How can you predict what card of nine cards on the table someone will choose?

A trick I've seen performed in a bar: Let's say there is a square of 3x3 cards or coasters on the table (back on top). You are asked to point on a card of your choice without the ';mentalist'; watching (actually touching the card is not necessary). Now the mentalist appears to know what card you chose and points on the same card.How can you predict what card of nine cards on the table someone will choose?
Ok i think i know this trick as i've done it before. There's person A and person B, or ';mentalist'; and the person who picks the card on yours, but i dunno what you mean. So person A and person B both work together on this. Person A would set up the cards on a 3x3 grid, 9 cards. Person B would go away for a while, i'm guessing the ';mentalist';? But ok, Person A would pick one out of those 9 and show the audience, let's say the card at the top right. Person B would come back. Person A then points at a card (not the one at the top right corner), and let's say he points the card at the bottom left corner BUT he'll point the top right corner ON the card he first picked. So now Person B would know that the correct card is at the top right corner. Person A would go around and continue to point cards and ask if that's the one, and when he reaches the card at the top right corner, person B would say yea that's it!



Basically,

-Person B goes away.

-Person A chooses a card (let's say middle) and shows the audience.

-Person B comes back.

-Person A picks a card other than the correct card (let's say middle left card).

-Person A points in the middle of that card, to show Person B that the correct card's in the MIDDLE.

-Person A goes around picking cards until they reach the middle card.

-Person B verifies it.



Confusing but i hope i helped.How can you predict what card of nine cards on the table someone will choose?
I personally think most people would choose the top right.