Eye Movement Responses to a Horizontally Moving Visual Stimulus

EYE MOVEMENT responses to even the simplest visual stimulus moving in only one dimension in an otherwise structureless visual field are the result of activities at several levels. One may distinguish factors operating at three somewhat arbitrarily delineated levels: (a) factors involving the mechanical aspects of the orbit and the other levels intervening between the initiation of the nerve impulses designed to move the eye and the actual eye movement; (b) factors involving the operation of what are often called the psycho-optical reflexes, i. e., the mechanisms which make the eyes move so as to place and retain the image of a light stimulus constantly and accurately on the fovea; (c) factors operating at higher levels of complexity. The first group of factors formed the subject of a recent study,1in which the conclusion was drawn that in an eye movement record of even reasonably high precision they introduce