Skip to main content
Key Specialties
Cardiology Diabetology Endocrinology Gastroenterology Geriatrics and Gerontology Gynecology and Obstetrics Hematology Infectious Disease Internal Medicine Nephrology Neurology Oncology Pediatrics Respiratory Medicine Rheumatology Surgery
Congress Coverage
2024 ACC Congress 2023 ESMO Congress 2023 EASD Congress 2023 ERS Congress 2023 ESC Congress
Clinical Collections
Advances in Alzheimer’s

At a glance: The STEP trials

A round-up of the STEP phase 3 clinical trials evaluating semaglutide for weight loss in people with overweight or obesity.
ADVANCED SEARCH
Log in
Top
Graefe's Archive for Clinical and Experimental Ophthalmology
Published in: Graefe's Archive for Clinical and Experimental Ophthalmology 7/2004

01-07-2004 | Clinical Investigation

Perceptual salience of global structures and the crowding effect in amblyopia

Authors: Lijuan Liu, Kunming Wang, Bin Liao, Liang Xu, Shihui Han

Published in: Graefe's Archive for Clinical and Experimental Ophthalmology | Issue 7/2004

Login to get access

Abstract

Background

The crowding effect refers to stronger deficits in linear acuity (e.g., letters in a line) than in single letter acuity in amblyopia. The current work investigated whether the salience of a global structure in which the target for identification is embedded influences the crowding effect in amblyopia.

Methods

Compound shapes were presented to the amblyopic and fellow eyes respectively of 12 anisometropic amblyopes. The compound stimuli were presented on either a blank or a cross background so that the salience of global structures were manipulated. Reaction times (RTs) and response error rates were recorded when subjects identified global or local shapes, respectively.

Results

RTs were shorter to global than local shapes for both the amblyopic and the fellow eyes. The global RT advantage was larger for the amblyopic than the fellow eye. Interestingly, when viewing the stimuli with the amblyopic eye, subjects made more errors to local targets when the compound stimuli were presented against the blank than the cross background.

Conclusion

The results suggest that the salience of global structures of visual stimuli contributes to the crowding effect in amblyopia.
Footnotes
1
Minor degrees of eccentric fixation are usually seen in strabismic amblyopia. Thus the difference in behavioral performances of the amblyopic eye with eccentric fixation and the fellow eye with central fixation may arise from the discrepancy between foveal and nonfoveal vision. To exclude this possibility, the current work recruited only anisometropic amblyopes whose both amblyopic and fellow eyes used central fixation. This may simplify the explanation of our results.
 
Literature
1.
Flom MC, Weymouth FW, Kahneman D (1963) Visual resolution and contour interaction. J Optom Soc Am 53:1026–1032
2.
Flom MC (1991) Contour interaction and the crowding effect. Probl Optom 3:237–257
3.
Han S, Humphreys GW (1999) Interactions between perceptual organization based on Gestalt laws and those based on hierarchical processing. Percept Psychophys 6:1287–1298
4.
Han S, Humphreys GW (2002) Segmentation and selection contribute to local processing in hierarchical analysis. Q J Exp Psychol Sect A 55:5-21CrossRef
5.
Han S, Humphreys GW, Chen L (1999) Parallel and competitive processes in hierarchical analysis: Perceptual grouping and encoding of closure. J. Exp Psychol Hum Percept Perform 25:1411–1432CrossRef
6.
Han S, Humphreys GW, Chen L (1999) Uniform connectedness and classical Gestalt principles of perceptual grouping. Percept Psychophys 61:661–674PubMed
7.
Han S, Song Y, Ding Y, et al (2001) Neural substrates for visual perceptual grouping in humans. Psychophysiology 38:926–935PubMed
8.
Han S, He X, Yund EW, et al (2001) Attentional selection in the processing of hierarchical patterns: an ERP study. Bio Psychol 56:113–130CrossRef
9.
Hess RF, Jacobs RJ (1979) A preliminary report of acuity and contour interaction across the amblyope’s visual field. Vision Res 19:1403–1408CrossRefPubMed
10.
Hess RF, Dakin SC, Kapoor N (2000) The foveal ‘crowding’ effect: physics or physiology? Vision Res 40:365–370CrossRefPubMed
11.
Ivry RB, Robertson LC (1998) Two sides of perception. MIT Press, Cambridge, Mass
12.
Kiorpes L, Kiper DC, O’Keefe LP, et al (1998) Neuronal correlates of amblyopia in the visual cortex of macaque monkeys with experimental strabismus and anisometropia. J Neurosci 18:6411–6424PubMed
13.
14.
Navon D (1977) Forest before trees: the precedence of global features in visual perception. Cogn Psychol 9:353–383
15.
Shulman GL, Sullivan MA, Gish K, et al (1986) The role of spatial frequency channels in the perception of local and global structure. Perception 15:259–279PubMed
Metadata
Title
Perceptual salience of global structures and the crowding effect in amblyopia
Authors
Lijuan Liu
Kunming Wang
Bin Liao
Liang Xu
Shihui Han
Publication date
01-07-2004
Publisher
Springer-Verlag
Published in
Graefe's Archive for Clinical and Experimental Ophthalmology / Issue 7/2004
Print ISSN: 0721-832X
Electronic ISSN: 1435-702X
DOI
https://doi.org/10.1007/s00417-004-0881-3

Other articles of this Issue 7/2004

Graefe's Archive for Clinical and Experimental Ophthalmology 7/2004 Go to the issue

Clinical Investigation

Senescence of human multifocal electroretinogram components: a localized approach

Short Communication

Intraocular inflammation following endotamponade with high-density silicone oil

Short Communication

Histological findings of a surgically excised myopic choroidal neovascular membrane after photodynamic therapy

Laboratory Investigation

Induction of apoptosis by the calcium antagonist mibefradil correlates with depolarization of the membrane potential and decreased integrin expression in human lens epithelial cells

Clinical Investigation

Novel 473-bp deletion in XLRS1 gene in a Japanese family with X-linked juvenile retinoschisis

Short Communication

Almost simultaneous onset of Vogt–Koyanagi–Harada syndrome in co-workers, friends, and neighbors