A point light source flickering on and off during a horizontal saccade projects a horizontal array onto the retina. The apparent visual direction of the tail end of the perceived (phantom) array reflects the amount of perisaccadic shift of spatiotopic coordinates that has been completed by the end of the saccade. Four men, saccading 8º to the right across a flashing light, judged the horizontal visual direction of the left (tail) end of the phantom array relative to the left end of a standard 8º array that had projected an image onto the retina before the saccade began. On average, the left ends appeared to be aligned when the last flash in the phantom array was imaged on the retina 7.4º to the right of the image of the left end of the standard array. This result implies that the shift of spatiotopic coordinates is virtually complete by the end of the saccade. A point light source flickering on and off during a saccade projects a pattern onto the retina. The perceived pattern differs from the retinal pattern, with this difference reflecting the perisaccadic shift of spatiotopic coordinates. Hershberger (1987) characterized the perceptual pattern as a phantom array, fixed in space, with the sequential

Abstract--Data concerning the possible role of a corollary discharge mechanism in the regulation of visual-oculomotor interactions are reviewed. Several modes of action for such a mechanism on the processing of visual information are discussed. Mere suppression of visual input during saccades is considered mostly as a peripheral mechanism. It is proposed that corollary discharge could either produce an active cancellation of the effects of eye movements on vision, or contribute to the evaluation that a given visual change is provoked by a saccade. Cancellation could occur at subcortical levels of visual processing although evaluation could occur at the cortical level.

Ma&act-The peripheral and central apparatus for extraretinal (non-visual) sensing of eye position by proprioception (inflow) is documented. The functional significance of this inflowing signal is shown by its role in (I) providing oculomotor stability in fixation and conjugacy, (2) specification of visual direction, (3) development of some visual functions, and (4) depth and vergence responses. Inilow is seen as a slowly-operating calibrator of eye position, with outflow signals read out from the underlying inflow signal. Good “preparations ” for studying inflow include humans having their extraocular muscles surgically manipulated in some way for treatment, or those with some deficit in the afferent pathways. A complete understanding of the oculomotor system, in normal and pathological conditions, demands the inclusion of inflow.

Abstract-When observers tracked a horizontally moving spot, the path of a second spot moving at an angle to the horizontal was radically misperceived. At a signal observers abruptly switched to tracking the second spot, which was then stabilized foveally. Data concerning resulting eye movements and perceptions support a distinction between the “central ” motor command, which is found to be formulated solely from the erroneous perception, and the motor command that finally reaches the eye. which, under some specifiable circumstances, has been “peripherally ” transformed so that the actual motion of the eye is appropriate to the actual motion of the target. INl-RODUCTION Several studies have shown that the paths of motion of spots of light moving in the dark are often strikingly

model of the mechanism for the perceived location of a single