Temporal processing and reading disability

The present investigation examined the hypothesis that early auditory temporal processing deficits cause later specific reading disability by impairing phonological processing (Farmer & Klein 1995; Tallal 1980, 1984). Temporal processing ability at school entry was examined using Tallal's Repetition Test in a large unselected sample of over 500 children followed over subsequent years. Although our data confirmed the presence of certain non-speech auditory processing deficits in children later classified as specific reading-disabled, many findings were clearly at odds with a causal interpretation of this relationship. (1) Reading-disabled (RD) children were impaired at school entry on the subtest with long inter-stimulus intervals (ISIs) but not the critical short-ISI subtest. (2) RD children were not inferior to reading-age (RA) controls. (3) A subgroup of RD children with evidence of temporal deficits were no less proficient on later phonological or reading measures than RD children with no evidence of early temporal impairment. (4) Although there was a reliable concurrent correlation between temporal deficits and phonological awareness at school entry (suggesting a possible common cause explanation), early temporal deficits did not predict later phonological impairment, pseudoword processing difficulties, or specific reading disability. On the other hand, early temporal deficits did predict later oral receptive vocabulary and reading comprehension weaknesses. These findings suggest that auditory temporal deficits in dyslexies may be associated with the same dysphasic-type symptoms observed by Tallal and her colleagues in specific language-impaired populations, but do not cause the core phonological deficits that characterize dyslexic groups.