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About the authors

Dr Noah Goldstein is Associate Professor of Management and Organizations at UCLA Anderson School of Management. He also holds joint appointments at UCLA in the Psychology Department and at the David Geffen School of Medicine. He previously served on the faculty of the University of Chicago Booth School of Business.

Dr Goldstein’s research and writing on persuasion and influence have been published in many of the leading business journals. His work on persuasion featured in the Harvard Business Review 2009 List of Breakthrough Ideas and has regularly appeared in prominent news outlets such as the New York Times, the Wall Street Journal and National Public Radio. In addition to giving keynotes and acting as a consultant for various institutions, Dr Goldstein has served on the Scientific Advisory Boards of two Fortune Global 500 companies.

Steve Martin is an author, business columnist and CEO of INFLUENCE AT WORK (UK), a global training, speaking and consulting company. His work applying behavioural science to business and public policy has appeared in the national and international press, including BBC TV and radio, The Times, the Wall Street Journal, the New York Times, the Harvard Business Review and Time magazine. (He was the guy who penned the original and now world-famous set of tax letters that generated millions of pounds in extra revenue for the UK government.) His business articles are read by over 2.5 million people every month and include the monthly ‘Persuasion’ column in British Airways’ in-flight magazine and regular pieces for the Harvard Business Review.

In addition to his corporate work he is a guest lecturer on Executive Programmes at the London Business School, the London School of Economics and the Judge Business School, University of Cambridge.

Dr Robert Cialdini has spent his entire career researching the science of influence, earning him an international reputation as an expert in the fields of persuasion, compliance and negotiation. He is Regents’ Professor Emeritus of Psychology and Marketing at Arizona State University. His groundbreaking research has been published in the most prestigious scientific journals, as well as being featured on TV and radio and in the business and national press throughout the world. He is the author of the bestselling books Influence and Pre-Suasion.

Dr Cialdini is the President of INFLUENCE AT WORK. In the field of influence and persuasion he is the most cited living social psychologist in the world today.

YES!

60 secrets from the science of persuasion

10th Anniversary Edition

Noah J. Goldstein PhD, Steve J. Martin and Robert B. Cialdini PhD

images

For Jenessa. You’re not my better half. You’re my best nine-tenths. – NJG

For lovely Linds. – SJM

For my grandchildren Hailey, Dawson and Leia. – RBC

This edition published in 2017

First published in Great Britain in 2007 by
Profile Books Ltd
3 Holford Yard
Bevin Way
London WC1X 9HD
www.profilebooks.com

The moral right of the authors has been asserted.

All rights reserved. Without limiting the rights under copyright reserved above, no part of this publication may be reproduced, stored or introduced into a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording or otherwise), without the prior written permission of both the copyright owner and the publisher of this book.

A CIP catalogue record for this book is available from the British Library.

eISBN: 978 1 78283 303 1

Contents

Yes! A decade on…

Introduction

60 secrets from the science of persuasion

1How can you increase your persuasiveness by inconveniencing your audience?

2What shifts the bandwagon effect into another gear?

3What common mistake causes messages to self-destruct?

4When persuasion might backfire, how do you avoid the ‘magnetic middle’?

5When does offering people more make them want less?

6How can offering an option to ‘do nothing’ increase your influence?

7When does a bonus become an onus?

8How can a new superior product mean more sales of an inferior one?

9How can you give your persuasion attempts the X factor?

10When does third beat second?

11Does fear persuade or does it paralyse?

12What can chess teach us about making persuasive moves?

13Which office item can make your influence stick?

14Why should restaurants ditch their baskets of mints?

15How can a favour add flavour to your next business deal?

16What’s the pull of having no strings attached?

17How can you raise the persuasion bar through your CSR?

18Do favours behave like bread or like wine?

19How can a foot in the door lead to great strides?

20How can you become a Jedi master of social influence?

21How can a simple question drastically increase support for you and your ideas?

22What is the active ingredient in lasting commitments?

23What is the key to making multiple goals a reality?

24How can you fight consistency with consistency?

