Sensitivity to full-field visual movement compatible with head rotation: variations among axes of rotation

Movement detection thresholds for full-field visual motion about various axes were measured in three subjects using a two-alternative forced-choice staircase method. Thresholds for 1-s exposures to rotation about different rotation axes varied significantly over the range 0.139 +/- 0.05 deg/s to 0.463 +/- 0.166 deg/s. The highest thresholds were found in response to rotation about axes closely aligned to the line of sight. Variations among the thresholds for different axes could not be explained by different movement patterns in the fovea or variations in motion sensitivity with eccentricity. The variations can be well simulated by a three-channel model for coding the axis and velocity of full-field visual motion. A three-channel visual coding system would be well suited for extracting information about self-rotation from a complex pattern of retinal image motion containing components due to both rotation and translation. A three-channel visual motion system would also be readily compatible with vestibular information concerning self-rotation arising from the semicircular canals.