Replication and extension of long-term implicit memory: Perceptual priming but conceptual cessation

We endeavored to replicate Mitchell's (2006) finding of 17-year implicit memory priming. Subjects saw word and picture stimuli in 1999-2000 (M age = 18.9) and were retested after 11-14 years (M = 13.2; M age = 32.1). Via the internet, they completed four implicit memory tasks: picture fragment identification, word fragment completion, word stem completion, and category exemplar generation. Relative to control subjects (matched on stimuli, age, and education), longitudinal subjects revealed priming on picture and word fragment identification (perceptual tasks), but no priming on word stem completion or category exemplar generation (conceptual tasks). Four longitudinal subjects who failed to recall participating in the prior laboratory session had priming similar to the 10 subjects who did remember. Thus, we replicated the longevity of perceptual priming for pictures, and extended this to word fragment priming as well.