Sensory auditory interval perception errors in developmental dyslexia

Developmental dyslexia (DD) is a heritable condition associated with reading, visual and auditory deficits. Atypical processes involved in low-level sensory coding have been implicated. We tested the contribution made by auditory magnocellular function using a behavioural task which considered the temporal difference between pairs of identical sinewave tones. Adult undergraduates with an existing diagnosis of DD (n = 78) were compared with controls (n = 111) from the same population on error rates and response times at different interval durations. Error rates and response times increased in both groups with increasing task difficulty. However, on average the DD group made uniformly more errors and slower decisions than controls. Unsupervised learning of error patterns exposed a trait continuum associated with individual differences in response efficiency. Difficulty in using temporal information in DD arising from impaired sensory coding in the auditory thalamus is suggested. The results provide strong support for the idea that auditory processing difficulties in dyslexia, along with visual and sensorimotor deficits, have a common neurodevelopmental cause.