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The Effect of Aging on Crowded Letter Recognition in the Peripheral Visual Field

Astle, Andrew T.; Blighe, Alan J.; Webb, Ben S.; McGraw, Paul V.

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Andrew T. Astle

Alan J. Blighe

Ben S. Webb

Professor of Visual Neuroscience


Purpose.: Crowding describes the increased difficulty in identifying a target object when it is surrounded by nearby objects (flankers). A recent study investigated the effect of age on visual crowding and found equivocal results: Although crowded visual acuity was worse in older participants, crowding expressed as a ratio did not change with age. However, the spatial extent of crowding is a better index of crowding effects and remains unknown. In the present study, we used established psychophysical methods to characterize the effect of age on visual crowding (magnitude and extent) in a letter recognition task.

Methods.: Letter recognition thresholds were determined for three different flanker separations in 54 adults (aged 18–76 years) with normal vision. Additionally, the spatial extent of crowding was established by measuring spacing thresholds: the flanker-to-target separation required to produce a given reduction in performance. Uncrowded visual acuity, crowded visual acuity, and spacing thresholds were expressed as a function of age, avoiding arbitrary categorization of young and old participants.

Results.: Our results showed that uncrowded and crowded visual acuities do not change significantly as a function of age. Furthermore, spacing thresholds did not change with age and approximated Bouma's law (half eccentricity).

Conclusions.: These data show that crowding in adults is unaffected by senescence and provide additional evidence for distinct neural mechanisms mediating surround suppression and visual crowding, since the former shows a significant age effect. Finally, our data suggest that the well-documented age-related decline in peripheral reading ability is not due to age-related changes in visual crowding.

Journal Article Type Article
Acceptance Date Jun 10, 2014
Publication Date Aug 14, 2014
Deposit Date Oct 24, 2016
Publicly Available Date Oct 24, 2016
Journal Investigative Ophthalmology & Visual Science
Print ISSN 0146-0404
Electronic ISSN 1552-5783
Publisher Association for Research in Vision and Ophthalmology
Peer Reviewed Peer Reviewed
Volume 55
Issue 8
Pages 5039-5045
Keywords Crowding, Aging, Visual acuity, Critical spacing, Reading
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