Accession Number : AD0733613

Title :   Rapid Changes and Hysteresis in Spatial Integration for Human Rod Vision,

Corporate Author : TORONTO UNIV (ONTARIO) DEPT OF PHYSIOLOGY

Personal Author(s) : Hallett,P. E.

Report Date : 17 AUG 1970

Pagination or Media Count : 15

Abstract : Two previous papers (Hallett, 1969a, b) were concerned with the visual threshold appropriate to a peripheral retinal point and in particular with the rapid changes in point threshold produced by illuminating the dark-adapted eye with large brief duration backgrounds. This paper extends this approach to testing signals of larger subtense. Spatial integration for the rods can rapidly diminish and recover within a few hundred milliseconds. A brief duration background which raises the threshold at a retinal point as much as some steady background is more effective than the steady background in reducing the extent of spatial integration. Hysteresis can be substantial; the extent of spatial integration varies, even for a given point threshold, according to whether the threshold is rising or falling, or temporarily or permanently steady. (Author)

Descriptors :   (*SPACE PERCEPTION, *VISUAL ACUITY), (*RETINA, SPACE PERCEPTION), VISION, HYSTERESIS, THRESHOLDS(PHYSIOLOGY), VISUAL PERCEPTION, ADAPTATION(PHYSIOLOGY), ILLUMINATION

Subject Categories : Psychology
      Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE