In the typical Ganzfeld experiment, a "sender" and a "receiver" are isolated. The receiver is put into the Ganzfeld state, or Ganzfeld effect and the sender is shown a video clip or still picture and asked to mentally send that image to the receiver. The receiver, while in the Ganzfeld, is asked to continuously speak aloud all mental processes, including images, thoughts, and feelings. At the end of the sending period, typically about 20 to 40 minutes in length, the receiver is taken out of the Ganzfeld state and shown four images or videos, one of which is the true target and three of which are non-target decoys. The receiver attempts to select the true target, using perceptions experienced during the Ganzfeld state as clues to what the mentally "sent" image might have been.