Every kind of human activity in space is made at least different on often more difficult by the peculiarity of the environment, characterized by the almost complete lack of gravity. It is difficult to realize, when staying with our own feet firmly on ground, how life could be altered by the absence of the ever present force of gravity!Among all the psychological faculties directly affected by microgravity, easy and quick orientation, and object identification (as they depend on the visual environment) are analyzed.This work follows on from previously published work (cf. ICES '91) by the authors, highlighting the importance of sensible groundrules in color choice for a space environment, to optimize the above-mentioned capabilities, to which crew performance reliability and safety are directly linked.The presented work (a natural consequence of the above) is a new application of the previously established groundrules to the design of labels and visual cues for the Columbus Attached Pressurized Module (APM).Several aspects of this system have been analyzed, especially from the human factors point of view. It is well known, in fact, that the meaning of visual signals changes depending on the users' cultural background (e.g. stereotypes).Moreover, these cues increase in relevance along with mission duration (e.g. interplanetary missions).Integrating the results of this analysis with the baseline achieved during the previous study (e.g. functional and topological scan of the interior volume), different methods for supporting crew orientation have been proposed for test in the Columbus APM habitability mock-up, where color selection has already been implemented.The approach to tests concerning this subject is, moreover, an important result in a field up to now neglected, especially concerning long duration missions. Therefore, the last section of the work lists some possible assessment methods, considered valid also for further developments.