Left or right hand?
While the magician instructs a spectator what to do (while facing away)a small object (ex. a coin) is hidden by the spectator on his hand. The magician then guesses whether it is in the right or left hand.
1. After the spectator has hidden the object and is satisfied, ask him to close both his fists.
2. Let him raise the hand with the object at forehead level.
3. Tell him to concentrate on that object. Tell him "help me", "forget everthing you are thinking right now", "shout, but only on your mind, left or right". Just keep talking, this should be done 10-15 seconds.
4. Let him place both his hands forward, still with both fists closed.
5. Face him. Because the hand with the object is raised, blood is deprived on that hand. It will appear paler, with fewer vessels. The paler hand is then the hand you will choose. Try it..
This trick is done better while the spectator is standing.
A 5 second hand raise is enough if you have good eyes.
Do not tire the spectator as he will notice what you are trying to do.
Do not do this for so long that it is very obvious that one hand has lots of vessels on it.