Space psychology is a branch of psychology that studies the patterns which develop in the close quarters of a starship during long voyages in deep space.
Starfleet takes the subject of space psychology quite seriously. For instance, the determination of the state of mind of a captain is important in court martial proceedings, and is facilitated by consultation with an expert in space psychology. (TOS: "Court Martial")
In 2369, several members of the USS Enterprise-D crew attended a three day conference on the psychological effects of long-term deep space assignments. (TNG: "Timescape")
Although the connection has not been established, this discipline is likely connected with exopsychology.