Mentalism is as much about the patter—what you say and how you respond—as it is about the act itself. For beginning mentalists, it’s easy to get tripped up when your subject starts to ask questions like “if you’re reading my mind, why did you have me write the word down in the first place?” To answer that question, magic blog The Jerx says: don’t worry about it so much.
The whole secret to the illusion is usually in the writing, but it’s only one small part of a routine that fools people into thinking you’re reading their mind. In order to sell it, you have make sure your subject doesn’t realize what you’ve done until after you’ve done it. According to The Jerx, the first step to skate by without having anyone notice is to only bring up the mind-reading after you’ve gotten the word they need—this helps to prevent your target from picking up on how the two are connected.
The most important bit is simple: don’t over-explain or justify why you’re doing what you’re doing. The Jerx gives an analogy:
It would be like if you caught me looking in your medicine cabinet and I said, "Hey, do you have any floss?" That interaction would probably slide by. But if I instead said, "Hey, the reason I opened your medicine cabinet is because I wanted to see if you had floss. I have a popcorn kernel in my teeth and it's driving me crazy. That's why I wanted the floss. To get out that bit of popcorn kernel. The one I mentioned before. The one in my teeth. I know people keep their prescriptions in their medicine cabinet, but I wasn't paying attention to them. I was just looking for floss," you'd wonder what the hell I was up to.
Keeping the explanation simple, direct, and focused on the trick is the best way to move past these sorts of questions. If they really want to know, you can give them a good fib or two once you’ve made their head explode.