Four brightly colored cards are given to your spectators and set on the table in a row. While your back is turned, they turn one card over. Without fail, after placing the cards behind your back, you're able to "feel the colors" and determine which one they selected. The card may be turned over end-for-end or like the page of a book...it doesn't matter. As a kicker, the trick can be repeated with the cards placed in small pay envelopes, and you can still divine which card is upside down.