Part Five – Jumping Off A Bridge

By: Ilan Mann

April 18, 2020

This is part five of an ongoing series about consumer behaviour. You are strongly encouraged to read at least part one here and part two here before reading this post. You can also read part three here and part four here.


System one and system two evolved for reasons that may not appear obvious to us, but are apparently deeply rooted in what it took to survive for most of human history.

System 2 can develop theories around the best way to build a fire, or structure a tribe, or calculate the strength of the sail need to the get to that island over there (though when actually doing sailing, system 1 is probably in control). Think Spock from Star Trek.

System 1 – instinct, intuition, feelings – can tell us from a distant sound that there is danger nearby, or give us a bad feeling about the way that stranger is looking at us, all based on thousands of calculations happening rapidly in our subconscious. We start running away from the danger before we really know what the danger is. Think about Spiderman’s spidey-sense (though at least one Spiderman nerd whom I consulted insists that this is not quite accurate).

Imagine yourself in a setting where you feel comfortable, but there are plenty of other people around. Maybe it’s a restaurant that you like, a busy strip downtown, or a shopping mall in your town.

Suddenly, you sense danger. For anyone who has every been in this situation, you know that you sense danger before you can pinpoint why you sense danger; it’s almost as though you’re in a movie, and the music changes to something ominous. Before there is an obvious indication that there is danger (a crash, a scream, or a menacing figure) there is often a subtle change in the behaviour of those around you. Someone near you has adopted a concerned expression, because someone near them has turned to look over their shoulder, because they picked up on the absence of sound emanating from that now-silent formerly-loud group of teenagers. The reason for that sudden silence is that one of the teenagers saw something across the mall (or intersection or restaurant) and the others noticed a change in their tone and mirrored it. What they saw was someone running away from something. Someone who had seen or heard something that made them run faster than their brain could fully process the fact that what they had seen or heard was dangerous, but who intuited it just the same.

Human beings are social animals, and our brains evolved to enable us to survive in tribes, communities, cities, and civilizations. We are highly attuned to the behaviour of others around us, and often use their behaviour as cues for our own.

That’s why we find it so difficult to be contrarian, even when there is little or no evidence to suggest that there is wisdom in what those around us are doing. System 2 may be the rational of the two, but it is anything but robotic or slavish. System 2 is creative, and thoughtful, and can be contrarian by choice.

Take this awesome 1962 social experiment from candid camera, for example:

So how do you, the clever and enterprising marketer, take advantage of social proof in your handwritten cards & letters, and other direct mail marketing?

Since everyone around me seems to be blogging in list form, I may as well (see what I did there?) Here are the top 4 ways to use social proof in your direct mail marketing:


Use a user testimonial

Particularly if the product that you’re selling or service that you’re marketing is new, novel, or non-intuitive as a value proposition, one of the first things that customers, donors, etc… look for is a testimonial.

They don’t want to be the first one to jump off of the bridge – they want to make sure that at least one person has already jumped, survived, and thrived.


Use the scarcity heuristic to create a fear of missing out

They may not want to be the first one to jump off a bridge, but they certainly don’t want to be the last one. Convey a sense of popularity (social proof) but also a sense of urgency. This is known as the scarcity heuristic, and like the effort heuristic (discussed in the last part of this series here), it persuades people to assign value based on a mental shortcut. Just like consumers ascribe more value to products and services that seem to be a result of more effort, they also ascribe more value to products and services that seem scarce.

LIMITED TIME OFFER may be cliche, but it’s also powerful.

“We don’t want our space to get too crowded, so we are offering only 25 residents of Woodlawn towers premium, unlimited access to our gym and health club, with concierge service, and 21 of your neighbours have already signed up. Jenny, who lives in Woodlawn tower 2, said that she has never had a better spa experience.”


B.Y.O.S.P (Bring your own social proof) 

You may not remember this, now that the platform is so ubiquitous, but Gmail started out as a very limited service, that you had to be invited to by a friend.

Users received 5 invitations that they could give out (there’s that scarcity again), and so every person who signed up for the platform was referred to the platform. Rather than being marketed to, they were invited.


That’s a strong social proof – you are being given one of 5 invitations from a direct friend who uses the product and tells you that they should too.

Think about how you can achieve the same result with your next variable mailing. Some of our non-profit clients achieve this result by having different relationship managers or volunteer canvassers sign solicitations that are going out to people in their network.

Splitting donor lists in that way may be a difficult endeavour, but social proof experiment after experiment proves that it’s worth the effort in the increase in conversion rates.


Make your product exclusive to an existing club

When Facebook started, there was only one way to sign up for an account. Your email address had to end in Soon they expanded to other schools, but the principle remained consistent: you had to have an email address ending with the domain of an approved college or university to sign up for an account.

By leveraging an existing social group ( or Facebook was able to imply a social proof that may or not have actually been there. Once Facebook is available to, the inference is that others – maybe almost everybody – at Florida State University is using this product; otherwise, why would the company need to go to the trouble of making a separate facebook access point for FSU?

A better example may be university foundations that create specific campaigns for different subsets of their alumni. Don’t just donate to the school’s endowment, donate as part of the Class of 2015 class gift. Or the Class of 2015 5-year reunion gift.

In fact, my own school told our graduating class that their goal was not to raise a certain amount, but rather to get 100% participation. They were using a few powerful consumer behaviour tactics (not unusual for the business school perhaps most famous for behavioural economics research), amongst them the tactic of increasing social proof – if their goal is 100% participation, I implicitly believe that they have a realistic chance of reaching it, which is to say that almost everyone else in my class is already jumping off that bridge.

United way is a great example of a charity that uses this tactic to ramp up social pressure on a group. Rather than asking every lawyer in Toronto to donate to their annual campaign, for example, they will create mini-campaigns for each law firm, and publicly track the total given by that firm. Without disclosing participation rates, they publicly imply that giving is a widespread phenomenon, across your firm and across your industry.

Increasing social proof is one of the most effective ways to pack a punch in your next handwritten mail campaign. It appeals to something deeply rooted in the human psyche, and it works.


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