August 2023
Volume 23, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2023
Does pre-microsaccadic remapping alter parafoveal crowding zones?
Author Affiliations
  • Krish Prahalad
    University of Houston College of Optometry, Houston, TX, United States
  • Daniel Coates
    University of Houston College of Optometry, Houston, TX, United States
Journal of Vision August 2023, Vol.23, 4727. doi:
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      Krish Prahalad, Daniel Coates; Does pre-microsaccadic remapping alter parafoveal crowding zones?. Journal of Vision 2023;23(9):4727.

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      © ARVO (1962-2015); The Authors (2016-present)

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Large intentional saccades to a peripheral target that is crowded (surrounded by flankers) have been shown to reduce the harmful effects of crowding. While we have recently found that microsaccadic preparation affects performance in a crowded recognition task, its effect on the shape of the crowding zone (e.g. stronger crowding when flankers are positioned radially; radial-tangential anisotropy) remains unclear. Here we had 5 subjects report the orientation of T’s (~20 arc min to the lower left from fixation) that were flanked by two +’s placed 1.25x (~ 6.5 arc min) away from the target that were positioned either radially or tangentially. Eye movements were monitored using a tracking scanning laser ophthalmoscope (TSLO) with a tracking fidelity of <0.5 arc minute to image the retina of the better eye of each observer. The imaging raster was optically overlaid with an LCD display (3840x2160, ~5 pixels per arcminute) used to present stimuli. The target duration was determined individually for each subject (33-66 ms) to provide 75% performance for the unflanked stimuli. Subjects would either saccade (80% trials) or maintain fixation (20%) following cue offset, with stimulus presentation times adjusted based on median saccadic latency. In Experiment 1, subjects were required to saccade to the same location as the target, while in Experiment 2 subjects saccaded to a different location ~20 arc min to the upper left of the target. A pre-saccadic attentional benefit was observed across all conditions for stimuli presented 200 to 100 ms before microsaccade onset. An additional microsaccadic enhancement was observed (stimuli presented <50ms before microsaccade onset) only with tangential flankers, seen exclusively when saccading to the target location (Experiment 1). This suggests a pre-microsaccadic change in the crowding zone, in addition to a general enhancement.


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