Blood, biceps and bad reviews: a short history of social proof

Humans are more inclined to do something when they see other people doing it. It’s innate. Hardwired into us since our caveman days of hunting and being hunted. If your neighbours come sprinting past your home, spears in hand, chances are you should be joining them. They know something you don’t, and copying them might just save your life.

We call this social proof. And while a few thousand years ago, our innate desperation to follow the crowd kept us alive – today it drives culture, fashion, and yes: advertising.

The truth is, wherever there’s an inborn, predictable human reaction to something, there’s an opportunity for marketers to manipulate it. And marketers have been taking advantage of social proof for millennia.

AD 79: “All the late drinkers ask you to vote for Vatia”

One of our earliest examples of social proof in action comes from first-century Pompeii. The very unhappy circumstances of the volcanic eruption in AD 79 had the happier upside of preserving much of city life, including the election notices of municipal campaigners before the eruption.

One carefully positioned mural – beside a tavern – reads:

Marcum Cerrinium Vatiam aedilem oro vos faciatis seribibi universi rogant

or:

All the late drinkers ask you to elect Marcus Cerrinius Vatia aedile.

Not only is this a good, though rudimentary, use of social proof; it’s also an example of great media placement, for any visitor to the tavern next-door is more likely to feel aligned to their likeminded ‘late drinkers’ than the population at large. And if they’re voting for Vatia, you should too.

Which gives us our first lesson in social proof: the more socially aligned your audience is with the ‘crowd’ you’re referencing, the more likely they are to follow.

1180: “The people narrate the mighty work of the saint”

Picture this: you’ve been blinded and castrated as punishment for a drunken brawl, but after a meeting with Thomas Becket (and a suitable show of repentance), you make a miraculous recovery, and your wounded body parts grow back.

Such miracles happen less these days, but the tale of Eilward of Westoning is one of many depicted in Canterbury Cathedral’s stained-glass windows. These stories of incredible recovery – from healing lepers to regrowing genitals – were the Cathedral’s contemporary interpretation of what today we might call a ‘testimonial’.

As pilgrims arrived from far and wide to visit the shrine of Thomas Becket, they were offered souvenir flasks of Becket’s blood to restore them and send them on their way. Was it truly blood or merely water? And was it really worth the steep expense? Tourists need only look up at the stained-glass testimonials to know the answer.

This leads to our second lesson in social proof: if you have evidence of others using and benefiting from your product – and even better, if you can get them to tell their story directly – let them do the talking.

1901: “Prizes will go to those whose development is most symmetrical and even”

By the nineteenth and early twentieth centuries, advertising techniques had become a touch more sophisticated. We might even argue that one of the earliest examples of a true social influencer materialised in the guise of Eugen Sandow in the 1890 s.

A frankly frightening Prussian man with a penchant for bodybuilding, Sandow built a fitness empire out of middle-class Britain. Sandow’s magazine of Physical Culture capitalised on a newly redundant class of people who found themselves wealthier, freer, and a little bit fatter after industrialisation.

While his magazine shared tips and tricks for body sculpting, Sandow’s true genius came in generating audience participation. In 1898 he launched ‘The Great Competition’, inviting readers to submit photos of their bodybuilding progress for judging. Regional winners received gold medals, and in turn had their photos featured in the magazine. So if any sceptical readers were having doubt about their ribcage expansions, the evidence was right there in front of them.

Giving us our third lesson in social proof: through competition, promotion or coercion, get your audiences to try it, and create a mechanism for them to shout about it.

1946: “More doctors smoke Camels than any other cigarette”

Using social proof can also be irresponsible. Through the early and mid-twentieth century, health concerns about smoking were growing. While the science was catching up and advertising standards were nowhere to be seen, the R.J. Reynolds Tobacco Company stepped in with an incredibly misleading – but to be fair quite clever – campaign.

More doctors smoke Camels than any other cigarette.

And indeed it was true. When the company’s ad agency, William Esty, met with 113,597 doctors, offered them a pack of Camels, and then asked which brand they smoked – they invariably said Camel.

The witnesses were led, but their testimony stood, and the message was clear: if doctors are smoking this brand, you needn’t worry about those pesky health concerns.

So our fourth lesson in social proof is thus: using people with authority in your industry adds to the weight of social proof. (Just make sure you do it responsibly.)

2026: “Kinda smells like expired hotel shampoo”

Two thousand years of marketing wisdom gives us a clear formula for social proof: find a crowd, get them to say good things, and shout about it. So when Dove launched a campaign for its Intensive Repair Serum Hair Mask this year, its approach raised eyebrows.

Asking Reddit for candid thoughts and feedback on the product (a dangerous community to provoke on any matter), Dove promised to publish the first 50 reviews, good or bad. And they really did. Among the praise on its New York billboards sat stinkers like:

Smells hella bad.

Why? Partly because it was a recipe for a Cannes Lions Award. But mainly because it screamed authenticity in a world where consumer trust is low. Let’s face it, consumers have good reason not to take advertising at face value, so a campaign with negatives sprinkled among the positives only strengthens trust in the latter.

Which brings us to our fifth and final lesson in social proof: a controlled number of bad reviews can give more credibility to your good ones.

The techniques may have become more sophisticated, but it's clear that social proof remains as central to marketers now as it was two thousand years ago. But it's only one tool in the box. On 7 October, we'll dig into the wider Theory of Behaviour Change, looking at loss aversion, scarcity and more, and how today’s marketers can put them to work. Lots of people are already coming. You should too.