Abstract: It is a well-known fact that depth perception can produce binocular disparity but how is the disparity processed in the visual system is not yetclarified. The concept of spatial freqtiency originally established in physical opticsis now widely used in physiological and psychophysical studies in visionresearch. In order to investigate whether there is any relationship betweendisparity and spatial frequency spectrum, we used mathematical methods toapproach this problem and treated it in three steps: 1. A stereoscopic pair with disparity was made by computer. 2. Transformation of the stereoscopic pair into their spatial frequencyspectra by FFT on computer. 3. Comparison of the spectra of stereoscopic pairs having differentdisparities or different depth. The results are: 1. There are relative shifts in the position of peaks in spatial frequencyspectra of each of the stereoscopic pairs. 2. The direction of shifts depends on whether the side is close toproximal end or distal end of a three dimensional objt which is portrayed as a tilted line in the stereoscopic pair. If a line or curve monotonicallychanged in the depth dimension is observed then the peaks of the spectra ofstereoscopic pair close to the proximal end are shifted to the higherfrequency and those to the distal one are shifted to the lower frequency. 3. The degree of the relative shifts are proportional to the extent ofdisparity. The greater the disparity the further the peaks will shift. 4. There are some indications suggesting that the absolute depth of the3-D object is in someway related to the height of the peaks but not to therelative shifting.

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