Orthography-phonology integration of Chinese children with developmental dyslexia: the mutual influence of orthography and phonology

Abstract: Previous studies have revealed that individuals with developmental dyslexia (DD) experienced an orthography-phonology integration deficit. Using functional magnetic resonance imaging, researchers have observed hypoactivation in the superior temporal area when individuals with DD performed an orthography-phonology integration task. Additionally, individuals with DD exhibited a delayed and reduced mismatch negative wave in an audiovisual oddball paradigm when using event-related potentials. However, some studies have found no significant differences between normal readers and DD readers when making decisions about a phoneme preceded by a grapheme. These controversial results may be attributed to the varying manifestations of the mutual influence between orthography and phonology during orthography-phonology integration in DD. Nevertheless, there is a lack of comprehensive research on this topic. The present study aims to explore the mutual influences between orthography and phonology during orthography-phonology integration in Chinese children with DD.
Two experiments were designed to separately investigate the mutual influence between orthography and phonology during orthography-phonology integration in individuals with DD. In Experiment 1, we explored the influence of phonology on orthographic processing. 30 children with DD and 29 age-matched (CA) children participated in Experiment 1. Participants were asked to decide whether a grapheme was real or one invented for the purposes of this study. Each grapheme was accompanied by the presentation of a phoneme, which was either congruent or incongruent with the grapheme. This experiment also included a baseline condition in which only a grapheme was presented. In Experiment 2, we examined the influence of orthography on phonological processing. 32 children with DD and 32 CA children participated in Experiment 2. Participants were asked to decide whether a phoneme was real or invented. Each phoneme was presented with either a congruent or incongruent grapheme. This experiment also included a baseline condition in which only a phoneme was presented. 
The results of Experiment 1 revealed a facilitating effect in the congruent condition compared to the grapheme only condition, but no inhibitory effect was observed in the incongruent condition. Furthermore, no significant group difference was found in the influence of phonology on orthography after controlling for the effect of the only grapheme condition. These findings indicate that Chinese children with DD do not exhibit a deficit in the influence of phonology on orthography during orthography-phonology integration. In Experiment 2, a facilitating effect was observed in the congruent condition and an inhibitory effect was observed in the incongruent condition compared to the only phoneme condition. These effects were significantly lower in children with DD than in CA children. These results indicate that Chinese children with DD exhibit a deficit in the influence of orthography on phonology after controlling for the effect of the only phoneme condition. The collective findings from Experiment 1 and Experiment 2 suggest that Chinese children with DD only exhibit a deficit in the influence of orthography on phonology when integrating a phoneme and a grapheme, while the influence of phonology on orthographical processing remains intact.
In conclusion, the present research provides insights into the mechanism of dyslexics’ deficit in orthography-phonology integration. Notably, this study revealed that this deficit primarily manifests in the influence of orthography on phonological processing. These findings suggest that the orthography-phonology integration deficit in Chinese children with DD may be attributed to an impaired effect of graphemes on phonological processing.