Factor analysis of semantic differential data, with forty-eight cases of collegiate lecture rooms psychologically assessed by students during regular classes, has established that distance evaluation forms diagonal coordinates together with overall evaluation. Multiple regression analysis has then explained psychological distance in five variables: room depth, natural lighting, illumination, window-opening ratio and student density. The ratio of room depth to breadth and main window area on both sides are also explanatory variables, supporting hypotheses of tunnel effect and window-frame rhythms as increasing factor. A multiple-regression equation explaining 69.4% of variance has revealed that 100～180 lx increase of illumination should compensate 1.8m decrease in room depth.