25What persuasion tip can you borrow from Benjamin Franklin?

26Why might it pay to chat on tomorrow’s commute?

27When can asking for a little go a long way?

28Start low or start high? Which will make people buy?

29How can you show off without being labelled a show-off?

30What’s the hidden danger of being the brightest person in the room?

31What can be learnt from captainitis?

32How can the nature of group meetings lead to unnatural disasters?

33Who is the better persuader? Devil’s advocate or true dissenter?

34When can the right way be the wrong way?

35What’s the best way to turn a weakness into a strength?

36Which faults unlock people’s vaults?

37When is it right to admit that you were wrong?

38When should you be pleased that the server is down?

39How can similarities make a difference?

40What tip should we take from those who get them?

41When can snobbery lead to daylight robbery?

42What kind of smile can make the world smile back?

43What can be learnt from the hoarding of tea towels?

44What can you gain from loss?

45Which single word will strengthen your persuasion attempts?

46When might asking for all the reasons be a mistake?

47Ask or tell? What can make your message sell?

48How can the simplicity of a name make it appear more valuable?

49How can rhyme make your influence climb?

50What can batting practice tell us about persuasion?

51How can you gain a head start in the quest for loyalty?

52What can a box of crayons teach us about persuasion?

53How can you stop your audience getting bored after your initial impact has thawed?

54How can you package your message to ensure that it keeps going, and going, and going?

55What object can persuade people to reflect on their values?

56Does being sad make your negotiations bad?

57How can emotion put persuasion in motion?

58What can make people believe everything they read?

59Are tri-meth labs boosting your influence?

60How can you make your ads linger longer?

Influence in the twenty-first century

Ethical influence

Influence in action

INFLUENCE AT WORK

Research notes

Acknowledgements

Index

YES!

A decade on…

Ten years have passed since Yes! was first published and in that relatively short time a lot has happened.

The words ‘Yes we can’ persuaded millions of Americans that ‘Yes they could’, creating a movement that propelled a former community organiser and law school lecturer to the highest office in the land as America’s first black president.*

A revolutionary wave of protests and demonstrations swept across the Middle East, as many citizens, dissatisfied and frustrated by the conduct and rule of their governments, pressed for change.

Europe, too, has witnessed its fair share of events, from the redrawing of borders in the east to devastating terror attacks and mass immigration in the west. And, after a referendum on the UK’s membership of the European Union, the Leave Campaign persuaded UK citizens, to the surprise of many, that it was time to go.

For the global economy much of this past decade has been spent in a prolonged and painful period of recession, with financial markets lurching from turbulence to, sometimes, freefall. Even those emerging nations who initially bucked the trend are now tightening their belts.

Meanwhile, the global population has increased by nearly a billion. And not only is it increasing in size; it is increasing in connectivity too. The last decade has seen the way we access, consume, process and act on information change beyond all recognition. We Tweet. We SnapChat. We update our status on Facebook. We constantly broadcast to our friends (and an even greater number of strangers) what we are up to in our time-scarce lives. In fact time is so precious that we increasingly communicate on the move and in the instant, providing an endless stream of posts via a variety of apps for the benefit of interested others (but mostly advertisers).

Against this backdrop, the study of persuasion science (and the behavioural sciences more generally) has exploded. Researchers all over the world are contributing new insights and understanding into what influences human behaviour, decision-making and conduct. Importantly, many of these scientific advances and insights aren’t just theoretical in nature. They have practical and meaningful implications as well. As a result, governments and businesses alike have willingly embraced them. From selling products to persuading people to pay their taxes, from encouraging pro-social activities to generating millions in commercial returns, the applications of persuasion science (and the related fields of social psychology, behavioural economics and neuromarketing) have moved from being interesting fringe activities to being firmly part of the mainstream.

Given the expansion of ‘new’ advances and insights, coupled with a growing number of books on the subject, readers may be asking themselves why read a book, even in a revised and expanded form, that was first published a decade ago?

Three reasons come to mind.

