Invariance of visual receptive-field size and visual acuity with viewing distance

Abstract

The size of human visual receptive fields was measured by two methods while the observer accommodated on near and distant targets. In one method, interference patterns that were not affected by the state of accommodation of the eye were formed on the retina and used to measure the modulation-sensitivity function of the visual system without the influence of its optics. The spatial frequency to which the observer was most sensitive, which is related to receptive-field size, was not affected by changes of accommodation or convergence. Visual acuity also remained constant when accommodation was changed. In the second experiment, receptive-field size was estimated by determining the size of a superimposed background that most effectively masked a small test flash. As in the first experiment, viewing distance did not appear to influence receptive-field size. It is concluded that size constancy is not a result of changes in receptive-field dimensions.