Processing speed in perceptual visual crowding

Abstract

In this study, a perceptual visual crowding paradigm was designed to quantitatively assess the detection speed of (un)crowded meaningful visual targets using eyemovement responses. This paradigm was tested in individuals with dyslexia and age-matched controls. Trials were shown on a monitor with an integrated eye tracker to 25 control and 11 dyslexic subjects without any known ocular problems. Each trial started with fixation of a central target. Next, four peripheral targets were shown (left, right, top, bottom), one being a duplicate of the central target. The duplicate was either surrounded by flankers (crowding trials) or shown in isolation (reference trials). The timing of the primary saccades were obtained as a measure for detection speed. The performance of the reference trials was significantly higher compared to the crowding trials (p , 0.05) and a 54% increase in saccadic reaction time (SRT) was found for the crowding trials. The linear mixed model revealed a significant effect of critical spacing and chart type. For the reference trials, no significant differences in SRT were found between dyslexic and control subjects. However, for the crowding trials, a significant increase of ;13% in SRT was found in the dyslexic subjects. A first application of this paradigm showed that dyslexic subjects perform equally well in identifying visual targets in crowded as well as uncrowded scenes compared to controls. However, they seem to need more time to identify targets in crowded scenes, which might be related to the reading difficulties that they experience in general.

Rapid assessment of peripheral visual crowding

“…Our study extends this observation to 6AFC paradigms, demonstrating the utility of eye movements as a valid measure for crowding assessment irrespective of the number of choices in a forced-choice paradigm. This result, coupled with the speed advantage of eye movement-based paradigms over manual response paradigms aligns with the notion of harnessing eye-movement behavior for efficient testing as has been suggested previously ( Murray et al, 2009 ; Grillini et al, 2018 ; Pel et al, 2019 ; Soans et al, 2021 ). The reduction in assessment time for eye movement-based methods is relevant for both clinical and research settings, as quicker evaluations can enhance the feasibility of routine testing.…”

“…Human vision is fundamentally constrained by crowding, affecting our performance in various tasks, including object recognition, reading, driving, and visual search ( Whitney and Levi, 2011 ). Moreover, peripheral crowding effects are reported to be more pronounced in people with certain visual or neurological deficits such as dyslexia, schizophrenia, nystagmus, macular degeneration, and glaucoma ( Geiger and Lettvin, 1987 ; Chung and Bedell, 1995 ; Levi, 2008 ; Whitney and Levi, 2011 ; Kraehenmann et al, 2012 ; Gori and Facoetti, 2015 ; Wallace et al, 2017 ; Ogata et al, 2019 ; Pel et al, 2019 ; Tailor et al, 2021 ; Shamsi et al, 2022 ). Elevated crowding affects the daily life of these groups negatively.…”

“…Elevated crowding affects the daily life of these groups negatively. For instance, crowding significantly slows down the reading of individuals with dyslexia ( Martelli et al, 2009 ; Gori and Facoetti, 2015 ; Pel et al, 2019 ). Likewise, glaucoma patients with elevated crowding may experience difficulties in recognizing faces ( Stievenard et al, 2021 ).…”

“…Previous studies have used eye movements to assess functional vision in a faster and more intuitive manner ( Grillini et al, 2018 ; Soans et al, 2021 ). Eye movements also have been used as a “built-in response method” to replace manual responses when measuring crowding ( Huurneman et al, 2014 ; Yildirim et al, 2015 ; Pel et al, 2019 ) thus liberating participants from the need to use an external keypad or mouse to respond to stimuli. However, previous studies either employed conventional psychophysical methods that required a high number of repetitions ( Yildirim et al, 2015 ) or omitted threshold measurements ( Pel et al, 2019 ).…”

Eye tracking in optometry: A systematic review

“…These studies also analyzed metrics related to different aspects of saccades, such as saccadic rhythmicity ( 9 ; 93 ; 115 ), presaccadic motion ( 66 ), patterns of saccades ( 13 ), characteristics of small saccades and microsaccades ( 37 ; 87 ), dynamic perisaccades ( 55 ), smooth pursuit ( 45 ; 46 ), and visual perception ( 89 ; 128 ). Some articles highlighted data on disparity and deviations between the eyes and different positions of gaze ( 16 ; Barraza-Bernal, Rifai et al, 2017b; 73 ; 86 ; 97 ; 135 ).…”