Take a classic trick. The magician pulls out a pack of cards. You glimpse the five of spades at the bottom and he invites you to pick a card. After a well-timed pause, he asks: 'Is yours the six of hearts?' Amazed, you nod. Of course, all the cards are the six of hearts - apart from the five of spades on the bottom.
The secret to the trick is twofold. First, it takes advantage of the knowledge we already have about a pack of cards. 'If the magician had used tarot cards, the trick might have had less impact,' says Fitzherbert. But seeing an ordinary-looking pack, we open the file in our brain that says '52 different cards'. In business, it pays to be aware of similar preconceptions, of the mental folders opening and closing during a discussion. Understand someone's expectations and you can fulfil - or exploit - them.
Second, we believe whatever our own brain tells us but question whatever someone else tells us. Glimpsing the five of spades, you conclude the pack can't be fixed or the conjuror wouldn't have let you see it. Similarly in business, it's much more effective to allow a prospect to glimpse files on your desk bearing the names of blue-chip clients, rather than clumsily drop them into the conversation.
A word of caution to would-be prestidigitators. Be careful to keep on the right side of the line dividing fact from fiction. Magicians aren't liars - just economical with the truth.