This study aims to grasp characteristics on cognition against spatial structure of volumes with random layout by the sketch map analysis of the treatment center for mentally disturbed children in Date, Hokkaido. This building designed by Sou Fujimoto Architects is awarded some architectural prizes. We made two hypotheses from sketch maps of visiting experiment; (1) cognition on spatial structure as a whole could be related to acquiring perception of opening toward outside between volumes, (2) in case developing cognition on the repetition of volumes is not enough, the property of rooms as "Figure" will weaken. As a result of the verification analysis by computer graphic simulations, it has become clear that both of rooms and spaces between rooms in cognition would be reversed as "Figure" and "Ground" each other on spatial structure of volumes with random layout.
