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Elie de Lestrange, Tsz Wing Leung, Roger Li, Chea-su Kee; Spatial attention increases paracentral visual acuity under defocused conditions. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1282.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have demonstrated that attention can enhance spatial vision at the attended location. Our current study was set out to ask whether spatial attention alters paracentral visual acuity under defocused conditions.
Five young observers with normal vision performed a resolution acuity task at 1 m. While maintaining fixation at the center of the screen (32-inch, resolution 3840x2160), observers were instructed to attend to two Landolt C locations (north-west & south-east quadrant; along 135/315° with horizontal) at 8° eccentricity in the visual field. On cued trials, a cue was first presented for 300 ms, pointing at one of two upcoming Landolt C locations. Two Landolt Cs (target & distractor) were then presented for 36 ms. At the end of each trial, a response-cue was presented indicating the location of the target Landolt C. The visual task was to identify the location of a gap (6AFC) in the target Landolt C. An interleaved staircase method was used to measure acuity thresholds. An Eye tracker (Tobbi TX300) was used to monitor eye fixation. Three cue conditions were tested. (1) Valid cue condition: The cue pointed at the upcoming target Landolt C location. (2) Invalid cue condition: The cue pointed at the distractor Landolt C location. (3) Neutral condition: Two cue lines pointed at both target and distractor locations. Acuity performance was measured under both natural and defocused (2D blur) conditions. The blurred stimuli were graphically generated with the point spread function for a 5 mm pupil.
Visual acuity varied substantially for the three cue conditions, and also across retinal locations. Specifically, we found that visual acuity performance in the valid cue condition (4.9±0.7) significantly outperformed both the invalid-cued (11.8±2.7) and neutral conditions (6.9±1.1) by a factor of 2.4 and 1.4, respectively (2way RM-ANOVA: F=5.4, p=0.03). The average gains in visual acuity (VAdefocus/VAclear) were 1.55±0.1, 1.2±0.1, and 1.31±0.2 for the valid cue, invalid cue, and neutral conditions, respectively. There was a significant difference in mean acuity performance between the two visual field quadrants tested (NW: 9.5 arcmin; SE: 7.3 arcmin; paired t-test: t=8.0, p≦0.01).
Here we show that attention can increase visual acuity at the attended paracentral location under defocused conditions. These findings may have important implications for sports vision training.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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