Rapid decay of perceptual memory in dyslexia

The basic mechanisms that underlie developmental dyslexia – a difficulty in acquiring reading expertise – are still debated. We propose that such difficulties should be understood within the broad framework of learning and skill acquisition. Behavioral and neural studies, as well as computational analyses, imply that acquiring expertise has atypical dynamics in dyslexia, largely due to reduced perceptual memory, which is manifested in faster decay of perceptual traces of both speech and non-speech stimuli. This faster behavioral decay is associated with faster decay of neural adaptation to stimulus regularities in perceptual cortices. We propose that these atypical dynamics lead to a slower accumulation of language statistics, manifested in reduced complexity of perceptual categories, slower acquisition of words, and – counterintuitively – larger relative difficulties as exposure to stimuli grows.