3 DIMENSIONALITY OF THE RECOGNIZED VISUAL SPACE OF ILLUMINATION PROVED BY HIDDEN ILLUMINATION

We hypothesized that the recognized visual space of illumination (RVSI ) was constructed in our brain when we grasped the state of illuminati on of a space. The importance about the RVSI is that it is three dimen sional and is valid not only at the surfaces of the existing objects i n the space, but also for the entire portion in the space where no obj ects exist. With this property of RVSI we are able to predict the appe arance of an object surface in terms of lightness as well as of color when the object shifts from one place to the other in the space. The t hree dimensionality of the RVSI is proved by giving a hidden illuminat ion within a space and by asking a subject to judge the lightness or c olor of a test patch placed in the area of the hidden illumination. In spite of the additional light on the test patch the subject did not r ecognize that the light was added but simply felt that the surface was made of a higher lightness or colored by transferring the light into an increase of the reflectance factor of the test patch. The results c an be interpreted if we assume that a same RVSI exists throughout the entire space including the area of the hidden illumination.