SINCE January 1948 the chief problem for investigation by the staff of the Knapp Laboratory for Physiological Optics1 has been the bases on which space perception and spatial orientation are founded. The work is grounded on Luneburg's "Mathematical Analysis of Binocular Vision,"2 which incorporates new and important concepts regarding the fundamentals of space perception, which yields logical and accurate explanations of work already done and facts already known and which promises new possibilities in the experimental and clinical field of vision, with important predictive powers in the fields of art, architecture, industry and war. THE PROBLEM Our problem is to discover, evaluate and mathematically express the fundamental, basic relationships between visual stimuli and the sensation they arouse, to find and verify the constant factors operating in this relationship and to seek and describe the underlying constant relationships between binocular stimulus and resultant sensation on which all the subsequent