Using Saccadic Eye Movement Latencies to Measure Retinal Summation Areas

Abstract

A visual tracking method was used to estimate the size of a possible retinal summation area in humans. Stepping luminous targets were presented to subjects whose eye movements were tracked by an infrared device. The size and intensity of the targets were reciprocally adjusted to give constant luminous power at the eye. At a retinal eccentricity of 5 degrees from the fovea, saccadic latency to relatively intense constant-power targets changed little for targets of up to 0,7-1.25 degree diameter, leading to the conclusion that the actual summation area, if one exists, might be of that same size.