In order to understand the regional distribution of the mechanisms which underlie localization accuracy we (1) chose a task which is known to involve localization accuracy (2) optimized stimulus parameters for ecentric loci and (3) determined how two key spatial factors which affect localization accuracy vary as a function of ecentricity. These involve Gaussian blur and Gaussian jitter. These results suggest that there are three different functions with ecentricity for the mechanisms underlying this task which we relate to the spatial properties of the retina, namely mean cone density, receptoral convergence and regularity.