Researchers of Fundação de Amparo à Pesquisa do Estado de São Paulo, Brazil have shown that filters attenuate the excitability of the cerebral cortex and help improve dyslexic children's reading speed.
Reading, one of the most difficult activities for children with dyslexia, can be improved by the use of green filters. A study published in the journal Research in Developmental Disabilities points to this fact.
A child with dyslexia has to fix his or her gaze on the words for a longer time to understand a text. Reading speed is slower as a result. For the children without dyslexia, the eye-tracking device detected a statistically significant difference for children with dyslexia, who read fastest with the green filter, fixing their gaze on groups of words for 500 thousandths of a second, compared with 600 thousandths of a second using the yellow filter or no filter. The fixation period with or without filters was 400 thousandths of a second for children without dyslexia.
The improvement in reading time with the green filter might be due to changes in the visual stimuli available for central nervous system processing, suggests the researchers.
Other studies have suggested that colored filters may reduce cortical hyperexcitability in the brain, which may be greater in dyslexic people, thereby attenuating contrasts in visual stimuli and hence improving reading performance.