I have studied cues that influence the process by which the images from the two eyes are combined and ultimately lead to our perception of three dimensions. I focused on the relationship between disparity (difference in placement of same component across the two eyes' views) and separation (between components in each eye's view). This relationship is called the disparity gradient; Burt and Julesz (1980) showed that for foveal (central) stimuli, humans tend to require a disparity gradient of 1.0 or less in order for fusion of the two eyes' views to occur. I have found that this relationship changes in a systematic manner as the stimuli are placed further into the periphery. Specifically, larger separations are required to process a fixed amount of disparity as the stimuli are moved into the periphery. I propose that the significant disparity-eccentricity interaction may be explained by both the progressive loss of higher-spatial-frequency channels with eccentricity and a reduction in the range of disparities processed by a channel as eccentricity is increased. Further, although data across 19 subjects showed similar trends, individual differences across subjects were noted. These differences suggest that different individuals may have different patterns of physiological change as a function of eccentricity with respect to both the range of spatial frequency channels represented at each eccentricity, and the range of disparities processed by a spatial frequency channel at a given eccentricity. This work is summarized in the June 1997 issue of the Journal of the Optical Society of America.