Impaired short temporal interval discrimination in a dyslexic adult

The ability to discriminate short temporal intervals was examined in a dysl exic adult (E.C.) and six matched controls. Listeners had to decide whether the second interval was shorter or longer than a standard (target) interva l. Each interval was defined as the silent duration between two successive brief tones. Eight target intervals were used, ranging from 100 to 1200 ms in duration. At each target interval, the differential threshold (DL) for d uration was assessed, with the use of an adaptive psychophysical procedure. The results show that E.C.'s differential threshold values were much large r than those of controls. Moreover, the slope estimates covering the durati on range from 100 to 800 ms indicated that in comparison to controls, E.C.' s differential threshold increased dramatically as the target duration incr eased. Thus her timing impairment becomes more pronounced with increasing d uration. This timing deficit is consistent with other studies that have fou nd temporal processing deficits associated with dyslexia. (C) 2001 Academic Press.