A lot has happened, but one thing hasn’t changed

Despite the impressive advances that have been documented by behavioural scientists over the past ten years, the fundamental principles of successful influence and persuasion remain the same. While there can be no doubting the significant number of political, societal and technical changes we have witnessed in the last decade, the cognitive hardware we use to process and react to them (our brains, basically) have hardly changed at all. In many ways we share the same processing apparatus as our cousins from previous generations. Sure, we all now own a smartphone (some of us more than one), communicate via multiple platforms and have access to information in an instant, but the fact remains that we are still largely influenced and persuaded in the same ways as citizens from hundreds of years ago.

On Sunday 8 February 1761 London experienced the first of two earthquakes, the second occurring exactly four weeks later. By any modern-day measure the quakes were moderate ones. Both lasted for only a few moments and the damage sustained was largely superficial. Save for a few minor tremors experienced by a small number of people, the earthquakes had little impact on the majority of Londoners.

But for one individual these earthquakes had a major impact.

William Bell was a corporal in the Life Guards Household Cavalry. Bell was convinced that these minor earthquakes were signs of a forthcoming and much larger earthquake that would destroy the city – exactly one month later – and he took it upon himself to be the messenger of this imminent doom. Like a man possessed, he ran from street to street forcefully broadcasting his predictions to anyone who would listen. Despite his efforts, few were swayed. A small number of families began preparations to flee. Most, however, stayed put.

But then something strange happened. As the countdown to the predicted quake neared, a momentum began to develop. Minorities turned into majorities. Those who had originally been on the periphery were now central to the swelling groups of Londoners taking steps to leave the doomed city. Reluctant bystanders, initially paralysed by uncertainty, quickly followed. And then, too, even the sceptics.

The Scottish journalist Charles Mackay would later record their actions in his work Memoirs of Extraordinary Popular Delusions and the Madness of Crowds:

As the awful day approached, the excitement became intense, and great numbers of credulous people resorted to all the villages within a circuit of twenty miles, awaiting the doom of London. Islington, Highgate, Hampstead, Harrow, and Blackheath, were crowded with panic-stricken fugitives, who paid exorbitant prices for accommodation to the housekeepers of these secure retreats. […] As happened during a similar panic in the time of Henry VIII, the fear became contagious, and hundreds who had laughed at the prediction a week before, packed up their goods, when they saw others doing so, and hastened away. The river was thought to be a place of great security, and all the merchant vessels in the port were filled with people, who passed the night between the 4th and 5th on board, expecting every instant to see St Paul’s totter, and the towers of Westminster Abbey rock in the wind and fall amid a cloud of dust.

The day of Bell’s predicted third quake, Sunday 5 April 1761, passed without incident and the following day Londoners returned to the city to resume their lives and direct scorn and anger at the soldier who, a short time afterwards, was incarcerated in a London lunatic asylum.

While a case could be made that Bell’s actions had some initial influence, the primary reason why so many people were persuaded to gather up their families and belongings and leave the city had little to do with his insistent messaging. It wasn’t until Londoners saw some of their neighbours – people just like them – abandoning their homes that they decided to follow. In an uncertain environment, with few cues indicating the right way to act, the action of someone comparable was all that was needed to persuade others to do the same.

It is easy for a twenty-first-century citizen to deride the eighteenth-century Londoners’ failure to recognise that their actions were primarily a result of an unthinking, herd-like instinct, but we would be wise to curb our derision. Despite the plethora of information instantly available at the click of a button or swipe of a screen, today’s modern citizens are just as likely to succumb to such rudimentary influences. It may not cause them to flee their homes, but it can persuade them to flee to a restaurant or cinema. They act not on the recommendation of a food or film critic but on the opinion of a neighbour or peer who is like them. Granted these examples pale in comparison to the London earthquakes of two hundred and fifty years ago. But that’s not to say they don’t happen anymore. If anything they occur more regularly. Since the original publication of Yes! in 2007 there have been no fewer than eleven predictions of catastrophic events that have come to prominence by herd-like behaviours, mostly via the internet. These include the Mayan Apocalypse of 2012 and the End of Time Prophecy of 2016. This last example is especially relevant given that it predicted the end of the world would occur not by an earthquake but by a mega quake, no less.

