Nick Kanas, the "father of space psychology," studies the mental effects of space flight and long periods of isolation on astronauts. From Inside Bay Area:
In the 1980s the kind of "long-duration" space missions (Kansas had) written about were beginning to happen. The Russians had the space station Mir in orbit and American astronauts were on board for lengthy visits.Link (via MindHacks), and more on Kanas in this 2002 NASA article.
These were trying situations. "Most anybody can get along with any body for a week or two," Kanas observes. But longer stays in cramped conditions with no real opportunity for escape are different. Kanas used questionnaires completed on board to discern issues of tension, cohesion and "displacement," the tendency to redirect anger at others. For the cosmonauts and astronauts that was often the ground control.
Kanas looked for what crews at Antarctic research stations call the "third-quarter syndrome." Halfway through any stressful stint, it becomes more difficult to keep anger and resentment at bay. "Think about being with the same person for six months and you don't have a way out," Kanas says. "The groups become less cohesive as time goes on."