ABSTRACT
Along with the eyes, Nature has created a system to move them about efficiently. The eyes of many species have become specialized in that they contain a small central region in the retina, the fovea, where the photoreceptors are tightly packed which consequently yields high acuity perception. Therefore, to be able to analyze an object in the visual scene in fine detail, the center of gaze has to be directed to it. In addition, when either the object or the person is in motion, it is desirable to maintain the center of gaze on the object. These requirements have produced two distinct systems of conjugate eye movements: the saccadic and the smooth pursuit. The function of the saccadic system is to acquire visual objects for central viewing; the function of the smooth pursuit system is to maintain objects on the fovea while either the object or the person is in motion.
