An insight into the visual sampling strategy: eye-tracking features in dyslexia

Dyslexia is neurological disorder that negatively impacts a person’s ability to read and comprehend textual content. It has varying estimations of prevalence ranging from 5 to 20% of the population, and an early diagnosis is fundamental for a timely intervention. One of the methods that is available for objective reading assessment and therefore contributes to the monitoring of dyslexic tendencies is eye-tracking. Using this technology, it is possible to obtain a better understanding of a person’s reading patterns, or visual attention patterns in general, and thus aid in the diagnostic process as well as the improvements obtained through therapy. In this paper, an introduction to the dyslexia definitions and diagnostic process is given, followed by a review of patterns obtained from eye-tracking for the purpose of dyslexia assessment. The overview of the different features shows the different approaches and their relation to spatial and temporal gaze characteristics as well as their sensitivity to gaze outliers and the total length of the text that is read. The experimental setups are discussed as well, discussing different types of stimuli and their influence. A discussion of different instrumentation, as well as technical requirements that can impact the quality of the obtained features is also discussed, alongside other aspects that can influence feature quality and therefore conclusions that can be drawn from them. Finally, directions for future work related to eye-tracking and dyslexia are given, considering the work presented in the literature and the development of new technologies.