Slipping into the Part - "Cold reading" is a method that psychics use to extract infomation out of their subjects, which they then feed back to the person in an attempt to represent themselves as having psychic powers. Kari Coleman, writing on James Randi's website in part of his newsletter, tells of her experiences practicing to portray a psychic on Penn and Teller's TV show. It's shocking how easy she found it to slip into the role. Read: My Psychic Adventure, by Kari Coleman
(I should add that it was anything but easy for her, emotionally, to deal with her feelings about it)