Few doubt the significant advantages that new technologies and instantly accessible information have brought us. At the same time it we would be wise to remember that the cognitive hardware we use to process this data has remained largely the same. As hard as it might be to admit, we are just as likely to be influenced by the fundamental, but often unrecognised, principles of persuasion as our cousins from 250 years ago.

For reasons of popularity

There is a second reason why readers might be motivated to read an expanded and revised version of this popular book. And that’s because it is popular. At the time of writing this new preface, Yes! has sold over ¾ million copies, been translated into twenty-seven languages and featured in hundreds of newspaper articles, blogs, media features and broadcasts. Businesses and public sector organisations of all kinds have adopted its insights. An online animation has been viewed over 8 million times (and you can see it too by typing ‘science of persuasion’ into any search engine). Rather like those eighteenth-century Londoners uncertain how to act, people reading this with an eye to deciding whether to purchase the book may be interested to know that many others like them already have.

New insights, updated content

The third reason to welcome readers both old and new is that this revised and expanded 10th Anniversary Edition contains updates to some of the original fifty chapters as well as ten additional new chapters, one for each year since the original publication.

The new old

As different as this new book is, we have endeavoured not to tinker too much with what attracted so many readers to the original edition. Each of the new chapters, in addition to the original chapters that we have updated, is still presented in a way that can be quickly and easily accessed. That’s not to say the chapters lack a basis in fact and evidence. Our commitment to presenting only those insights that have been scientifically validated in published research remains unshakeable. Importantly, though, we move quickly from the science of successful persuasion to its practice.

In doing so we hope that both our returning readers and our new ones will benefit from being more persuasive in their professional and personal lives too.

Noah J. Goldstein
Steve J. Martin
Robert B. Cialdini

Footnote

* As we write America is preparing for another transition as a very different kind of President enters office.

Introduction

If all the world’s a stage, then small changes in your lines can have dramatic effects.

There’s an old joke that the comedian Henny Youngman would tell about his previous night’s accommodation: ‘What a hotel! The towels were so big and fluffy that I could hardly close my suitcase.’

Over the last few years, however, the moral dilemma facing hotel guests has changed. These days, the question of whether to remove the towels from their room has been replaced by the question of whether or not to reuse the towels during the course of their stay. With the increasing adoption by hotels of environmental programmes, more and more travellers are being asked to reuse their towels, to help conserve resources, save energy and reduce the amount of detergent-related pollutants released into the environment. In most cases, this request comes in the form of a card placed in guests’ bathrooms.

These cards can provide some remarkable insights into the often-secret science of persuasion. With a nearly limitless array of angles to play and motivational strings to pull, what words should be put on the card to make the request most persuasive to the hotel guests?

Before providing an answer, which we’ll do in the first two chapters, let’s first ask how the designers of the messages on these little cards typically encourage guests to participate in these programmes. A survey of the messages conveyed by dozens of request cards from a wide variety of hotels around the globe reveals that these cards most commonly attempt to encourage towel recycling efforts by focusing guests almost exclusively on the importance of environmental protection. Guests are almost invariably informed that reusing their towels will conserve natural resources and help spare the environment from further depletion and disruption. This information is often accompanied by eye-catching environment-related pictures, ranging from rainbows to raindrops to rainforests…to reindeer, even.

This persuasion strategy generally seems to be effective. For example, one of the largest manufacturers of these signs reports that most hotel guests who have the chance to take part in these programmes do reuse their towels at least once during their stay. The level of participation produced by these signs can be seen as impressive.

Social psychologists, however, are often on the lookout for ways to apply their scientific knowledge to make policies and practices even more effective. Much like a roadside billboard that reads ‘Place your ad here’, these little towel recycling cards speak to us, practically begging us, ‘Test your ideas here.’ So we did. And, as we’ll explain, we showed that by making a small change to the way the request is made, hotel chains can do much, much better.

