70. Tic-Tac-Toe Prediction
class: tweener | impressiveness: 5/5 | factors: impossible prediction | requires: stuff to write with | watch full episode
The Effect: Just for grins, you play a casual game of tic-tac-toe with a friend. All of the moves are totally fair, and they truly have a free choice of where to play every single move of the game.
Yet once you end in a tie game (as almost every game of tic-tac-toe does), you flip over your prediction of how the match would end up… and the prediction matches the game perfectly.
How it’s Done: First time I had this one performed on me, I was utterly and completely fooled. This is an absolutely brilliant effect from the genius Martin Gardner that you can do anytime, anywhere.
To set up the trick, quietly write down this exact endgame of tic-tac-toe (pictured below), and place it face down nearby. As long as you’re subtle, you can probably do this right in front of your target. Don’t make a big deal about labeling it as your “prediction” and don’t announce that you’re about to do a trick.
To get maximum impact on this, it should feel like a totally organic experience.
To remember this specific endgame pattern, in my mind I always think of the name of this effect as “Oxo, Oxx, Xox,” as if I was reading the three lines as words. Remembering this name phonetically makes memorizing the pattern a cinch.
Start playing a game of tic-tac-toe by drawing the board and placing an x in the middle. As you play, simply follow two rules:
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If they place an O in a corner box, place your X in the box clockwise from it.
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If they place an O in a side box, place your X in the box counter-clockwise from it.
No matter how they play, as long as you follow these rules, you will end up with a draw that will exactly match your prediction. Seriously… try it for yourself a few times.
Two important notes on this effect:
First, the player actually needs to play to win for this to work. Obviously, if he let you get three X’s in a row, it won’t match the prediction. To fix this, I’ll introduce the game by drawing the board and placing my X, then mention “Hey— let’s play tic-tac-toe. If you win I’ll buy you a drink.” Now he’s got motivation both to play and try to win, and has no idea he’s actually participating in the setup to a prediction effect.
Second, although the game will always match the prediction, it may not match the same orientation. Before you turn over your prediction, note whether your game exactly matches your “Oxo, Oxx, Xox” orientation. If it doesn’t, figure out which way you’ll need to turn your prediction to have it match when you flip it over.