Magicians Choice

This is one of my favorite techniques. I'm sure many of you are aware of it already, but I thought I'd explain it for those who might not. It can be a very simple yet very powerfull tool for creating an effect, but also it can be a risky one to try, it's usually best to employ it in combination with other techniques to keep the audience distracted and to be quite controlling so as to prevent any awkward questions

The idea is simply to give he impression to the audience that they, or a volunteer has a completely free choice to make that you could not possibly predict, while in fact they have absolutely no choice at all. This is probably best explained with an example of a trick incorporating magicians choice.

What you will need:
21 playing cards and an unsuspecting victim

Method:
Lay out the cards face up in 3 columns of 7 cards each (tip: lay the cards in each column overlapping each other so you can easily pick up each column one at a time). Ask your volunteer to mentally select a card, but not to touch it. They can write it down or tell someone else if you like. Ask them to tell you which column the card is in. Pick up each column of cards placing them on top of each other in your hand ensuring that the column selected goes in the middle. With the cards in your hand face down deal out the same arrangement again, again have your volunteer point out which column their card is in and pick it up the same way with the column they chose in the middle. Finally for the third time deal out the arrangement again and have the volunteer point out which column their card is in.

The Secret:
At this point we know two things, thanks to the wonders of mathematics we know that the card they have chosen is the middle card in the column they point out. You could at this point simply look at that card and use any suitable effect you like. But in this case we also know that if we pick the cards up the same way again with that column in the middle that the chosen card will be the 11th card in your hand.

The Magicians Choice
This is where we can really make the trick special, or equally completely blow it

Deal the cards out face down into an arrangement of squares (4 cards) and triangles (3 cards). Count the cards as you deal them so that you are very sure of where the 11th card goes. You can deal squares first then triangles, the other way around, or alternate, it doesn't matter as long as you know where the card is. Let's assume for now the card is in the 3rd square.

It's a good idea to say something to your volunteer at this point along the lines of "I'm going to ask you some questions now and it's very important that you give me the first answer that comes to you mind, as quickly as you can". You don't want them to be thinking too much at this point

Ask them to choose either triangles or squares. If they choose squares say "ok, we'll keep the squares", if they choose triangles simply say "ok, so we'll discard the triangles". The point being they get to pick between squares or triangles without knowing if you're going to keep or discard what they choose, that's the magician's choice. Keeping it moving quickly, ask them to choose a square, again if they choose the third square keep it, if they choose one of the others discard it. If you're left with two squares, again have them choose and you are now left with the 3rd square containing the chosen card.

You can keep this going right down to choosing the actual card, but most people figure this out sooner or later so a: you need to keep this all moving quickly, and b: it's a good idea to throw in a different effect at this point to mix things up a little. A funny thing about people's memory is that if you can move on quickly enough to a new effect they tend to forget any doubts creeping in about what was happening, all they tend to remember is that they had a completely free choice.

Usually at this point what I would do is pick up all 4 cards, hold them out to the volunteer face down and gripping the chosen card much harder than the others ask the volunteer to slap the cards knocking them out of my hand leaving only their chosen card remaining (or better yet hold them all first time and ask them to hit again but harder).