No evidence for impaired Statistical Learning in Developmental Dyslexia: an individual differences approach to cognitive correlates

Individual differences in Statistical Learning (SL) are associated with reading ability, yet previous evidence on whether SL is impaired in Developmental Dyslexia (DD) is inconsistent. Furthermore, DD is associated with impairments in rhythmic ability and working memory. This study examined SL in adults with DD compared to Typical Readers (TR), and explored whether individual differences in rhythmic ability, working memory, and vocabulary related to individual SL ability in a speech segmentation experiment.A total of 143 participants (NDD = 25, NTR = 118) were exposed to an artificial language of trisyllabic nonsense-words while neural entrainment to the words assessed SL via electroencephalography (EEG), followed by behavioral SL outcome measures. Aiming to assess individual differences, we linked the neural measure of SL to a battery of tests measuring musicality, rhythmic abilities, working memory, and vocabulary size. Results indicated successful SL in both groups, with similar neural entrainment to the TP-structure during exposure. Behavioral performance in the DD group on SL seemed below TR, though Bayesian analyses rendered this inconclusive. The DD group further obtained lower scores on tasks measuring rhythmic ability, working memory and vocabulary size, but this seemed primarily driven by the latter two. Comparison of relations between neural SL and these tasks indicated no group differences. Exploratively combining the groups resulted in anecdotal Bayesian evidence that individual differences in SL related to working memory and rhythmic ability measured by sensorimotor synchronization. Our results emphasize the importance of an individual differences approach, moving beyond group comparisons based on diagnoses.