There always is a catch, unless you have real psychic powers. The key is whether the catch is apparent to the audience.
The first problem is that as mentalists, we want to learn to be real mind readers. We can’t. It is just an illusion. The key is to view that illusion from the audience’s perspective not the performers perspective.
The second problem is that methods are typically unsatisfactory. They seem too simplistic. Once you know the method, it just seems obvious and you can’t see how the audience is fooled.
The third problem is that we cannot convey belief. We know the method, we know it is a trick and our performance shows it.
Finally, we cannot convey context and meaning. Why would the audience care if we can determine what playing card they picked?
If we could do overcome those problems, a mentalism effect would look like this:
Do you ever think about lying? I don’t mean about whether you should lie, but about how frequently people actually lie. The famous poet Gordon Sumner once said that “Poets, priests and politicians all have lies to thank for their positions."
How many times do we lie without thinking about it. When someone asks you how you are doing, you probably reply “good” unless you are a grammar nerd and say “I am doing well.” But you probably say that regardless of how you actually are doing.
There are some questions we are required to respond with a lie. “Does this make me look fat?” “Wouldn’t it be fun to go to the opera for my birthday?” Or when your boss asks “Do you have any plans for the weekend?” knowing that he wants you to spend the entire weekend working on the important sales presentation due on Monday. There is even the question posed by the great philosopher Meatloaf asking “Will you love me, love me forever?” Those lies are hard to detect because we need them to be true and our answers are all but automatic.
It’s the lies you have to think about that get you in trouble. “Why didn’t you get home until late last night?” “How much longer will it take to get that big project done yet?” “How much did you have to drink?” Or the one that always gets my son, “How many chocolate chip cookies did you eat?” We have to think about whether to lie and evaluate what would be the best lie. When you have to think about it... that is when you usually get caught.
So how good of a liar are you? Most people don’t want to be lied to, but tonight I want to find someone who will lie to me. How about you. What is you name? (Spectator says "Amy"). Amy, do you lie often? ("Not to often"). Do you like lying? ("Not really"). Good, people who like lying are often better at it. Who are you here with tonight? ("My husband"). Do you ever lie to him, (laughing, "Sometimes"). [Aside to audience] At least she is honest about that.
We are going to use your lies to determine the truth. We need to start with an incontrovertible truth - Something that can be verified at the end. I have a shuffled deck of cards [fan through cards with deck face up] and I'll shuffle them one more time [shuffle cards]. Take the deck, cut it anywhere you want. Now take the card that you cut to and put it somewhere where I can't see it. Put the rest of the deck in the box and put the box on the table so I can't touch it.
I'm going to ask you two questions about the color of the cards. I want you to answer no to both questions - even if the answer is yes. That is, I want you to lie to me in one of your answers. Is the card you picked black? ("No"). Is the card you picked red? ("No"). I think you were lying the second time because you paused to think about your answer - but don't tell me if I'm right. We can see if my intuition is correct at the very end.
I'm going to ask you about the suit of the cards. I want you to answer both questions no - even if the answer is yes. One of your answers will be a lie. Now make sure you do your best to lie with conviction. Is the card you picked a diamond? ("No."). Is the card you picked a heart? ("No."). That was harder to tell, but I think you were trying too hard to when you had to lie.
Two more questions. I want you to answer no to both questions. I want you to deceive me this time. Is the card a face card... a King, Queen or Jack? ("No."). Is the card a number card, an Ace, 2, 3, 4 all the way up to 10? ("No."). OK, your getting better at lying. I have to ask the questions again. Remember, answer no to both questions. Is the card a face card? ("No."). Is the card a number card or an Ace? ("No."). I think I caught you that time.
Now, since you are getting better at lying, I have to change the rules. It is easy to lie with a yes or no answer, harder to lie with a full sentence. For each of the face cards, I want you to say "My card is not a King" then "My card is not a Queen" and then "My card is not a Jack". OK, say each sentence as if they are true. (Spectator says each sentence). You paused before one of those sentences and unconsciously nodded at me after you finished the same sentence.
So the question is... are you a better liar or am I a better lie detector? Let me draw your card on this big pad of paper. Now take two steps forward so you can't see what I've drawn. I'm going to show the audience what I think your card is. No peeking. You don't want to be both a liar and a cheat. (flip up pad to show Queen of Diamonds). Now I want you to lie one more time. When I tell you to, I want you to say "My card is definitely not..." and then name your card and show the audience the card you are holding. If you name the card that I drew, the audience will give you a big round of applause for being a lousy liar. If it isn't the card I drew, they will probably boo me off the stage for being a fraud. No pressure. Alright, lie for me one more time ("My card is definitely not the Queen of Diamonds"). [Cue Applause].
You have strong enough methods. You just need to use your imagination to turn it into strong performance pieces. My question for you is: what would you consider strong enough?