that get five-star ratings from Usain Bolt. I need to know that they’re going to protect my joints, and whether they’ve helped other slobs get into jogging.

Another slightly different use of customer reviews is the way middleman companies like eBay, Airbnb and BlaBlaCar offer a dynamic where both parties involved in the transaction review one another – buyers and sellers, hosts and guests, drivers and riders – sort of like an eCommerce version of the Black Mirror episode ‘Nosedive’.

social proof

Source: Airbnb

I stayed in an Airbnb property for the first time last summer and it’s the tidiest I’ve ever left somewhere I’ve stayed (including my own house). I think that’s because I knew preserving my good Airbnb rating would make other hosts on the site more likely to accept my booking requests in the future.

Likewise, if I owned an Airbnb property and wanted to make sure I continued to receive a good amount of bookings in my holiday rental property, I may not be too scathing about people who stayed there in case it attracted reciprocal negative feedback on my own profile.

While TripAdvisor reviews are pretty much a one-way process and can make or break a business, the likes of Airbnb have grown thanks in part to a dynamic which encourages all parties to act politely before, during and after the transaction.

Implicit Popularity

Booking.com makes a great job of showing how many people are looking at a particular hotel at that moment in time, or how many rooms are left for a given date – this is great for social proof as well as scarcity, another key element in the persuasion equation.

social proof

Source: Booking.com

And the National Lottery site used to take this a step further, sending notifications to website visitors along the lines of ‘Harry M in Chester just won £10!’, using a more personal (and local) experience to encourage users to join and play their online games.

Social proof isn’t a new concept. In fact, when it comes to selling things it may well be the oldest trick in the book. But when you get it right, and keep getting it right as new trends and technologies emerge, it has a very powerful effect. Trust me, seven other people have said the same thing recently.

Our CRO team are experts in online behaviour, pre-empting how your customers shop. If you want to get in touch and identify how your website could be optimised for greater conversion rates, drop us a line at office@banc.digital

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Anita Pun