Maybe a derail, but suggested by the idea of a card-reading test:
When I was a freshman in college, a guy in the dorm was convinced that ESP was real and kept trying to rope people into tests, with little success. One day I was sitting in the game room, reading, and he wandered around trying to get someone to do a card-guessing test with him. He came to me and I said sure, as long as you sit across from me.
He did, took out a deck of cards, and said we would go through ten cards at a time until we hit fifty. He would concentrate on each card, I'd guess, he'd write down the real card and the guess. He got very excited when I scored above 90%. I scored 100% at getting the colors right.
He wouldn't even believe me when I explained that the daylight coming through the window behind him illuminated his cards and that I could read them by looking at the reflections in his glasses. That was why I didn't score a hundred, by the way. Sometimes he was shaking so much I couldn't get the card value right, though I'd always say, "It's a diamond or a heart, can't get more than that. Definitely a red card, though."
He got very perturbed when I kept saying it was a trick, telling me I was afraid to face the truth. I refused to try again, and for some reason after our end-of-term break the guy didn't come back to school.
I wanted it to be crystal clear.
