| dc.description | Much of the research in reading disabilities in recent years has concentrated on the phonological coding problems of dyslexics, and many researchers have claimed that the deficit in dyslexia is purely a phonemic, or linguistic one. However, it has been suggested (Tallal, 1984; Tallal & Curtiss, in press) that the phonemic deficit is a symptom of an underlying difficulty, that of processing rapidly occurring sequential stimuli. In this study the rapid sequential processing ability of a group of 20 adolescent dyslexics was assessed, using auditory and visual tasks. Auditory tasks (i) assessed the inter-stimulus interval required to segregate two rapidly presented clicks, (ii) required a temporal order judgment for two different-frequency tones, and (iii) involved same-different judgments for a series of long and short tones presented sequentially. Visual tasks involved (i) an assessment of the inter-stimulus interval required to segregate two rapidly presented light flashes, (ii) a temporal order judgment for two symbols, and (iii) same-different judgments for patterns of light flashes, presented simultaneously or (iv) sequentially. In addition performance on phonemic awareness tasks, and reading of both words and non-words, was assessed. The dyslexics' performance on all tasks was compared to that of both age-matched and reading-level matched normal readers of equivalent intellectual level. Results indicated qualified support for Tallal's hypothesis. Dyslexics were impaired compared to their age-matched controls on all reading and phonemic awareness tasks, on the auditory temporal order judgment task, and on the flash pattern matching task, with both sequential and simultaneous presentation. They also needed longer inter-stimulus intervals on the click fusion task, but response bias may have played a part in this result. The implications of these results for the hypothesis of a general temporal processing deficit in dyslexics, and its putative relationship to reading acquisition, are discussed, as is the possible developmental course of such a deficit in the visual and auditory modalities. | en_US |
