Zener cards are used for testing extra-sensory perception. There are five different Zener cards – a circle, a cross, wavy lines, a square, and a star – that total 25 cards in a pack; five of each design. Develop your own set of recognizable icons that could be used for psychological testing. What comprises a set of objects? Do these objects have a hierarchy? Are they recognizable to your target audience? Your symbols must be simple, direct and stylistically unified across the set. Final cards must be suitable for ESP testing.