ABSTRACT
A plurality of visual stimuli which simultaneously stimulate the eye, conditions quite a different impression than a plurality of auditory stimuli. No matter how many and how varied are the air vibrations which strike our ears, a spatially extended clang never arises. A clang never possesses anything related to a surface character. On the contrary, the eye has an immediate impression of extension which includes both breadth and depth; at least this is so in the normal adult, and our considerations refer to normal adults. First of all, therefore, we shall consider the visual impression of surface.
