Zener cards

Zener cards are a tool used in experiments to test psychic abilities like clairvoyance. They consist of 25 cards, each with one of five symbols: circle, plus sign, wavy lines, square, or star. A sender looks at a card and tries to mentally transmit the symbol to a receiver, who guesses the symbol. These tests aim to measure if people can reliably perceive information without using their senses. While interesting, scientific studies have generally found no conclusive evidence supporting extrasensory perception using Zener cards.