IntroductionIn his classic paper, Inui et al. shows the concept of spaciousness for rooms with a window). This concept might be quite ahead compared with other studies around psychological effect of windows), but had long been deserted even in its home country until Munakata et al. have developed it). In these cases, spaciousness is the holistic impression of two spaces: the interior around you and the exterior seen through the window. In a relatively large room such as a living room, which has some partition walls or furniture in it, the interior space is often felt separated to two (or more) sub-spaces). These two cases may be similar because both of them have two spaces. However, these two cases are different, as people usually do not go through the window but usually go around partitions. Thus, the feeling of spatial separation of the interior could be more appropriate than spaciousness or continuity) sometimes. This paper explores the concept of cognition of spatial separation in the interior.MethodsThe study of closed space) was referred to when the space for the experiments are designed. Full-scale models are set using the corridor in a university building. Six settings of partition walls between the space where the seating (or starting) position is included and the other side of the partition were used focusing on the differences in arrangement and size: short walls from the both sides, a short wall in the center, a hanging wall from the ceiling, low partitions (1110 mm, 740 mm, and 370 mm in height).Computer graphics, as well as drawings, photographs and scale models are often used in designing or evaluating architectural space, but these presentation techniques should be used carefully. The depth perception could have important effect on the cognition of separation. Consequently, three experiments were planned for the comparative study as follows.Experiment 1: Computer Graphics. Each subject estimates the projected images on the screen) from the specified seating position.Experiment 2: Full-scale Models. Each subject estimates the real space of full-scale models from the specified seating position.Experiment 3: Full-scale Models. Each subject estimates the real space of full-scale models while walking along the instructed route in the space.Magnitude Estimation method was used in all experiments to estimate the cognition of spatial separation. To investigate the relation between the easiness of movement in the space and the feeling of separation, the impression on “easy to go through – hard to go through” was also graded according to seven ranks. As these are the preliminary experiments to investigate whether spatial separation concept has the possibility for the room design, subjects are twenty students of Kyushu Institute of Design (10 female, 10 male). Most of them are studying environmental design.ResultsIn each experiment, the similar tendency is found among subjects. Consequently, spatial separation is presumed to be a common feeling. The result of Experiment 1 shows that the feeling of separation increases with the height of low partitions, as the easiness of movement decreases. The result of Experiment 2 also shows that the feeling of separation increases with the height of low partitions, although the difference in the easiness of movement between 740 mm and 1110 mm is not apparent. The result of Experiment 3 shows the similar tendency to other experiments, except the impression of the easiness of movement for 1110 mm low partition.ConclusionThe spatial separation concept seems to have strong possibility to be used in the room design. From the comparative experiments, validity of still images of computer graphics for the cognition of spatial separation was confirmed. However, the further work should be needed, as the eye point of the still image seemed to have some influence on the cognition of spaceAcknowledgementThe author would like to thank Mr. Ken’ichi Nagao for his contribution to the experiments.