Influence of maintained ocular deviation on the spatial displacement component of the oculogyral illusion

Abstract

We evaluated the effect of maintained gaze deviation on the displacement component of the oculogyral illusion (OGI). Whiteside, Graybiel, and Niven (1965) proposed that the perception of an OGI was dependent upon the central monitoring of a fixation command needed to suppress vestibular nystagmus and maintain a retinally stable target. By employing a procedure developed by Alexander (1922), we varied the fixation signal strength needed to maintain stable target fixation during rotation, and found systematic and predictable differences in the magnitude of the displacement component of the OGI. These results suggest that the visual fixation signal needed to override a covert vestibular nystagmus is used in computing the visual direction of a target, and provide support for the theoretical analysis of the OGI proposed by Whiteside, Graybiel, and Niven. © 1987 Psychonomic Society, Inc.