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Crowding under scotopic conditions

journal contribution
posted on 2023-07-26, 12:31 authored by Matthew P. Simunovic, Richard I. Calver
Under certain circumstances, a subject's ability to discriminate spatial features of a target may be hampered by neighbouring contours. This phenomenon is popularly known as the “crowding effect”, and it has been intensely studied for photopic vision: little attention has been paid to the effect at lower light levels. The underlying basis of the crowding effect has recently provoked some conjecture, with Hess and colleagues claiming that a passive “physical” phenomenon may either wholly [Vis. Res. 40 (2000) 365], or partially [J. Opt. Soc. Am. A––Opt. Image Sci. Vis. 17 (2000) 1516], account for the effect. In order to investigate the crowding effect under scotopic conditions, we conducted scotopic frequency of seeing experiments for Landolt C targets presented both with, and without, flanking bars; the size of the targets was varied so that frequency of seeing curves could be derived for each stimulus condition. Our results suggest that the spatial extent of crowding is significantly less for scotopic vision than for photopic vision at the same eccentricity––furthermore the effect does not seem to scale in proportion to target size. We also compared the resulting empirical curves to those that would be predicted by the hypothesis of Hess and colleagues. Our results do not support the hypothesis that the scotopic crowding effect is caused by a passive physical process.

History

Refereed

  • Yes

Volume

44

Issue number

10

Page range

963-969

Publication title

Vision Research

ISSN

1878-5646

Publisher

Elsevier

Language

  • other

Legacy posted date

2010-04-29

Legacy Faculty/School/Department

ARCHIVED Faculty of Science & Technology (until September 2018)

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