Change your mind about what? The performers aren't trying to convince you they have psychic powers, they're trying to convince you to buy a ticket to their show.
Anyway, think this through. Derren Brown claims not to use stooges, and has been doing tricks like these on stage (per his wiki page) for 19 tours each averaging 50-100 nights. If he's using stooges, he's going through an awful lot of them, isn't he? Including his TV work, there must be thousands of people in the UK that could go on TV and blow the lid on the whole thing. I ask you, which is the more impressive feat of mentalism: keeping all of those people quiet, or guessing that an audience member drew a picture of a cat?
Anyway, think this through. Derren Brown claims not to use stooges, and has been doing tricks like these on stage (per his wiki page) for 19 tours each averaging 50-100 nights. If he's using stooges, he's going through an awful lot of them, isn't he? Including his TV work, there must be thousands of people in the UK that could go on TV and blow the lid on the whole thing. I ask you, which is the more impressive feat of mentalism: keeping all of those people quiet, or guessing that an audience member drew a picture of a cat?