The use of reaction time measures to evaluate nonword reading in primary progressive aphasia

We reported on a subject with nonfluent primary progressive aphasia (PPA), NL. who demonstrated an impaired ability to make rhyme judgments (Dowhaniuk , Dixon, Roy, Black, & Square, in press). Our hypothesis was that these def icits rt present a precursor to phonological alexia. However, no definitive evidence supported the existence of a phonological reading impairment as N L made relatively few errors: reading nonwords. To further evaluate NL's no nword reading, nonword and real word reaction times were compared, NL's rea ction times were significantly longer for only nonwords compared to the slo west control subject. We then assessed the first two stages of processing i nvolved in nonword reading (Coltheart, 1996). NL did not demonstrate defici ts with graphemic parsing or phoneme assignment. l-iis continuing problems with auditory rhyme judgments support the presence of a phonological proces sing deficit not specific to reading. We conclude that reaction time measur es allow for the detection of subtle nonword reading deficits. (C) 2000 Aca demic Press.