Of course, how precisely one could go about enhancing the effectiveness of these types of environmental campaigns is but a single issue. Much more broadly, we’re going to claim that everyone’s ability to persuade others can be enhanced by learning persuasion strategies that have been scientifically proved to be successful. As this book will reveal, small, easy changes to our messages can make them vastly more persuasive. We will report on dozens of studies, some conducted by us, some by other scientists, that demonstrate this point in many different settings. Along the way, we will discuss the principles behind these findings. Our central purpose is to provide the reader with a better understanding of the psychological processes underlying how we can influence others to move their attitudes or behaviour in a direction that results in positive outcomes for both parties. As well as presenting a variety of effective and ethical persuasion strategies, we discuss the types of things to watch out for to help you resist both subtle and overt influences on your decision-making.

Importantly, rather than relying on pop psychology or the all-too-common ‘personal experience’, we will discuss the psychology underlying successful social influence strategies in the context of the scientifically rigorous evidence that supports them. We’ll do this by pointing towards a number of mystifying occurrences that can be explained by a greater understanding of the psychology of social influence. For example, why, immediately after the news of the passing of one of the most popular popes in modern history, would hordes of people besiege shops some thousand miles away to buy souvenirs that had nothing to do with the pope, the Vatican or the Catholic Church? We’ll also provide insights into the single office supply that can make your attempts to persuade others significantly more effective, what Luke Skywalker can teach us about leadership, the mistake communicators often make which causes their message to back-fire, how to turn your weaknesses into persuasive strengths and why sometimes seeing yourself – and being seen by others – as an expert can be so dangerous.

Persuasion as science, not art

Persuasion has been studied scientifically for over half a century now. Yet the research on persuasion is something of a secret science, often lying dormant in the pages of academic journals. Considering the large body of research that’s been done on the subject, it might be useful to take a moment to think about why this research is so often overlooked. It’s no surprise that people who are faced with choices about how to influence others will often base their decisions on thinking that’s grounded in fields such as economics, political science and public policy. What’s puzzling, however, is how frequently decision-makers fail to consider established theories and practices in psychology.

One explanation is that, in contrast to how they regard the fields of economics, political science and public policy, which require learning from outsiders to achieve even a minimal level of competence, people believe they already possess an intuitive understanding of psychological principles simply by virtue of living life and interacting with others. As a consequence, they’re less likely to learn and to consult the psychological research when making decisions. This overconfidence leads people to miss golden opportunities to influence people – or worse still, to misuse psychological principles to the detriment of themselves and others.

Besides being overly reliant on their personal experiences, people also rely too much on introspection. For example, why would the marketing practitioners commissioned to design the towel reuse signs focus almost exclusively on the impact of these programmes on the environment? They probably did what any of us would do – they asked themselves, ‘What would motivate me to participate in one of these programmes by recycling my towels?’ By examining their own motives, they would realise that a sign that tapped into their values and identity as an environmentally concerned individual would be particularly motivating. But in doing so, they would also fail to realise how they could increase participation just by changing a few words in their request.

Persuasion is a science. It has often been referred to as an art, but this is an error. Although talented artists can certainly be taught skills to harness their natural abilities, the truly remarkable artist depends upon talent and creativity that no instructor can instil in another person. Fortunately, this isn’t the case with persuasion. Even people who consider themselves persuasion lightweights – people who feel they couldn’t coax a child to play with toys – can learn to become persuasion heavyweights by understanding the psychology of persuasion and by using the strategies that have been scientifically proved to be effective.

Whether you’re a manager, a lawyer, a healthcare worker, a policy-maker, a food server, a salesperson, a teacher or something entirely different, this book is designed to help you become a master persuader. We’ll describe certain techniques that are based on what one of us (Robert Cialdini) explored in the book Influence: Science and Practice as the six universal principles of social influence: reciprocation (we feel obligated to return favours performed for us), authority (we look to experts to show us the way), commitment/consistency (we want to act consistently with our commitments and values), scarcity (the less available the resource, the more we want it), liking (the more we like people, the more we want to say yes to them) and social proof (we look to what others do to guide our behaviour).

