Individuals with dyslexia use a different visual sampling strategy to read text

Léon Franzen,Zoey Stark,Aaron P Johnson

doi:10.1038/s41598-021-84945-9

Abstract

Individuals with dyslexia present with reading-related deficits including inaccurate and/or less fluent word recognition and poor decoding abilities. Slow reading speed and worse text comprehension can occur as secondary consequences of these deficits. Reports of visual symptoms such as atypical eye movements during reading gave rise to a search for these deficits’ underlying mechanisms. This study sought to replicate established behavioral deficits in reading and cognitive processing speed while investigating their underlying mechanisms in more detail by developing a comprehensive profile of eye movements specific to reading in adult dyslexia. Using a validated standardized reading assessment, our findings confirm a reading speed deficit among adults with dyslexia. We observed different eye movements in readers with dyslexia across numerous eye movement metrics including the duration of a stop (i.e., fixation), the length of jumps (i.e., saccades), and the number of times a reader’s eyes expressed a jump atypical for reading. We conclude that individuals with dyslexia visually sample written information in a laborious and more effortful manner that is fundamentally different from those without dyslexia. Our findings suggest a mix of aberrant cognitive linguistic and oculomotor processes being present in adults with dyslexia.

Highlights

Readers without dyslexia[35,37,38,39,40]
Most of our current knowledge about differences in eye movements in dyslexia is provided by researchers investigating either a limited number of eye movement metrics in relation to specific linguistic aspects most often embodied by a target word (e.g.,51–53), or is limited by the use of a large variety of often controlled but non-standardized linguistic stimuli in several languages with varying orthographic depth ranging from one character up to one or two s entences[54,55,56,57]
To avoid obtaining an eye movement profile biased by font type, we presented half of the texts in OpenDyslexic (Fig. 1b,c)

Summary

Introduction

Readers without dyslexia[35,37,38,39,40]. The difference in reading rates between affected and non-affected adults with dyslexia can equate to the difference observed in early r eaders[39,40,41]. We aim to devise a comprehensive eye movement account of adult dyslexia by investigating how eye movement patterns of individuals with dyslexia differ from those without dyslexia on global (text-based) and local (word-based) reading measures during an ecologically valid silent paragraph reading task in English (Fig. 1a). Linguistic parameters such as the difficulty of a text[58,59], its s yntax[60,61], word length and word f requency[62] can impact eye movements, highlighting the importance of using standardized and validated stimuli. Scanpaths of readers affected by dyslexia are hypothesized to be longer and to differ in their sequence and duration of eye movement events as a result of increases in reading duration

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Conclusion