Abstract

In human photopic vision the number of ganglion cells analyzing one solid degree of visual field decreases toward the retinal periphery. When the decrease is compensated by magnifying the gratings in inverse proportion to ganglion-cell density (M-scaling) contrast sensitivity becomes independent of eccentricity.¹ M-scaling also applies, for example, to color discrimination, tilt aftereffect, pattern-reversal evoked potentials, Panum's area, and oscillatory movement hyperacuity. M-scaling does not, however, compensate for the increase in size and decrease in overlap of ganglion-cell receptive fields with increasing eccentricity. Neither does M-scaling compensate for the effects of ocular optics and eye movements. There are measures, such as Vernier acuity, fusional vergence response, orientation discrimination, and phase discrimination, that do not become independent of eccentricity by M-scaling. On the other hand, the increase in luminous flux collected by ganglion-cell receptive fields can be compensated by reducing retinal illuminance with increasing eccentricity in inverse proportion to Ricco’s area (F-scaling)². Our recent MF-scaling experiments showed that the increase of visual acuity with retinal illuminance became similar throughout the visual field when ganglion-cell sampling density and the luminous flux collected by their receptive fields were taken into account.

© 1985 Optical Society of America