How powerful is the ‘power of persuasion’?

The past 50 years of social psychology research has told us that we often do things that we don’t expect, and we often do those things without knowing why.

Back in 1962, Stanley Milgram tried to prove that ordinary Americans would not inflict a lethal electrical shock to an innocent stranger just because they were told to do so by an authority figure. He was trying to demonstrate that the Holocaust was peculiar to the German people, but he was to be disappointed. In reality, 67 per cent of the volunteers in Milgram’s study electrocuted somebody they had just met, when failing to answer a simple question, because Milgram told them to do it. Nobody was actually physically harmed in Milgram’s experiments, but some of the volunteers were emotionally disturbed by their actions (1).

Ten years later, a former student of Milgram, Phillip Zimbardo, tried to prove that liberal college students at Stanford would not behave like guards at Attica if placed in charge of a group of prisoners. Just like Milgram, Zimbardo was to be disappointed. Zimbardo divided a random group of students to roleplay either guards or prisoners in an elaborate mock prison constructed in the Stanford psychology basement. The experiment was intended to last for two weeks but was abandoned after six days because of escalating brutality by the guards (2).

These experiments are classics in the history of psychology, and what they tell us is that people often do not behave according to some predisposition or character trait but according to the conditions and environmental cues they encounter. A more mundane example is the position effect in shopping. In 1976, Nisbett and Wilson set up a stall in a busy shopping centre with four identical pairs of socks placed in a row (3). Shoppers were asked to examine the socks and state which they thought was the best quality. Although the socks were identical, there was a four-to-one preference for the socks placed at the right of the table; shoppers preferred the socks they picked up last. When asked why they preferred those socks the shoppers suggested them to be the highest quality, to have the nicest feel or best shade of colour. No one ever mentioned position as an influence, and if position was raised by the experimenter as a possible influence the shoppers denied it, with an occasional worried glance at the experimenter for asking such an obviously insane question.

If behaviour can be changed, sometimes dramatically, by environmental cues and triggers that are only partially or not at all conscious, then there is the possibility for significant manipulation of behaviour via fairly simple manipulations of the environment. This is the basis of Yes! 50 Secrets From the Science of Persuasion.

In this book, Noah J Goldstein, Steve Martin and Robert B Cialdini document a series of little tricks that can be employed to change behaviour for personal or communal advantage. Many of the examples are entertaining, eye-opening or both. For instance, people show a general inclination to follow the crowd, so if you promote desirable behaviour by pointing out that the majority of people are already conforming, you are on to a winner. Less intuitively, however, if you try to dissuade bad behaviour by lamenting how many people are misbehaving you will end up encouraging the bad behaviour. The notice: ‘Many past visitors have removed the petrified wood from the park, changing the natural state of the Petrified Forest’ actually resulted in more people taking wood from the forest than no notice at all. Those who seek to prevent binge drinking, voter apathy, petty crime and the like by lamenting the high number of participants in such activities should take note.

In a particularly entertaining chapter, the authors describe how Coca Cola executives royally messed up the introduction of New Coke. New Coke had been exhaustively market-tested and was preferred by a clear majority of those surveyed. But when New Coke replaced the old Coke on the shelves, Coke sales plummeted and lawsuits were initiated to bring the old Coke back. Why? Although people tend to like things that are novel and unavailable – we like what we can’t have – people are also intensely sensitive to loss and will go to considerable lengths to prevent loss or mitigate the effects of loss. That is why in October 2003 thousands of people stopped their cars and blocked a major motorway to see Concorde’s final take-off, a sight that had been visible every single day for the previous 30 years or so.

Goldstein, Martin and Cialdini provide tips for how to successfully introduce a new product to your range, or how to write a winning CV, and generally how to encourage people to like you and work with you. It’s all good stuff and very well presented, but there are obvious limits to such tricks. No matter how persuasively your CV might read and look, and no matter how well you ingratiate yourself to the search committee, not having a pilot’s license will mean you can’t fly planes for Virgin, BA or anyone else. Tricks of persuasion cannot substitute for actual knowledge and effort. This is not something the authors claim, but it is not something they spell out either.

Furthermore, many of these tricks of persuasion only work so long as the secret remains a secret. Once people realise that their behaviour is being manipulated, the trick works less well. We become suspicious of the over-welcoming shop assistant and question the motives of the waiter who provides the ‘personal touch’. Even without overt realisation, the tricks can start to bump up against each other, becoming unwieldy and difficult to manage. Getting you to do me a favour will tend to make you like me but not if I ask for too large a favour, and I need to be sure to recognise the favour you did me pretty quickly and in an appropriately personable fashion…

The tricks can also get old. Milgram mobilised a deference to authority that was prevalent in the 1960s but is largely absent today. Currently we are struggling to ensure that our undergraduates take their research participation seriously enough to follow coloured lights on a screen. I’m not sure we would be very successful in getting them to shock someone to death. An attempt at replicating the Zimbardo study in 2002 failed to produce anything approaching Attica (4). The volunteers’ main complaint was of boredom (5).

In short, life is too complicated to yield in an important way to a simple box of psychological tricks. Our lives are historical, deep and substantive, and often require real knowledge and talent in order for our goals to be realised.

Still, if you want to manipulate a bigger present out of your loved ones this Christmas, you could try this: First ask for something enormous, a detached house in Kensington for example. When that is rebuked follow with a request for what you really want – that new Jag. Perceptual contrast will ensure that the new Jag now looks a quite reasonable request. State that you are going to buy them something enormous, preferably in writing using a post-it note stuck to their Christmas card. The norm of reciprocity will create feelings of obligation to match your gift, and the personalised note will ensure they remember. Finally, do this to everyone you know so as to create conformity effects. Then, on Christmas morning, take your fleet of new Jags to the hills – you won’t be welcome for Christmas dinner.

Stuart Derbyshire is a senior lecturer at the School of Psychology at the University of Birmingham, England.

Yes! 50 Secrets from the Science of Persuasion by Noah J Goldstein, Steve Martin and Robert Cialdini is published by Profile. (Buy this book from Amazon(UK).)

(1) Milgram, S. ‘Behavioral study of obedience’, Journal of Abnormal and Social Psychology, 1963; 67: 371-8

(2) Extensive details of the Stanford prison experiment can be found here.

(3) Nisbett RE, Wilson TD. ‘Telling more than we can know: verbal reports on mental processes’. Psychological Review 1977; 84: 231-259

(4) Haslam SA, Reicher S. ‘Beyond Stanford: Questioning a role-based explanation of tyranny’. Bulletin of the Society for Personality and Social Psychology, 2003;18:22-25

(5) Speaking to the Psychologist in 2002, Haslam and Reicher commented: ‘after the event, a number of the participants expressed disappointment because the study was far less stressful than they had been led to expect’.