The spatial-contrast-transfer function of the light-adapted retina is recorded at various eccentricities and the point spread function is evaluated. The estimate of receptive field size thus obtained is compared to that based on data recorded with the aid of a modified version of the Hermann—Hering grid. The order of magnitude of the estimate is found to be the same in either case and to increase from 30° to 60° nasal. However, the conspicuity of the Hermann—Hering illusion is found to decrease when the length of the bars exceeds a given value, which is presumably related to the outer diameter of the contrast detectors. This effect is tentatively ascribed to the coming into play of oblong-shaped receptive units.
LUCIA RONCHI and GIOVANNI FIDANZATI, "Changes of Psychophysical Organization across the Light-Adapted Retina," J. Opt. Soc. Am. 62, 912-915 (1972)