Figure 3.

(A) Fundus projection of differential sensitivities to size III targets under photopic conditions. Gridlines are separated by 6°; each circle represents the fundus-projected location in the visual field; relative quantal catches for white stimulus incident on the photoreceptor layer (see Appendix) are depicted by pie charts at each location (blue corresponds to S-cones; gray to absorption by [M+L]-cones; green-red to absorption by the [M versus L]-cone mechanism); insets demonstrate spectral sensitivity (mean of 3 observers ± SEM) with best-fitting template combinations (see text) and their adjusted R² values. Targets at peripheral locations are detected by S-cones and (M+L)-cones whilst targets at fixation are detected by a combination of S-cones, a nonopponent (M+L)-cone and an opponent (M versus L)-cone mechanism. (B) Fundus projection of differential sensitivities to size V targets under photopic conditions. Gridlines are separated by 6°; each circle represents the fundus-projected location in the visual field; relative quantal catches for white stimulus incident on the photoreceptor layer (see Appendix) are depicted by pie charts at each location (blue corresponds to S-cones; gray to absorption by [M+L]-cones; green-red to absorption by the [M versus L]-cone mechanism); insets demonstrate spectral sensitivity (mean of 3 observers ± SEM) with best-fitting template combinations (see text) and adjusted R² values. Targets at peripheral locations are detected by S-cones and (M+L)-cones while targets at fixation are detected by a combination of S-cones, a nonopponent (M+L)-cone and an opponent (M versus L)-cone mechanism.