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

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. Although neural adaptation is believed to contribute to MMN, these two processes have been examined in separate bodies of literature, leaving their relationship in children with and without dyslexia unclear. To address this issue, 42 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. The initial adaptation (i.e., the peak amplitude difference between the deviants and the 2nd tones) and subsequent adaptation (i.e., the peak amplitude difference between the 2nd tones and the final tones) effects, including P1a, P1b, and N250, as well as the amplitudes of MMN and late MMN, were extracted. We found that both groups exhibited similar adaptation effects, MMN, and late MMN, supported by minimal evidence for differences in our Bayesian analyses. The relationship between adaptation and MMN was also comparable between the groups. Potential reasons for discrepancies between this study and previous research, including experimental design and language differences, are discussed.