Filtered Text and Direction Discrimination Training Improved Reading Fluency for Both Dyslexic and Normal Readers

Optometry & Vision Development Abstract Background: Over 67% of children in 4th grade are reading below grade level, which means they are twice as likely to drop out of school. Previous research has found that children who are slow readers have reduced contrast sensitivity for detecting the direction of movement, and that improving their movement contrast sensitivity by training with sinusoidal gratings moving relative to fixed background gratings significantly increases their reading fluency. Since observers having reduced contrast sensitivity show much faster reading speeds when text is sharpened with digital filters, it is likely that children will also read filtered text more quickly than unfiltered text. Methods: Orientation discrimination contrast thresholds were measured for both dyslexic and normal readers in grades kindergarten through third grade and used to construct individualized digital image enhancement filters. Computer-based reading speeds were measured for both unfiltered and filtered grayscale text before and after training on direction discrimination. Following training, reading speeds for both unfiltered and filtered equiluminant colored text were measured as well. Results: Reading rates were twice as fast when utilizing filtered text to compensate for losses in orientation discrimination contrast sensitivity compared to unfiltered text, both before and after direction discrimination training. Both filtered and unfiltered colored text was read at least 30% more slowly than filtered or unfiltered equiluminant grayscale text. The effects of training on direction discrimination were also significant for both dyslexic and normal readers (p < 0.008), doubling reading rates for both dyslexics and normal readers. Following training on direction discrimination, contrast sensitivity functions improved an average of fourfold for normal readers and five-fold for dyslexics, showing rapid perceptual learning in children aged 5 to 8 years. Conclusions: Finding much faster reading speeds for filtered text shows the value of individualized contrast enhancement to improve reading skills. These image enhancement filters are unique and work well to improve the reading performance of children with contrast sensitivity losses. Moreover, training on direction discrimination improved the reading fluency of both dyslexic and normal readers. Furthermore, the fact that colored text was always read much more slowly than equiluminant grayscale text may also suggest that the colored backgrounds produced by the Irlen lenses do not improve reading fluency. Finally, both digital image enhancement and direction discrimination training provide effective, convenient, and relatively inexpensive tools to improve reading.