Abstract

Vertical displacement thresholds (DT) were quantified in 24 observers at the fovea and at each of eight retinal positions out to 80° along the horizontal meridian during binocular viewing. Stimulus length was increased with eccentricity angle in accordance with Virsu and Rovamo’s¹ cortical magnification factor; a 1° long stimulus served as a control at each position. Three movement durations (from 0.25 to 4 s) and three angular rates (from 0.04 to 0.42°/s) were also quantified at each position to determine whether peripheral DT is mediated predominantly by an image displacement or rate-sensitive mechanism. It was found that (1) DT is mediated predominantly by a constant rate-sensitive mechanism at each position when stimulus length is increased in proportion to the cortical magnification factor, (2) mean percent correct displacement judgments decrease significantly into the periphery for both stimulus lengths, however, increasing stimulus yields significantly higher accuracy, and (3) at 10° and 30°, increasing rate and duration significantly improve displacement judgment accuracy but beyond 40° only lengthening the stimulus improves accuracy. The findings are related to the design optimization of aircraft dynamic attitude displays and symbology.

© 1985 Optical Society of America