No radio silence, no bland food and above all, no competitive board games.
Observing these rules is critical to preserving the mental health of 33 Chilean miners trapped inside a northern gold and copper mine as they begin what could be a months-long wait for extraction.
Rescue workers finally made contact with the men on Sunday after two weeks of failed attempts to discern whether any had survived an underground tunnel collapse on Aug. 5. The jubilation that followed was quickly tempered by revelations that it will likely take four months to dig a tunnel wide enough to lift the men out of the mine - an almost unfathomable timeline that raises new concerns about the psychological grind the workers now face.
Their situation is unusual even to the world's foremost experts on survival in extreme environments, who base their studies on astronauts assigned to the International Space Station and polar stations in the Arctic and Antarctic - isolated postings that are preceded by sophisticated training sessions on how to endure them.
"One kind of mixed advantage is that there are so many of them. Most isolated environments have a lot fewer people than that," said psychologist Peter Suedfeld, a professor emeritus at the University of British Columbia, who consults for the Canadian Space Agency, the National Aeronautics and Space Administration and the Canadian Department of National Defence.
"The advantages are that if some particular expertise is needed, there's a better chance somebody can fix things or soothe people if they get upset," he said. "The disadvantage is that there can be cliques and competition and rivalry. Disagreements can bloom into serious controversy … things that seem trivial on the outside can develop into violence and permanent feud and hatred," he said, adding: "It's not as if they volunteered to work at the South Pole for four months. They're not in there because they asked for it."
Because the group is so large, there is a danger that cliques might be formed over the distribution of desirable things, such as food, reading materials or access to cellphones. It's almost certain that a leader will emerge within the group; if the history of expeditions is any indicator, it's also possible that an overthrow attempt will be staged.
"Sometimes it develops into fighting, mutual isolation," Dr. Suedfeld said of the cliques. "You can't afford to do that when you're in an emergency situation."
Working in the miners' favour is the fact that they seem, almost three weeks into their ordeal, to be functioning as one unit. The men used tools they have underground to establish a light source and to power their head lamps - after food and water sources, establishing reliable access to light is critical to staving off psychological deterioration.
"The most important thing, aside from keeping physical needs satisfied, is to help them keep a positive frame of mind," Dr. Suedfeld said. "Darkness is disorienting. It leads to uncertainty. That leads to anxiety and fear."
Constant darkness can also disrupt the body's sleep and wake cycle, which, over a long period of time, can cause the onset of seasonal affective disorder as well as exhaustion, depression and anxiety.
Almost as important as light is the group's ability to maintain contact with people above ground, including family members. Astronauts on postings to the International Space Station (which is manned by just six people) can telephone their families daily; they have consistent connection to the Internet and often receive "surprise" phone calls from celebrities or favourite authors arranged through NASA's psychological support arm.
"In isolation and confinement, even when you're very, very busy, one day blends into the next," said Jack Stuster, a California psychologist with a California-based research company that contracts with NASA and the U.S. military to study human performance in extreme environments. "It's nice to have important events to serve as milestones," he said, adding: "The real thing is that they have nothing to do. That is a problem."
Both psychologists say it's critical that emergency workers provide the trapped miners with something to keep them "meaningfully engaged" while they wait, including music, reading material and journals to write in.
Board games, however, don't qualify.
"That exacerbates the potential hostility," Dr. Suedfeld said. "You don't want to give them anything that raises antagonism."
What the miners should be given, both doctors said, is good food.
"My recommendation would be that when they send food down not as whole meals, but as food that could be assembled into a meal so they [the miners]have the occasion to prepare meals," Dr. Stuster said. "In a situation where there's no meaningful work to perform ... food takes on an added importance."