The purpose of this study was to compare the sensitivity of humans to angular accelerati on using the perception of rotation and the perception of the oculogyral illusion as two indicators. Ten men with normal vestibular function were studied in a precision rotation device using a random, forced choice, double staircase method to determine the thresholds. The thresholds for the oculogyral illusion were found to be substantially and significantly lower than thresholds for the perception of rotation. The implications of these findings for an understanding of the oculogyral illusion are discussed. © 1968 Psychonomic Society, Inc.