Impaired and Spared Auditory Category Learning in Developmental Dyslexia

Categorization has a deep impact on behavior, but whether category learning is served by a single or multiple systems remains debated. Here, we designed two well-equated nonspeech auditory category learning challenges to draw upon putative procedural (information-integration) versus declarative (rule-based) learning systems among adult control participants and individuals with dyslexia, a language disorder related to a selective disruption in the procedural memory system and in which phonological deficits are ubiquitous. We observed impaired information-integration category learning and spared rule-based category learning in the dyslexia group compared to a neurotypical group. Quantitative model-based analyses revealed reduced use of, and slower shifting to, optimal procedural-based strategies in dyslexia with declarative-based strategy use on par with control participants. The dissociation is consistent with multiple category learning systems and points to the possibility that difficulty in phonetic category acquisition in dyslexia may arise from procedural learning inefficiencies across categories defined by complex, multidimensional exemplars.