Social proof: Everyone else is doing it.

Accompanied by two of your friends, you find yourself standing in a gelato store. You feel slightly overwhelmed by the number of gourmet flavours so you turn to your friend and ask “What are you getting?”. She replies that she has never tried any of these flavours before, but has settled on ‘cookies and cream’. Your second friend pipes up and says that he has decided to order ‘turkish delight’. Unsure of which option will be better, you notice that the woman in front of you has ordered ‘turkish delight’ too. You feel a wave of calm come over you as you step forward and say to the man behind the counter, “I’ll have what she’s having”.

You may have found yourself in this typical “I’ll have what she’s having” situation before. It is not uncommon to rely on the behaviours of others when making decisions in uncertain situations. Human beings are, after all, herd animals and we often make choices by validating that others are following a similar course of action. This is especially true in cases where we consider the people around us to be similar to ourselves. This kind of social influence is known as social proof, which is a psychological and social phenomenon where people assume the actions of others in an attempt to reflect the correct behavior in a given situation.

An experiment into the power of social proof was conducted using pretzel sellers on trains. In the control group, the pretzel trolley was wheeled up and down the train carriages. One in twelve people bought pretzels in this group. In a second experiment, people eating pretzels were instructed to walk through the carriages before the pretzel trolley arrived. In this case, one in seven people bought pretzels. In the final experiment, pretzel eating stooges were planted besides passengers while the pretzel trolley passed. In this scenario, one in six people bought pretzels.

While buying a pretzel or two may seem pretty harmless (other than its effects on your waistline), social proof can be problematic for two main reasons. Firstly, groups of people can reach conclusions which are suboptimal or even outright wrong. This is also known as groupthink or herd behaviour. Secondly, social proof can lead to inaction, known as the bystander effect, even in extreme cases such as an individual having a heart attack.

Another drawback of social proof, and one that marketers should be particularly aware of, is negative social proof. A classic example of negative social proof occurred in the Arizona Petrified Forest. The theft of unusual petrified wood by visitors was becoming a serious issue as it depleted the ancient woodland. Staff put up a sign stating: ‘Many past visitors have removed the petrified wood from the park, destroying the natural state of the Petrified Forest.’ This was intended to deter theft, but it had the opposite effect. The depletion of the petrified wood tripled. Experts who looked at the case determined that the signs had served as social proof by making visitors feel that the act was justified, because ‘everyone else was doing it’.

Now, you may be wondering how to avoid the pitfalls of social proof. The strategies largely depend on the context in which it occurs. In cases such as advertising, you should ask yourself whether the “average people” in the advertisement are real customers or just paid actors (and it’s often as easy as reading the fine print). However, in more serious situations like a medical emergency in a crowded public area, you should remove ambiguity to combat social proof which, in this case, will take the shape of the bystander effect. According to Robert Cialdini, author of Influence: Science and Practice, you can remove ambiguity by pointing to someone specific and saying, “You there in the blue shirt! I’m having [medical emergency]. Please call an ambulance”. Don’t worry about seeming rude, because in these situations it is crucial to be direct, or you could risk social proof working against you if the situation is left too ambiguous. That being said, the effects of social proof are not always negative as it can result in life saving actions, like moving away from a dangerous flooding area because you observe others fleeing before the flood has even reached you.

Clearly, social proof is a powerful tool for persuasion. However, once you can identify and review social proof with a sense of detachment, you can observe its effects on your decisions as well as on those around you. In this way, you could use social proof as a tool for choosing a course of action (or at least that’s what you can tell yourself while you order the turkish delight flavoured gelato anyway).

Read more about social proof:

I’ll have what she’s having by Alex Bentley, Mark Earls and Michael J. O’Brien

Influence: Science and Practice by Robert Cialdini or his six principles of persuasion here.

Read more about using social proof to increase tipping in our experiment here.

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