I have studied cues that influence the process by which the imagesfrom the two eyes are combined and ultimately lead to our perceptionof 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). Thisrelationship is called the disparity gradient; Burt and Julesz (1980)showed that for foveal (central) stimuli, humans tend to require adisparity gradient of 1.0 or less in order for fusion of the twoeyes' views to occur. I have found that this relationship changes ina systematic manner as the stimuli are placed further into theperiphery. Specifically, larger separations are required to process afixed amount of disparity as the stimuli are moved into theperiphery. I propose that the significant disparity-eccentricityinteraction may be explained by both the progressive loss ofhigher-spatial-frequency channels with eccentricity and a reductionin the range of disparities processed by a channel as eccentricity isincreased. Further, although data across 19 subjects showed similartrends, individual differences across subjects were noted. Thesedifferences suggest that different individuals may have differentpatterns of physiological change as a function of eccentricity withrespect to both the range of spatial frequency channels representedat each eccentricity, and the range of disparities processed by aspatial frequency channel at a given eccentricity. This work issummarized in the June 1997 issue of the Journal of the OpticalSociety of America.