The present research aimed at identifying cognitive processing that works at the initial stage of letter identification. First, we used the word superiority effect task to set the baseline of visual detection rate and then we used the letter matching task to evaluate the phonemic transference rate of the particpants. It was hypothesized that physically-different letters required longer processing time as the judgment depended not only on visual detection, but also on a process of phonemic transference. Our results found that the control group had a higher letter identification rate than the dyslexic group, showing that visual detection rate was a good predictor of reading disability. However, phonemic transference rate was not a good predictor of dyslexia. One of the reasons may be that the process of letter identification involved cognitive skills other than that of phonemic transference alone.