SENSITIVITY TO FULL-FIELD VISUAL MOVEMENT COMPATIBLE WITH HEAD ROTATION - VARIATIONS AMONG AXES OF ROTATION

Movement detection thresholds for full-field visual motion about vario us axes were measured in three subjects using a two-alternative forced -choice staircase method. Thresholds for 1-s exposures to rotation abo ut 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 fo und 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 i n motion sensitivity with eccentricity. The variations can be well sim ulated by a three-channel model for coding the axis and velocity of fu ll-field visual motion. A three-channel visual coding system would be well suited for extracting information about self-rotation from a comp lex pattern of retinal image motion containing components due to both rotation and translation. A three-channel visual motion system would a lso be readily compatible with vestibular information concerning self- rotation arising from the semicircular canals.