We’ll discuss what these principles mean and how they operate in some detail, but we won’t limit ourselves to them. Although the six principles underpin the majority of successful social influence strategies, there are many persuasion techniques that are based on other psychological factors, which we’ll uncover.

We’ll also highlight the way these strategies operate in a number of different contexts, focusing not only on the work-place but also on your personal interactions – for example, as a parent, a neighbour or a friend. The advice we’ll provide will be practical, action-oriented, ethical and easy to follow, and will require very little additional effort or cost to pay big dividends.

With apologies to Henny Youngman, we fully expect that by the time you finish this book your persuasion toolbox will be packed with so many scientifically proved social influence strategies that you’ll hardly be able to close it.

secrets from the science of persuasion

How can you increase your persuasiveness by inconveniencing your audience?

Paid programming, in the form of the ‘infomercial’, is a common tool used by advertisers on the ever growing number of television channels that are available today. Colleen Szot is one of the most successful writers in the paid programming industry. And for good reason: in addition to penning several well-known ‘infomercials’ in the USA, she is the brains behind a programme that shattered a near-twenty-year sales record for a home shopping channel. Although her programmes use many of the elements common to most infomercials, including flashy catchphrases, an unrealistically enthusiastic audience and celebrity endorsements, Szot changed three words in a standard infomercial line which caused a huge increase in the number of people who purchased her product. Even more remarkable, these three words made it clear to potential customers that the process of ordering the product might prove something of a hassle. What were those three words, and how did they send sales through the roof?

Szot changed the all-too-familiar call-to-action line ‘Operators are waiting, please call now’ to ‘If operators are busy, please call again.’ On the face of it, the change appears foolhardy. After all, the message seems to suggest that potential customers might have to waste their time dialling and redialling the number until they finally reach a sales representative. That sceptical view, however, ignores the power of the principle of social proof. In brief, when people are uncertain about a course of action, they tend to look outside themselves and to other people around them to guide what they do.

In the Colleen Szot example, consider the kind of mental image likely to be generated when you hear ‘Operators are waiting’: scores of bored employees filing their nails or clipping coupons while they wait by their silent telephones – an image indicative of low demand and poor sales. Now consider how your perception of the popularity of the product would change if you heard the phrase ‘If operators are busy, please call again.’ Instead of those bored, inactive representatives, you’re probably imagining operators going from call to call without a break.

In the case of the modified line, home viewers followed their perceptions of others’ actions, even though those others were completely anonymous. After all, ‘If the phone lines are busy, then other people like me who are also watching this infomercial are calling too.’

Many classical findings in social psychology demonstrate the power of social proof to influence other people’s actions. To take just one, in an experiment conducted by research scientist Stanley Milgram and colleagues, an assistant of the researchers stopped on a busy New York City pavement and gazed skyward for sixty seconds. Most passers-by simply walked around the man without even glancing to see what he was looking at. When the researchers added four more men to that group of sky gazers, however, the number of passers-by who joined them more than quadrupled.

Although there’s little doubt that other people’s behaviours are a powerful source of social influence, we should point out that when we ask people in our own studies whether other people’s behaviour influences their own, they absolutely insist that it does not. But experimental social psychologists know better. We know that people’s ability to identify the factors that affect their behaviour is surprisingly poor. Perhaps this is one reason why those in the business of creating those little cards to encourage the reuse of towels didn’t think to use the principle of social proof to their advantage. By asking themselves, ‘What would motivate me?’ they might well discount the very real influence that others would have on their behaviour. As a result, they focused all their attention on how reusing the towels would contribute to saving the environment, a motivator that seemed, at least on the surface, to be most relevant to the desired behaviour.

Remember the finding that the majority of hotel guests who encounter the towel reuse signs do actually recycle their towels at least some of the time during their stay? What if we simply informed guests of this fact? Would it have any influence on their participation in the conservation programme? Two of us and another researcher set out to test whether a towel reuse sign conveying this information might actually be more persuasive than a sign widely adopted throughout the hotel industry.

