Transmission of Edge Information in the Human Visual System

Abstract

SACCADIC (jumping) eye movements are the characteristic way of moving the eye from point to point. The eye rarely moves in any other way except during tracking. A crucial fact, established definitively by Riggs's¹ and Ditch-burn's² groups, is that the eye continues to make small saccadic movements of about 2–10 min of arc as it fixates a point. Fig. 1 shows how the horizontal component of these eye movements resembles the discontinuous step-function of an electronic square wave. When a saccade occurs, the retinal image abruptly shifts on the retina by an angle equal to the angle of the movement. This simple fact is used here as the basis for a model of the transmission in the human visual system of information about the edges of objects. This fact alone can logically sustain the model, although other evidence will also be presented.