Size and Luminance Discrimination in the Peripheral Visual Field,
Abstract
The detection of a stimulus in a complex environment is likely to depend on how different the stimulus is from the other elements in the visual field. The discrimination of length differences of two bars and size and luminance difference of two discs were measured as functions of the angle of eccentricity between the fixation point and the stimulus. The experiments were undertaken to provide basic data necessary for the interpretation of later experiments involving the detection of discs embedded in a complex background which in turn elucidates the determinants of camouflage. It was found that (1) discs are discriminated in size by virtue of their difference in diameter rather than their difference in area, (2) the 50% and 90% levels of detection probability of size and luminance contrast between two discs are linear functions of eccentricity at least to 14 deg eccentricity, (3) the visual system is better at discriminating size contrast at all eccentricities tested than it is at discriminating luminance contrast, (4) there is a fundamental difference between the mechanisms which mediate size and luminance discrimination. Models are proposed which could account for this difference.(Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1979
- Accession Number
- ADA081839
Entities
People
- Stephen E. Jenkins
Organizations
- Defence Science and Technology Group