Quantitative Studies of Some Dynamic Visual Effects

Abstract

The viewing of rotating or rapidly approaching one-dimensional periodic structures results in the perception of a high-contrast band on a uniform structureless surround. For rotating gratings, the width of the generated band is inversely proportional to the angular speed of rotation and the orientation of the band lags behind the direction perpendicular to the grating lines for both clockwise and anticlockwise rotation of the pattern. The amount of lag is proportional to the angular speed of rotation. The width of the band perceived during the viewing of an approaching or receding grating is inversely proportional to its speed, and the orientation of the generated band is along the direction of the lines in the grating. A model is proposed which explains and predicts the effects observed during the viewing of one-dimensional periodic structures in terms of temporal luminance integration in the visual system. The extent to which temporal luminance integration is responsible for the perception of frame or element movement in multielement stimulus frames is also examined. The results obtained with monocularly or dichoptically presented multielement stimulus frames, as well as other relevant psychophysical and physiological data, suggest that the temporal integration responsible for the observed effects is associated with mechanisms of early-stage visual processing which must be located prior to the lateral geniculate nucleus level.