Intact behavioral but atypical neural correlates of visual statistical learning in adults with developmental dyslexia

PURPOSE: The aim of this study was to examine the neural and behavioral correlates of visual statistical learning in adults with and without developmental dyslexia (DD), using a predictor-target paradigm. Reaction times (RTs) and event-related potentials (ERPs) were used to assess participants' sensitivity to predictor-target contingencies that varied throughout the task. METHODS: English-speaking neurotypical adults (N = 36) and those with DD (N = 16) were engaged in a visual statistical learning task while RTs and ERPs were measured. In Phase 1, participants' sensitivity to the contingencies was assessed, in which one stimulus was highly predictive of the target (90 % transitional probability) and another was less predictive of the target (10 % transitional probability). In Phase 2, these contingencies switched to equal probability (50/50), to assess participants' ability to adapt to the change in stimulus predictability. RESULTS: In Phase 1, both groups showed behavioral evidence of learning the contingencies but only the neurotypical group showed ERP effects indicative of learning. In Phase 2, both groups showed similar ERPs and RTs, indicating that sensitivity to the contingencies from Phase 1 persisted into Phase 2 across groups despite the contingencies being changed. CONCLUSIONS: Similar to previous work on children with DD (Singh, Walk, & Conway, 2018), adults with DD showed atypical neural responses but intact motor learning of the visual statistical patterns. These findings suggest that adults with DD may rely on different prediction-based learning mechanisms to acquire visual statistical contingencies, consistent with theories positing differences in visual-attention and basal ganglia-based learning in DD.