The effects of sensory deprivation are still poorly understood. In this program, six volunteers undergo a 48-hour study of near-total isolation, conducted inside a former fallout shelter. Led by clinical psychologist Dr. Ian Robbins, the experiment has a twofold focus: observation of the subjects during their seclusion—which is enhanced by arm cuffs, heavily filtered goggles, and static-filled earphones—and before-and-after cognitive tests that examine the brain’s central executive functions. Commentary from former hostage Brian Keenan and former Arizona State Prison inmate Paris Carriger sheds light on the physical and mental ordeal of extreme solitary confinement. Original BBC broadcast title: Total Isolation. (50 minutes)