Zener cards, also known as ESP cards, are a set of cards used in parapsychology and extrasensory perception (ESP) research. Developed by psychologist Karl Zener in the 1930s, these cards are designed to test and explore individuals’ psychic abilities and their potential to perceive information beyond the five senses. A typical set of Zener cards consists of five different symbols: a circle, a square, a wave, a cross, and a star. During an experiment, the cards are shuffled and one card is randomly selected, with the person being tested attempting to identify the symbol without any sensory cues. Zener cards have been utilized in various scientific studies investigating telepathy, clairvoyance, and other forms of psychic phenomena.