Ulster University Logo

Effect of Light Adaptation on the Orientation Acuity of Human Cone Vision

Zlatkova, Margarita and Vassilev, Angel (1991) Effect of Light Adaptation on the Orientation Acuity of Human Cone Vision. Acta Physiologica et Pharmacologica Bulgarica, 17 (2-3). pp. 47-53. [Journal article]

Full text not available from this repository.


At the detection threshold, a line orientation is identified by the accuracy of 15-20 deg. Deviations from this rule are observed for short lines presented on a dim background. We checked up for one possible source of deviation: the substitution for foveal cone vision by peripheral rod vision. Long wavelength (red) light was used for the test line. In a control experiment such light did not stimulate rods. The test line was 4 min of arc long. It was presented for 20 ms on a white background of 1 or 1000 trolands and was viewed foveally. In a 2-alternative forced-choice experiment the psychometric functions for detection and orientation identification (vertical v. horizontal) were compared. In another experiment, the line was presented randomly in one of 18 orientations in the range 0-180 deg and the subject was asked to determine the orientation. In both experiments orientation perception was impaired at the dim background in comparison with the results at the bright background. This suggests that light-adaptational changes of the mechanisms responsible for orientation perception exist within the photopic vision.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences > School of Biomedical Sciences
Faculty of Life and Health Sciences
Research Institutes and Groups:Biomedical Sciences Research Institute
ID Code:23298
Deposited By: Dr Margarita Vidinova
Deposited On:12 Sep 2012 13:03
Last Modified:23 May 2017 14:32

Repository Staff Only: item control page