Sheer Magic: ‘Pick a card – any card! It’s the Queen of Hearts, right?’  When given a choice, we are of course free to select whichever option we want, yet it often happens that somehow the conjurer knows in advance which one this is going to be! How do they do it? Through trial and error, salesmen, advertisers and politicians over the centuries have discovered ways of making sure we pick the right card – the one they want us to. During the past few decades Psychology has painstakingly uncovered some of the mechanisms that people who are in the business of persuading others have long known and exploited. So how do you give people a choice yet at the same time ‘nudge’ them in the ‘right’ direction? Here are some ways (not that we would ever use them…)

Consistency: Study after study has shown that people feel the need to be consistent, and that they use what they have done (or said) in the past as a heuristic about what to do in a given situation. To see how this can be manipulated, just watch this fantastic demonstration by the great Sir Humphrey Appleby:

This is called the ‘Four Walls Technique’ (Levine 2006 – p. 164). You ask the other person a series of rhetorical questions (usually four) before presenting them with a choice. Typically, by that stage they have no option but to say ‘Yes’ or lose face by appearing inconsistent. So, say a student is not certain about whether they would like to attend this optional summer course your school is offering: ‘Do you think English is important today?’  ‘Would you agree that we need to make the most of our time?’ etc… (Not that you would ever do such a thing…).

Perceptual Contrast: Faced with options A and B, you are more likely to choose B if you are given some information about it, after receiving less information about A. For instance, if you spent 1 min talking about coursebook A and then 5 min about coursebook B, chances are your client will go for B. It seems that because people feel they are more knowledgeable about B, that somehow gives them greater confident in their choice. Now here is the bizarre thing: this works even if A is completely unrelated to B! (Tormala & Petty 2007). So, instead of talking about coursebook A, you could spend that first minute talking about a coffee-maker before plunging into your spiel about the coursebook!! OK – now you know what to do if you want a student to go for course B (Not that you would ever do such a thing…).

Cognitive Dissonance: To get students to choose option B, first get them to reject option A somehow! In a fantastic study, researchers offered students 2 M&Ms (say, red and green – though they alternated the colours to avoid any bias). Say a particular student chose the red one. Immediately afterwards they presented the same student with the green one and a blue one. Which one did s/he choose? That’s right – students overwhelmingly chose the one they hadn’t rejected initially; that is the blue one! Because they had rejected the green one initially, somehow the students had constructed a justification in their mind (e.g. ‘It won’t taste good’) and incredibly, this influenced their choice the second time round! (Paul Bloom – YT: Lecture 16, 29:00) So if you would like a student to take Exam B rather than Exam A, just get them to compare Exam A with a clearly better exam C initially (Not that you would ever do such a thing…).

Getting the girls to pick you: Professor Dan Ariely  has uncovered another amazing technique (Ariely 2008 – pp. 11-15). Given options A and B, people are far more likely to choose B if we also introduce a third one, which is very similar to B but clearly inferior (option ‘minus B’). The idea is that because B is clearly better than –B, this superiority ‘spills over’ to A as well! He tested this with actual and computer-morphed faces (see below). In Condition A, most people thought A was better-looking, but in condition B, they thought B was hotter. So now you know… If you are going to a party and your arch-rival is going to be there, you just need to bring along someone who looks like you, but is clearly uglier. Not that you would ever do such a thing… 🙂

Ariely - The Decoy 2


Ariely, D. “Predictably Irrational” HarperCollins 2008.

Bloom, P. “Introduction to Psychology” Yale Courses, You Tube 2008.

Levine, R. “The Power of Persuasion” Oneworld 2006.

Tormala, Z. I. and Petty, R. E. (2007) “Contextual Contrast and Perceived Knowledge: Exploring the Implications for Persuasion” Journal of Experimental Social Psychology, 43: 17-30.