Visual, auditory and cross-modal processing of linguistic and nonlinguistic temporal patterns among adult dyslexic readers.

This study examined visual, auditory, and cross-modal temporal pattern processing at the nonlinguistic and sublexical linguistic levels, and the relationships between these abilities and decoding skill. The central question addressed whether dyslexic readers are impaired in their perception of timing, as assessed by sensitivity to rhythm. Participants were college-level adult dyslexic and normal readers. The dyslexic adults evidenced generalized impairment in temporal processing: they were less accurate and slower than normal readers when required to detect the temporal gap that differentiated pairs of patterns. Impairment was greatest when processing visual syllables. Temporal pattern processing correlated to decoding ability only among normal readers. It is suggested that high-functioning dyslexics may cope with temporal processing problems by adopting a predominantly holistic, orthographic strategy when decoding. It is proposed that there may be cumulative effects of processing demands from different sources including modality, stimulus complexity, and linguistic demands, and that combinations of these may interact to impact temporal processing ability. Moreover, there may be fundamentally distinct and dissociable temporal processing abilities, each of which may be differently linked developmental dyslexia.