The present study focuses on examining the hypothesis that auditory temporal perception deficit is a basic cause for reading disabilities among dyslexics. This hypothesis maintains that reading impairment is caused by a fundamental perceptual deficit in processing rapid auditory or visual stimuli. Since the auditory perception involves a number of mechanisms and temporal processing is only one of them, in the current paper, we tested, in addition to auditory temporal processing, also auditory intensity and spectral processing among dyslexic and normal readers. In addition, we examined whether poor performance of dyslexic readers in auditory temporal processing tasks results from a difficulty in working memory, by testing differences in auditory processing, controlling for working memory.Thirty-seven adult dyslexic readers and 40 adult normal readers performed a battery of tests measuring auditory temporal processing (gap detection and dichotic temporal order judgment), auditory intensity processing (absolute threshold and intensity discrimination), auditory spectral processing (spectral temporal order judgment) and working memory (backward digit span). Performance on auditory spectral and temporal processing task was poorer among dyslexic readers, as compared to normal readers, even after controlling for working memory, but no difference was found in intensity processing tasks. These results suggest that dyslexic readers exhibit a specific deficit in auditory temporal processing, which cannot be attributed either to general perceptual deficit in auditory processing, or to working memory.

Dyslexia is a neuro-cognitive disorder with a strong genetic basis, characterized by a difficulty in acquiring reading skills. Several hypotheses have been suggested in an attempt to explain the origin of dyslexia, among which some have suggested that dyslexic readers might have a deficit in auditory temporal processing, while others hypothesized that dyslexia origins from a deficit in working memory. The current study was designed to test whether working memory and/or auditory temporal processing can predict reading ability in normal and dyslexic readers. Fifty-three adults were diagnosed with phonological dyslexia and 46 normal reading adults were tested on reading regular words, auditory temporal order judgment, and backward digit span. The results are that: For dyslexic readers, both auditory temporal processing and working memory are correlated with reading, even after controlling for their covariance. However, no correlation between reading measures, temporal processing and working memory are found for normal readers. The conclusions are that: (1) Both auditory temporal processing and working memory are significantly involved in reading among dyslexic readers; and (2) Dyslexic readers might use more different reading strategies than normal readers do, who apparently are not involved in auditory temporal processing and working memory while reading.