Minimal evidence of adaptation deficits in children with dyslexia: An EEG study with controlled expectations

Some recent research has implicated the implicit learning of statistical regularities as a potential factor contributing to reading deficits in individuals with dyslexia. These deficits are characterized by weaker neural adaptation compared to typically developing readers, suggesting impaired general processing in forming short-term representations of stimulus consistency. In addition, inconsistent findings have been observed regarding amplitude differences in mismatch negativity (MMN) between individuals with and without dyslexia. To address these inconsistencies, the present study examines neural adaptation and MMN responses in children with and without dyslexia, with the aim of clarifying their potential relationship. Forty-two children with Chinese dyslexia and 26 children without dyslexia participated in an EEG roving paradigm experiment with continuous pure-tone stimuli. Importantly, the stimuli were carefully arranged to minimize expectations and isolate pure adaptation effects. Initial and subsequent adaptation effects were quantified as changes in amplitude in early ERP components (P1a, P1b, and N250), defined respectively as the difference between the deviants and the 2nd tones, and between the 2nd and final tones. In addition, the MMN and late MMN, computed as the amplitude difference between the deviants and the final tones, were extracted. We found that both groups exhibited similar adaptation effects, as well as comparable MMN and late MMN responses, supported by minimal evidence for group differences in Bayesian analyses across most measures. These findings suggest that dyslexia is not characterized by a neural adaptation deficit per se, but that group differences in adaptation and MMN may depend on experimental context and language background.