How do magicians use psychology to deliver or present their tricks?
It's rather impossible to delineate any halfway-complete answer to this here on Quora. The question itself is the main subject of countless books, and it would indeed take a book just to give you a decent overview.
I can give you a few exceedingly generalized points here, though.
- People will look where YOU'RE looking. They will follow your eyes.
- People will look where you're POINTING.
- Allowing your audience to discover something on their own is a lot more powerful than if you tell them the same thing. For instance, if my hands are empty (or even if they're secretly hiding something), it is more effective to let them SEE that my hands are empty without my stating it, just in the course of making my movements. But if I say it, it becomes immediately suspicious...and not very convincing.
- Movement attracts attention.
- A large movement will "cover" a small movement; that is, if I'm performing a sleight that involves a movement of my fingers, if I make a larger motion at the same time (say, with my arms or my entire body), it will become nearly impossible to detect the smaller movement.
- If you lead people "down the garden path," in the sense that you are allowing them to suspect that you are using a particular method in order to carry out a trick, and if you then disprove the method that they have been suspecting all along, it will make it very difficult for them to backtrack and figure out the real solution.
- People will remember what you tell them to remember. If I have a spectator cut a deck of cards (which does not actually disturb the order of the cards) at the beginning of a trick, and I then say, towards the end, "You even shuffled the cards at the beginning," they will recall having shuffled the cards, even though they did NOT shuffle the cards, they cut them (which is a very, very different situation for a magician). This is one reason it's so difficult for non-magicians to figure out tricks; because a good magician will have fed them misinformation about what they actually experienced, and the spectator will recall those false details.
- It is very difficult for people to pay attention to some details if you're bringing their attention to other details:
Modern hypnotists tend to use mind-altering drugs (like naxolone; you will all of sudden smell their soaps or colognes really strongly for a minute when they are around you. It'll stick in your mind no matter what.) to present their tricks, maybe its like that.