Timing of implicit processes in aphasia: An event-related potential investigation of masked priming effects

The mechanisms responsible for anomia in aphasia are not well understood. This study explores the idea that anomia could be due to changes in the timing of automatic spreading activation in the lexical system.

Fourteen people with aphasia (PWA) and 13 control adults completed a masked priming event-related potential (ERP) task. Target words were preceded by masked, visible, or no primes and were either immediate or delayed repetitions of those primes. Prime-target intervals were varied. Analyses primarily focused on N400 effects.

PWA showed N400 priming effects for both immediate and delayed repetitions of masked primes, but control adults only showed priming effects for immediate repetitions of masked primes. Additionally, PWA's priming effects were equal for delayed repetitions of masked and visible primes while the control adults showed greater priming effects for delayed repetitions of visible than masked primes.

Findings suggest PWA experience prolonged lexical activation and might be less able to integrate implicit and explicit information than control adults.

Improved understanding of the underlying mechanisms of language impairment in aphasia will support development of more efficient, effective aphasia treatment methods.