'The last channel': vision at the temporal margin of the field. Issue 1927 (27th May 2020)

• Record Type: Journal Article
• Authors: Veto, P.; Thomas, P. B. M.; Alexander, P.; Wemyss, T. A.; Mollon, J. D.
• Is Part Of: Proceedings. Volume 287:Issue 1927(2020)
• Publication Date: 2020-05-27
• Subjects: peripheral vision -- motion -- retina -- perimetry -- ora serrata; Biology -- Periodicals; 570.5
• DOI: 10.1098/rspb.2020.0607
• Languages: English
• ISSNs: 0962-8452

Abstract

Abstract : The human visual field, on the temporal side, extends to at least 90° from the line of sight. Using a two-alternative forced-choice procedure in which observers are asked to report the direction of motion of a Gabor patch, and taking precautions to exclude unconscious eye movements in the direction of the stimulus, we show that the limiting eccentricity of image-forming vision can be established with precision. There are large, but reliable, individual differences in the limiting eccentricity. The limiting eccentricity exhibits a dependence on log contrast; but it is not reduced when the modulation visible to the rods is attenuated, a result compatible with the histological evidence that the outermost part of the retina exhibits a high density of cones. Our working hypothesis is that only one type of neural channel is present in the far periphery of the retina, a channel that responds to temporally modulated stimuli of low spatial frequency and that is directionally selective.