Authors:

TAYLOR, J.R., WOOLLAMS, A., Karayanidis, F, BISHOP, S.J. & HENSON, R.N.A.

Reference:

Year of publication:

2007

CBU number:

6678

Abstract:

BACKGROUND: The relationship between recognition memory and repetition priming is unclear. Priming on indirect tests may be due to increased processing efficiency for repeated relative to new items. The same repetition-induced fluency likely occurs on direct tests of memory and may contribute to recognition judgments. Indeed, manipulations that increase fluency (e.g., masked repetition priming of test probes) increase the likelihood that participants will judge items to be old. This misattribution of fluency to memory affects familiarity and not recollection (i.e., it increases “know” but not “remember” judgments). To investigate the time-courses and neural sources of priming, familiarity, and recollection, we conducted an event-related potential (ERP) study of recognition memory using a remember/know paradigm with masked priming of test probes. METHODS: At Study, participants read sequentially presented words and judged whether each was interesting. At Test, studied (50%) and unstudied words were presented, each preceded by a masked prime (42 ms) that was either the probe (Primed; 50%) or a different word (Unprimed), and participants judged whether each had been studied or not (“old/new”). For items judged old, participants indicated whether they remembered (R; an index of recollection) the encoding event or simply knew (K; an index of familiarity) the item had been presented. The continuous electroencephalogram (EEG) was recorded at 21 scalp sites (with linked mastoid reference) and averaged offline. RESULTS: Masked repetition priming increased the proportion of K, but not R, responses. Priming also decreased response times for Hits but not for Correct Rejections (CRs). Four distinct ERP effects were found. A medial-frontal FN400 (300-500 ms) was sensitive to familiarity (K,R Hits > CRs) and a centro-parietal late positivity (500-800 ms) to recollection (R Hits > K Hits, CRs). A long-term repetition effect was found for items judged to be “new” (Misses > CRs) in the same time-window as the FN400, but with a posterior distribution. Finally, a centrally distributed masked priming effect (Primed > Unprimed) was visible on the P200 (150-250 ms) and continued into the 300-500 ms time-window when it was additive with the FN400 familiarity effect. Masked priming also resulted in an earlier onset of the parietal recollection effect. CONCLUSIONS: The results replicated previous findings that dissociate the cognitive and neural bases of recollection and familiarity. Additionally, the ERP data revealed dissociable effects of long- and short-term priming that were topographically distinct from recognition-related effects.