Zener cards

From TinWiki.org

Zener cards are cards used to conduct tests for extra sensory perception (ESP). There are 25 Zener cards in a pack, with five cards each of each design. The five designs on the fronts of the cards are a circle, a cross, a star, a square, and vertical wavy lines. A subject will draw a card from the deck and will try to mentally project the image of whichever design is on that card onto the mind of another person.