Une réflexion intéressante tirée du site jerx sur les effets de type "which hand ?"... En gros, pour les non anglophones, ça dit que si on avait vraiment le pouvoir de détecter la vérité et le mensonge, pourquoi le démontrerions-nous avec un jeu de pièce dans la main, "plot" le moins intéressant du monde ?
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I played around with the "which hand" type of effect and a liar/truth-teller presentation a lot this past month. It is, I think, an effect magicians appreciate much more than non-magicians. In fact, my layman-mind is so disinterested in this trick it turned me off to "body-language" and "lie-detecting" as a premise at all for the past few years.
Think of it this way: The idea here is that you're able to tell when someone is lying based on visual or aural clues. Now imagine you really had that skill. Got it? Okay, now I'm going banish you to live on a mountain cliff where you will subsist only on rainwater and tree moss until you can come up with a less interesting way of demonstrating this skill than determining which hand someone is holding a coin in.
You will die on that cliff.
We are literally demonstrating a skill in the least interesting way possible. And why? Well, because people have come up with some clever and interesting ways to determine where the coin is and/or if someone is lying or telling the truth. Clever in method. Interesting to the performer. The audience is just a cog in the process that we're using to keep ourselves entertained.
First, let's look at a procedural issue with this type of trick.
In a lot of these effects the audience is expected to either consistently lie or consistently tell the truth about certain things. I found that people would often get tripped up with yes or no questions if they were supposed to lie all the time. Their life, up until this point, has been about satisfying people with timely and accurate responses to questions. And that's so ingrained in them that -- even when they know they're supposed to lie about everything -- if someone says, "Is the coin in your right hand?" their first instinct is often just to spit out the truth. So I found this happening a lot:
Me: Is the coin in your right hand?
Them: Yes... [pause] Oh, wait, no! No... it's not.
To combat this I would tell them to slow down and take a few seconds to answer the question, but I didn't really like that. I didn't want to seem to be playing any role in how much time they were taking to respond to me.
I found that the best way to handle the situation is not to ask yes or no questions in the first place. Instead I would say something like this, "I want you to keep your role in mind [liar or truth-teller] and when you're ready I want you to tell me which hand holds the coin in a manner consistent with your role." They would take a beat and say, for example, "The coin is in my left hand." This is the same as me saying, "Is the coin in your right hand?" and them answering "No." But it has the advantage that nobody ever fucks it up, and it gets the spectator to put the sentence in their own words which gives you more to work with when you "analyze" their response for lies.