Their movement is restricted by the experimental instructions, but not by any mechanical restraints. Food, drink, and toilet facilities are provided in the room and are at the discretion of the tester, who can communicate with the participants using an open intercom. Subjects are allowed to leave the room before the 24 hours are complete; however, fewer than 10% actually do because they find the chamber so relaxing.[6] Chamber REST affects psychological functioning (thinking, perception, memory, motivation, and mood) and psychophysiological processes.