To do so, we created two such signs and, with the cooperation of a hotel manager, placed them in hotel rooms. One sign was designed to reflect the type of basic environmental protection message adopted throughout much of the hotel industry. It asked the guests to help save the environment and to show their respect for nature by participating in the programme. A second sign utilised the social proof information with the honest message that the majority of guests at the hotel recycled their towels at least once during their stay. These signs, as well as some others we’ll discuss later in the book, were randomly assigned to the different rooms in the hotel. Now, typically, experimental social psychologists are fortunate enough to have a team of eager undergraduate research assistants to help collect the data. But, as you might imagine, neither our research assistants nor the guests would have been very pleased to have the researchers sneaking into hotel bathrooms to collect our data, nor would our university’s ethics board (nor our mothers, for that matter). Fortunately, the hotel’s room attendants were kind enough to volunteer to collect the data for us. On the first day in which a particular guest’s room was serviced, they simply recorded whether or not the guest chose to reuse at least one towel.

When we analysed the data, we found that guests who learnt that most other guests had reused their towels (the social proof appeal), which was a message that we’ve never seen employed by even a single hotel, were 26 per cent more likely than those who saw the basic environmental protection message to recycle their towels. That’s a 26 per cent increase in participation relative to the industry standard, which we achieved simply by changing a few words on the sign to convey what others were doing. Not a bad improvement based on a factor that people say has no influence on them at all.

These findings show how being mindful of the power of social proof can pay big dividends in your attempts to persuade others. Of course, the importance of the way you communicate this information should not be understated. Your audience is unlikely to respond favourably to a statement such as ‘Hey, you: be a sheep and join the herd. Baaaaaaaah!’ A more positively framed statement such as ‘Join countless others in helping to save the environment’ is likely to be received much more favourably.

Besides the impact on public policy, social proof can have a major impact in your work life. In addition to touting your top-selling products with impressive statistics that convey their popularity (think of the McDonald’s sign stating ‘Billions and billions served’), you’d do well to remember to always ask for testimonials from satisfied customers and clients. It’s also important to feature those testimonials when you’re presenting to potential clients who may need reassuring about the benefits that your organisation can provide. Or better yet, you can set up a situation in which your current clients have the opportunity to provide first-hand testimonials to prospective clients about how satisfied they are with you and your company. One way to do this is to invite current and potential customers to a luncheon or seminar and arrange the seating plan so that they can easily mix. In this setting, they’re likely to naturally strike up conversations that bring out the advantages of working with your organisation. And if, while taking RSVPs for the luncheon, your potential guests say they’ll have to call you back to let you know, just be sure to tell them that if your phone line is busy they should keep trying…

What shifts the bandwagon effect into another gear?

Our social proof message enhanced guests’ towel reuse compared with the industry standard, so we know that people are motivated to follow the behaviours of others. But this finding poses another question: whose behaviours are people most likely to follow?

For example, would people be more persuaded to reuse their towels by social proof information that conveyed the behaviour of people who previously stayed in their particular room as opposed to the hotel in general? There are some good reasons to expect not. In fact, giving greater credence to the norms of your particular room is irrational for two reasons. First, from a purely logical standpoint, it’s likely that you won’t view the previous occupants of your room in an especially positive light. After all, those are the same people who have, just by staying there previously, played a larger role in reducing the quality of your room and its amenities than any other guests in the hotel. Second, there’s no reason to believe that the behaviours of those previously occupying your room are any more valid than, say, the behaviours of those who stayed next door. Yet, as we discussed earlier, much psychological research shows how people are often wrong about what motivates them to engage in certain behaviour.

If you recall, the social proof message used in the hotel study informed guests that others like themselves – specifically, the majority of other guests who had previously stayed at the hotel – had reused their towels at least once during their stay. We decided to take the perceived similarity one step further by conducting another study in which some hotel guests saw a request to reuse their towels communicating the social proof of guests who had stayed in the same room in which they were staying. So, in addition to the standard environmental protection appeal and the social proof appeal used in the prior study, some guests saw a sign informing them that most of the people who had previously stayed in their particular room participated in the towel reuse programme at some point during their stay.

