I was sitting in a car outside Marks & Spencer in Camden when I realised that Professor Robert Cialdini had completely changed my way of looking at the world.

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There I was, waiting for my wife to emerge from the exit with some shopping, and all the while watching a man selling copies of The Big Issue to people going into the shop’s entrance. Or at least, trying to sell copies. He wasn’t having much luck. People were sweeping past him.

Now the thing about the doors at M&S – as anyone who has popped in to spend almost £10 on some cherries, then come to their senses, will know – is that you can’t go out of the “in” doors. But then one lady shopper tried to do exactly that. And Big Issue man was kind enough to push the door open from his side.

At that moment I knew what would happen next. Absolutely knew it. And it did. The lady shopper bought a copy of The Big Issue.

I’m sure that she didn’t connect the door-opening and the mag-buying, but connected they were. For reciprocity – our almost automatic instinct to return even quite small favours – is one of the main forms of social influence identified by the leading social psychologist Robert Cialdini.

His idea – and it’s not one of those bits of pop psychology dreamt up for the daytime TV couch; it’s real academic work based on published papers and careful experimentation – is that we react almost unconsciously, in fairly predictable but sometimes fairly odd ways, to a range of social situations.

Now he and his colleagues Dr Noah Gold-stein and Steve Martin have written a book entitled YES! which reveals what they call “secrets from the science of persuasion”.

I wish I’d read YES! before my recent visit to Legoland. Perhaps then I wouldn’t have found it so puzzling. You see, I found myself staring, bewildered, at my fellow amusement-park visitors. One by one they came to the bandstand and started throwing coins at the feet of the band. Fair enough. The band deserves a tip. But here’s the thing – the band was made of pieces of Lego.

The coin-throwing wouldn’t have bewildered the authors of YES! Alongside reciprocity, social proof is a powerful influencer. We are uncertain how we are supposed to behave, so we look to others for cues. The more those others are like us, the better. See other adults tossing coins? That must be the thing to do.

The power of social proof is extraordinary. If you don’t believe me, read the barely believable evidence in the Yes! extract about dentists.

And here’s another occasion when I wished I’d read YES! – the time my watch was stolen. My insurers gave me a voucher and told me to pick a new watch. I thought I might try something different, something a little more modern, perhaps. That is, until I discovered that my old watch was no longer available (or at least would be hard to obtain). From then on I was obsessed with replacing my watch with exactly the old model. Obsessed.

Again, no surprise to the authors. Scarcity is another big influencer. The words “Closing Down” and “Last Few To Go” are very powerful. Under the Cialdini spell, I once tried selling a tatty old sofa by inviting two couples, “accidentally” scheduling them to arrive at the same time. The result? A furious bidding war for the horrible thing as both feared losing what was obviously a scarce, and therefore valuable, prize. One couple stormed out and the other carried off the sofa in triumph.

The place where I most often see the science of influence at work isn’t Legoland or the watch shop, however. It’s politics.

Why, for instance, are politicians so scared of making “U-turns”? And why do we attack them when they do so? It’s because we value consistency so much. Indeed, once we make a commitment, even a small one, we are desperate to avoid breaking it. Cialdini and his fellow authors show that if we can be persuaded to put a small sign in the window calling for safe driving, we are amazingly susceptible to being persuaded to erect a big hoarding with the same message. We want to maintain our consistent commitment to the road-safety message.

A couple of years back the book Freakonomics was a bestseller, changing people’s idea of economists and their value. YES! is the Freakonomics of social psychology. It’s a handbook to the world. So let me employ a phrase that the authors, with their understanding of scarcity, recognise as a great persuader. Don’t miss out.

Towels in hotels

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 the research scientist Stanley Milgram and colleagues, an assistant of the researchers stopped on a busy New York City pavement and gazed skyward for 60 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.

What if you tried to use these findings to help the environment?

Most hotel guests who encounter those little hotel-towel reuse signs do recycle their towels at some time during their stay. Yet the signs themselves say nothing of this. Instead they deliver a message about the amount of water it would save. What if we simply informed guests of how others behave? Would it influence 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 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 basic environmental-protection message adopted throughout much of the hotel industry. It asked guests to help to save the environment and show their respect for nature by participating in the programme. A second sign utilised the social-proof information with the honest message that most guests at the hotel recycled their towels at least once during their stay. These signs were randomly assigned to rooms in the hotel.

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 had never seen employed by any hotel, were 26 per cent more likely to recycle their towels than those who saw the basic environmental-protection message.

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 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 those who had previously stayed in their particular room, as opposed to the hotel in general? We decided to conduct another study in which some hotel guests saw a request to reuse their towels that communicated the social proof of guests who had stayed in the same room in which they were staying. Their signs said that most previous occupants of the room had reused towels at some point during their stay.

When we analysed the data, we saw that guests who learnt that most others who had stayed in their room had reused towels were even more likely to do so themselves than guests who learnt the norms for the hotel in general. Compared with the standard environmental appeal, there was a 33 per cent increase.

Crafty customer

There is one particular type of person for whom a little favour goes a long way – customer service agents.

If you’ve ever had an incorrect charge on your credit card, tried to make a last-minute change to a plane ticket or wanted to return something, you have probably encountered a less-than-helpful customer service agent.

To reduce the likelihood that you will have such an encounter, try the following: if you find, towards the beginning of your interaction, that the customer service agent is being particularly friendly, polite or responsive – perhaps before you get to your toughest request – then tell the agent that you’re so happy with the service so far that you’re going to write a positive letter or e-mail about your interaction to his or her supervisor as soon as you get off the telephone.

After getting the agent’s name as well as the supervisor’s contact information, you can then get to the more complex issues at hand.

Although there are several psychological reasons why this might be an effective strategy, the norm of reciprocity is a powerful factor here: you have offered to do a favour for that person, so now that person will feel obligated to return the favour. And, for the low cost of writing a quick e-mail to the supervisor afterwards, you can avoid getting into a strategic chess match (and perhaps a screaming match) with the agent that ultimately may lead to disappointment and frustration.

So long as you keep your promise, the strategy should be both ethical and effective.

Tip tactic

Waiters can teach us a great deal about how to be more persuasive.

Many food-servers have found that they receive larger tips when they repeat their customers’ orders back to them exactly as the customer said. Many of us have had the experience of a waiter or waitress taking our order, then passively saying “OK” or, worse still, not even acknowledging the order. Perhaps it’s not surprising that we prefer the service of someone who doesn’t leave us wondering whether the cheeseburger that we ordered will arrive at our table transformed into a chicken sandwich.

A piece of research by Rick van Baaren tested the idea that food-servers who match their customers’ verbalisations after receiving the order will increase their tip size. No paraphrasing, no nodding, no “OKs” – just repeating back, word for word, the customer’s order. In one study, simply by matching their customers’ verbalisations after receiving the order, the food-servers at a restaurant increased their tip size by nearly 70 per cent.

© Robert B. Cialdini, Steve Martin and Noah Goldstein 2007

Extracted from YES! Fifty Secrets from the Science of Persuasion, to be published by Profile Books on November 12, 2007, at £8.99, available from Times BooksFirst at £8.54, free p&p. 0870 1608080

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