This article was produced in partnership with the Pulitzer Center on Crisis Reporting.

GUANTÁNAMO BAY, Cuba — For years, starting from the time they were held and interrogated by the C.I.A. after the Sept. 11, 2001, attacks, the prisoners spent their days and nights in isolation, each man locked alone in a cell, at times engulfed in darkness and white noise.

During the period they were held in the C.I.A.’s network of secret prisons, they would get solid food if they pleased their American captors, liquids if they did not and a mock medical procedure called “rectal feeding” if they refused their rations.

Later, once they arrived at Guantánamo Bay and were placed in the base’s most clandestine of lockups, called Camp 7, they were kept in isolation most of the day. When they were allowed out of their cells, guards would take them in shackles and chains so short they could only shuffle.

Times have changed. Now the military allows the 14 former C.I.A. prisoners to walk unencumbered from their cells in two separate blocks, known as Alpha and Bravo, to enclosed open-air, recreation pens. There, they can pray and share meals together, in groups of six or eight. Some prisoners on Bravo block have fashioned a Ping-Pong table.