When we analysed the data, we saw that guests who learnt that the majority of others in their particular room had participated were even more likely to participate than guests who learnt the norms for the hotel in general. And compared to the standard environmental appeal, there was a 33 per cent increase in participation. These results suggest that if Henny Youngman had encountered a sign in his bathroom indicating that not a single person who had previously stayed in his particular room had ever stolen a towel, he probably would have had a much easier time closing his suitcase as he prepared to check out. But why?

It’s usually beneficial for us to follow the behavioural norms associated with the particular environment, situation or circumstances that most closely match our own. For example, when you’re at a public library, do you follow the norms of other library patrons, quietly browsing through the fiction section and occasionally whispering to your friends, or do you follow the norms of the patrons at your favourite bar, crushing books against your forehead for a dare and playing games where you take a drink every time you read a word with the letter ‘e’? If you want to avoid the lifetime ban from the premises that you’d get if the librarian caught you trying to crush that book against your forehead, you’d obviously choose the former rather than the latter.

Earlier, we described the importance of testimonials in trying to sway others’ opinions in your direction. The results of this experiment suggest that the more similar the person giving the testimonial is to the new target audience, the more persuasive the message becomes. This means that in deciding which testimonials to show to a prospect, you need to take your ego out of the process. You should begin not with the one you’re most proud of, but with the one whose circumstances are closest to those of your audience. For instance, a schoolteacher trying to convince a student to come to class more often should solicit comments about the benefits of doing so not from students in the front row, but rather from students who are more similar to the target student.

As another example, if you are selling software to the owner of a string of local beauty salons, she’ll be more influenced by information about how pleased other salon owners are with your software than she will by similar information about the big shots at British Airways. After all, she’s likely to think, ‘If others like me have got good results with this product, then it should be right for me too.’

And if you’re a leader or a manager attempting to persuade employees to embrace a new system, you should ask for a testimonial from others within the same department who have already agreed to make the switch. But what if you’ve tried that, yet you still have one stubborn employee – perhaps the person who has been working with the older system the longest – whom you can’t win over? A common mistake managers might make in such a case would be to choose the most eloquent coworker to try to explain the benefits to his or her stubborn colleague, even if he or she is completely different from that person in a number of important ways. Instead, the manager’s best bet would probably be to solicit the opinions of a similar co-worker – perhaps someone else who had also been working under the system for a long time – even if that person happened to be somewhat less articulate or popular.

A few months after the first edition of Yes! was published, one of us received a call from HM Revenue & Customs with an interesting question. Would the approach that had persuaded so many people to reuse their towels in a hotel have a similar effect when encouraging people to submit their tax returns? Several months later the answer appeared to be yes. Standard letters that focused the recipient’s attention on the penalties for not paying taxes on time were revised and a single sentence added prominently at the top. That sentence truthfully pointed out that most people in the UK do pay their taxes on time. The impact was both impressive and immediate: a 5 percentage point increase in return rates. We then wrote a second letter referring not to the majority of people in the UK who paid their taxes on time but to the large number of people living in the same postcode who did. This letter increased tax returns by some 12 percentage points. The letters, together with a variety of others subsequently developed by the UK’s Behavioural Insight Team, have helped collect hundreds of millions of pounds as a result of additional revenue and cost savings.

From this experiment, a puzzling question emerges. Given that the UK, like most countries, had been interested in identifying effective methods of collecting taxes for centuries, why had such a simple and costless strategy not been considered before? Like most professionals working in complex and specialised environments, UK tax officials probably thought that the answers to their challenges would lie in the activities of those most like them: in this case, the best practices in the tax systems of other countries. As a result it is easy to see how the idea to include a social proof message in the form of an extra sentence on letters would have been missed. Even if such an idea had been considered, it is possible that it would have quickly been dismissed. In hindsight, and maybe due to the influence of books like Yes!, we know more than ever about the incredible impact that others’ behaviour can have on our own.

We are certainly not dismissing the value in sharing best practices between organisations. But we would urge caution if that is the only place you look.