Pre-show work is a common method used by many magicians and mentalists. Pre-show work broadly refers to work prior to the show that would allow the performer to gain or force information, which the performer can use during the show as part of an effect.
Here’s one example. Before the show, the mentalist mingles around with people who are going to see the show. The mentalist approaches Jane and asks her to think of a two digit number. Then as the mentalist looks away, he asks Jane to write down the number on a piece of paper so that she cannot change her mind. The paper is folded up and safely left in Jane’s pocket. The mentalist turns back and guesses “33.” Jane however says that it is wrong. He says, “Nevermind, we’ll try again later. If I call on you later during the show, think of this two digit number.” Secretly though, the mentalist has obtained her two digit number by using an accomplice who peeked at the information from behind while Jane was writing it down. Now during the show, he can call on Jane to think of a two digit number and reveal it. This method is highly deceptive.
Among those who use pre-show work, there are two groups. The first group openly declare their pre-show work. For example, the mentalist may call up Jane during the show and say, “Earlier, before the show, I asked Jane to think of a two digit number. I couldn’t get her number, but now I am going to try again.” Here, the audience now knows what there were things going on before the show which they did not see.
A second group of mentalists never reveals that there was any pre-show work. For example during the show, the mentalist can say the following to Jane: “Now, I want you to think of a two digit number for me. Can I first confirm that I never asked you to think of a specific number? Yes? You made up this number freely right? And this number, now, exists in your mind right?” Jane will say yes to all of this. To the audience, it seems like Jane just thought of a two digit number that only exists in her head. So pre-show work can be hidden from the audience, adding a layer of deception.
There are other kinds of pre-show methods like stalking someone’s Facebook to gain information, or forcing information (eg. asking someone to flip to a page of a gimmicked book and remember the first word on that page which actually repeats on every page). This allows the performer to reveal a lot of information during the show and would seem impossible. The audience cannot back trace this because they have not seen the full process.
Among mentalists, pre-show raises ethical issues, especially when it comes to hiding the fact that pre-show work was done. Ethical issues aside, some mentalists like it and some don’t.
Moral of the story: Now that you have a basic grasp what pre-show is, you know what may be going on whenever a magician or mentalist talks to you before the show. But be nice and don’t go around exposing him/her of course.
Note: Frederick Mentalism: The Singapore Mentalist does NOT use pre-show work.