Impaired Driving Performance as Evidence of a Magnocellular Deficit in Dyslexia and Visual Stress

Abstract

High comorbidity and an overlap in symptomology have been demonstrated between dyslexia and visual stress. Several researchers have hypothesized an underlying or causal influence that may account for this relationship. The magnocellular theory of dyslexia proposes that a deficit in visuo-temporal processing can explain symptomology for both disorders. If the magnocellular theory holds true, individuals who experience symptomology for these disorders should show impairment on a visuo-temporal task, such as driving. Eighteen male participants formed the sample for this study. Self-report measures assessed dyslexia and visual stress symptomology as well as participant IQ. Participants completed a drive simulation in which errors in response to road signs were measured. Bivariate correlations revealed significant associations between scores on measures of dyslexia and visual stress. Results also demonstrated that self-reported symptomology predicts magnocellular impairment as measured by performance on a driving task. Results from this study suggest that a magnocellular deficit offers a likely explanation for individuals who report high symptomology across both conditions. While conclusions about the impact of these disorders on driving performance should not be derived from this research alone, this study provides a platform for the development of future research, utilizing a clinical population and on-road driving assessment techniques.

Difficulties of Drivers With Dyslexia When Reading Traffic Signs: Analysis of Reading, Eye Gazes, and Driving Performance

“…Fisher, Chekaluk, and Irwin (2015) found that the scores in a self-report measure of dyslexia for adults (the Adult Checklist; Smythe & Everatt, 2001) were positively associated with the number of errors in response to road signs in a driving simulator, and Taylor, Chekaluk, and Irwin (2016) reported that the score in the same checklist was negatively associated with the score on a test assessing road sign comprehension as well as with the scores on some tests measuring situation awareness for road sign information. The authors of these works posited that individuals with dyslexia have trouble with traffic sign processing because they suffer from a general reduced ability to temporally order sensory information, in agreement with the temporal hypothesis of dyslexia (Gori, Cecchini, Bigoni, Molteni, & Facoetti, 2014).…”