Time perception for visual stimuli is impaired in dyslexia but deficits in visual processing may not be the culprits

It is known that dyslexics underperform controls in time perception tasks using visual stimuli. However, it remains undetermined whether this deficit is secondary to problems in visual, time-unrelated domains, such as luminance contrasts and/or motion processing. To address this gap, we asked adults with dyslexia and matched controls to perform an interval comparison task involving five different types of visual stimuli with different levels of challenge regarding luminance contrasts and motion. Results showed poorer time discrimination in adults with dyslexia, but this group-related disadvantage did not change according to stimulus type. Complementary analyses of oculomotor behavior during the task suggested that the poorer timing performance of dyslexics may relate to attention and/or engagement with the task. Our findings strengthen the evidence in favor of time perception deficits in dyslexia, but they do not support the hypothesis that these are secondary to visual problems.