MODEL RELEASED. Extra-sensory perception test. Conceptual image of a man undergoing a test for extra-sensory perception (ESP) powers. The image on his forehead represents his correct prediction of the symbol on the card in the examiner's hand. These are called Zener cards, and there are five possible symbols to choose from. To be impartial and objective, such tests should avoid possible unconscious communication by body language or voice intonation between the subject and the examiner.