Abstract
Previous research found poorer heading performance with peripheral as compared to central retinal stimulation, but this may have resulted from the use of small areas of peripheral stimulation centered on the axis of heading judgment (typically, the horizontal axis). These viewing conditions are unfavorable to the visual periphery because 1) small expansion patterns may not optimally stimulate large peripheral receptive fields, and 2) at equal heading eccentricities, regions of optical flow located along the axis of heading judgment are geometrically less informative for heading than regions located perpendicular to the judged axis. We reexamined the contribution of peripheral vision to heading perception with large displays presenting optical flow in regions oriented perpendicular to the axis of judgment. Observers viewed 30s simulations of linear translation through a star field while being rotated about either a vertical (yaw) or horizontal (pitch) axis by a sum-of-sines disturbance. Observers controlled yaw or pitch to orient their perceived heading direction toward the center of a display spanning 90 × 34 deg., H × V. Eye and head movements were monitored in real-time such that moving display elements were presented within the central 30 deg. of the retina or outside 30 de to the periphery. Heading error relative to the display center was continuously measured. Results for yaw-control, in which all moving elements were displayed within 17 deg. of the horizontal axis of judgment, confirmed previous research: central stimulation produced less error than peripheral. However, for pitch-control, in which moving elements were displayed up to 45 deg. from the vertical axis of judgment, error was retinally invariant. Peripheral heading performance appears to be inversely related to the proximity of optical flow to the axis of judgment. Thus, the advantage of central vision may be limited to cases where peripheral flow is available only near the axis of judgment.
Support: AFOSR Grant Nos. F49620-97-1-0093 and F49620-98-1-0482.