Evidence for an eye-movement contribution to normal foveal crowding

Bedell, Harold E. and Siderov, John and Formankiewicz, Monika A. and Waugh, Sarah J. and Aydin, Senay (2015) Evidence for an eye-movement contribution to normal foveal crowding. Optometry and Vision Science, 92 (2). pp. 237-245. ISSN 1040-5488

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Official URL: http://dx.doi.org/10.1097/OPX.0000000000000480

Abstract

Purpose. Along with contour interaction, inaccurate and imprecise eye movements and attention have been suggested to contribute to poorer acuity for “crowded” vs. uncrowded targets. To investigate the role of eye movements in foveal crowding, we compared percent correct letter identification for short and long lines of near-threshold letters with different separations. Methods. Five normal observers read short (4 – 6 letters) and long (10 – 12 letters) lines of nearthreshold, Sloan letters with edge-to-edge letter separations of 0.5, 1 and 2 letter spaces. Percent correct letter identification for the 2 – 4 interior letters in short strings and the 8–10 interior letters in long strings was compared to a no-crowding condition. Results. Letter identification was significantly worse than the no-crowding condition for long letter strings with a separation of 1 letter space, and for both long and short letter strings with a separation of 0.5 letter spaces. Observers more often reported the incorrect number of letters in long than short letter strings, even for a separation of 2 letter spaces. Similar results were obtained during straight-ahead gaze and while viewing in 30 – 40 deg left gaze, where 2 of the 5 observers exhibited an increase in horizonal fixational instability. Conclusions. We argue that lower percent correct letter identification and more frequent errors in reporting the number of letters in long compared to short letter strings reflect an eyemovement contribution to foveal crowding.

Item Type: Journal Article
Keywords: crowding, contour interaction, visual acuity
Faculty: Faculty of Science & Technology
Depositing User: Mr I Walker
Date Deposited: 10 Mar 2015 12:13
Last Modified: 30 Jun 2017 09:44
URI: http://arro.anglia.ac.uk/id/eprint/346462

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