Perceptual psychology is a form of evaluation used for psychological patients. An example of this is the Rorschach test (the one with the inkblots). Tim Noble and Sue Webster took this a step further with their shadow sculptures. They’ve always played with the idea of how humans perceive abstract images and give them meaning. They took bits of rubbish, scrap metal, and even stuffed animals to create a sculpture which throws human-shaped shadows. Oddly enough, some of their work are self portraits.
Check out their website.