Temporal and spatial factors in the fading of diffuse visual images

Abstract

Fig. 1. Taqet patterns used in the exC DCDGD RESULTS Similar results were obtained from both Ss. The data have therefore been combined and the averaged results shown in Figs. 2 and 3. All persistence times refer to the initial disappearance of contour following the start of each experimental run; loss of contour vision is usually brief and can be restored by S blinking or making gross eye movements (Kirkwood, 1967). Equating opaque areas in this way permits evaluation of the effect of configuration largely unconfounded by variations in opaque area, although the physical contrast of the smaller dark regions is also reduced relative to the large opaque areas due to the scattering of light within the cap. Pattern F, the lattice, and G the short line in the central field were designed to investigate differential fading in the foveal and peripheral regions.The Ss were two young adults in good physical health with no readily detectable visual defects. The left eye was used for all observations, the right being occluded by a patch. The S was instructed to report verbally when a uniform gray field was perceived, except for figure G where the criterion was disappearance of the central line. At the beginning of each trial the eye was closed for 10 sec, S then opened his eye, the stroboscope started and E measured the time between eye opening and the report of contour fading. Seven flicker rates were used: 1.2,5.4, 9.5, 13.5, 22, 38, and 72 cps, run in random order. A total of 16 observations were made with each pattern at each flicker rate, except for pattern A where 24 observations were made under each condition.At the end of the main experiment the critical flicker fusion frequency (cft) was determined by the method of ascending and descending series. In this part of the experiment the eye was covered by a plain translucent eye cap. The mean cff was 39.06 cps, (S.E.M =0.865) on the basis of 16 observations.

Sourcebook of temporal factors affecting information transfer from visual displays.

“…Kirkwood (1968) ncticed that blurry images on a large uniform background tended to disappear after a few .…”