Perceptual Thresholds and Priming in Amnesia

The widely accepted idea that perceptual priming is intact in amnesia was challenged recently by the suggestion that perceptual identification (PID) thresholds are elevated in amnesia and that this impairment could mask a priming deficit by artificially inflating priming scores. The authors examined the PID thresholds of amnesic patients across a wide range of stimulus conditions and accuracy levels. Baseline thresholds and priming effects were fully intact for all amnesic patients except in a condition using small stimuli (1.1° x 0.25° of visual angle). In that condition, only the patients with Korsakoff's syndrome were impaired. Accordingly, elevated perceptual thresholds are not a necessary consequence of amnesia, and normal priming in amnesia is not an artifact of threshold differences. The results support the conclusion that priming is independent of the brain structures important for declarative memory that are damaged in amnesia.