Repetition Priming of Words and Nonwords in Alzheimer's Disease and Normal Aging

Objective: This study examines the magnitude and direction of nonword and word lexical decision repetition priming effects in Alzheimer's disease (AD) and normal aging, focusing specifically on the negative priming effect sometimes observed with repeated nonwords. Method: Probable AD patients (30), elderly normal controls (34), and young normal controls (49) participated in a repetition priming experiment using low-frequency words and word-like nonwords with a letter-level orthographic orienting task at study followed by a lexical decision test phase. Results: Although participants' reaction times (RTs) were longer in AD compared with elderly normal, and elderly normal compared with young normal, the repetition priming effect and the degree to which the repetition priming effect was reversed for nonwords compared to words was unaffected by AD or normal aging. Conclusion: AD patients, like young and elderly normal participants, are able to modify (in the case of words) and create (in the case of nonwords) long-term memory traces for lexical stimuli, based on a single orthographic processing trial. The nonword repetition results are discussed from the perspective of new vocabulary learning commencing with a provisional lexical memory trace created after orthographic encoding of a novel word-like letter string.