The Fate of Repetition Effects When Recognition Approaches Chance

We examined whether repetition priming effects remain above baseline when explicit recognition is reduced to chance or near chance levels by forgetting. Subjects studied a set of words, and memory was tested explicitly by yes/no (Experiments 1 & 3) or forced-choice recognition (Experiment 3) after a 20-min delay filled with an interfering task. Memory was then tested implicitly by perceptual identification (Experiment 3) or lexical decision (Experiments 1 & 2) for words seen only at study, at recognition, or both. In all experiments, recognition d' was about 0.75, and repetition effects remained above baseline and constant across conditions. At delays of 24 hr (Experiment 4) yes/no recognition fell to near chance (d' < 0.6) levels in a third of the subjects. Repetition effects as measured by lexical decision were not significantly above baseline for words seen only once in those subjects and 4 other subjects from Experiment 1 who had comparable recognition rates. Reducing recognition by forgetting to near chance levels in normal people is very difficult but when it does occur, repetition effects in normal people, in contrast with those in amnesics, are also significantly reduced or eliminated