Individuals with developmental dyslexia have difficulties with accurate and fluent word recognition and spelling. Hemisphere alluding stimulation (HAS) is one of the neuropsychological techniques to stimulate cerebral hemispheres through the visual vessel, by word selection with various sizes and fonts. It increases the perceptual traits of the text and balances the reading speed by stimulating the right hemisphere. The aim was to investigate the efficacy of the implicit stimulation in visual hemisphere-specific according to the Bakker’s Balance Model for the reading and spelling skills in two students with the linguistic developmental dyslexia. In a single-subject design, two female students (mean age = 9.35 years) were selected through convenience sampling from the 3rd grade in the elementary school. They were diagnosed as having the linguistic developmental dyslexia, evaluated by the Wechsler Intelligence Scale for Children (WISC-IV), who answered the Diagnostic Reading Disorder Test (DRDT) and the Writing Disorder Test (WDT). One student was considered a case subject and the other one a control subject. The case received implicit stimulation in visual hemisphere-specific for 16 sessions (twice a week), but the control subject did not. After the intervention and three months later, the subjects answered the DRDT and WDT again. The results of the visual analysis in combination with the non-overlap methods were used to calculate the effect size. The findings showed that the intervention increased the reading fluency (effect size = 90.74%), reading comprehension (effect size = 69.11%), reading speed (effect size = 200%), and spelling mistakes (effect size = 62.5%) of the case subject. The efficacy of the implicit stimulation in cerebral hemisphere was significant (p < 0.01), even three months later. We conclude that the implicit stimulation in visual hemisphere-specific is probably an effective method for improving the functioning of the reading and spelling skills in people with the linguistic developmental dyslexia.
