Abstract
Interaction mechanisms between cognition and binocular motor control in reading saccades remain unclear. In this study we examine objectively saccades and fixations parameters during the Stroop test, involving three different levels of cognitive demand (reading, color denomination and interference). In addition, we experimentally induce accommodation and vergence conflicts during the different tasks. Twenty-one visually normal subjects (age 20.9 ± 1.45) performed the Stroop test in three different randomized conditions: a control normal viewing condition, a 16Δ base-out prism condition, and a −2.50D spherical lenses condition. Prisms and spherical lenses induced Vergence-Accommodation conflict. Eye movements were recorded with the Eyeseecam video-oculography device. The results show (1) longer fixation duration in the interference task than in the denomination task, and shorter fixation duration in the reading task; (2) a higher interference effect in the conflict induced conditions compared to the control condition; (3) a lower tolerance to prism induced conflict, with a higher destabilization of the binocular motor control of saccades and fixations. This suggests an interplay between vergence accommodation conflict and cognitive load: tolerance to the conflict seems to be lower in the more cognitively demanding interference Stroop task. The results consolidate the link between cognition and high quality of single binocular vision.
Highlights
Cognitive executive functions, such as action planning, cognitive flexibility or decision making, represent high level processes responsible for the cognitive control of behavior and are known to be related with academic achievement, especially working memory and inhibitory control that are essential for learning and maintaining attention1–4
We demonstrated that asymptomatic subjects with no accommodative or binocular dysfunctions showed higher inhibition performances evaluated with the Stroop test compared to symptomatic subjects with convergence insufficiency
These results suggest that visual processes responsible for clear and single binocular vision could interfere with cognitive processes and attention deployment
Summary
Cognitive executive functions, such as action planning, cognitive flexibility or decision making, represent high level processes responsible for the cognitive control of behavior and are known to be related with academic achievement, especially working memory and inhibitory control that are essential for learning and maintaining attention. We demonstrated that asymptomatic subjects with no accommodative or binocular dysfunctions showed higher inhibition performances evaluated with the Stroop test compared to symptomatic subjects with convergence insufficiency These results suggest that visual processes responsible for clear and single binocular vision could interfere with cognitive processes and attention deployment. Ludlam and Ludlam used base-in prisms on students and demonstrated poorer performances in reading comprehension in the stress-induced condition compared to control These results suggest that an accommodation/vergence conflict experimentally induced could be responsible on lower performance concerning cognitive processes linked to attention and inhibition. Eye movements such as reading saccades and vergence were not investigated in these studies, and the neuropsychological tests used were different, depending on study design
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