Effects of text simplification on eye-gaze behaviors in people with aphasia in comparison with neurotypical adults

Background Aphasia causes substantial reading challenges that clinicians may attempt to accommodate by reducing linguistic complexity. Analyzing eye-gaze behaviors provides a method of examining the effect of reading material difficulty on processing by people with and without aphasia.Aims This study’s purpose was to examine eye-gaze differences between people with aphasia and neurotypical adults (NA)when reading material corresponding with 1st-, 4th-, 8th-, and 12th-grade Flesch-Kincaid levels.Methods & Procedures Sixteen adults with aphasia and 16 NAs read five single-paragraph passages corresponding with each targeted grade level while having eye movements tracked. Generalized mixed-effects models tested for grade-level differences on fixation probability on passage words, number of per-word fixations, number of per-word visits, and average duration of word visits.Outcomes & Results Results revealed significant between-group differences for all variables. Multiple within-group pairwise comparisons showed significant eye-gaze differences for participants in both groups as passage difficulty increased. Using NA and 12th-grade passages as referents, significant grade × group interactions occurred for fixation probability and the number of per-word fixations for 1st- and 4th-grade passages read by participants with aphasia.Conclusions Eye-gaze results provide evidence of the slow and laborious process engaged by people with aphasia when reading. Simplifying texts reduced fixation probability for neurotypical adults, but people with aphasia fixated on most words regardless of grade level. In contrast, simplifying texts reduced the number of fixations per word for people with aphasia, but made no difference for neurotypical adults. Combining current results with previous findings suggests materials exceeding an 8th-grade Flesch-Kincaid level may exacerbate post-aphasia reading difficulty, but taking individual strengths, challenges, motivation, purpose and engagement in reading into account is critical.