Episodic and lexical contributions to the repetition effect in word identification.

SUMMARY The repetition effect refers to the finding that the speed and accuracy of naming a visually presented word is enhanced by a single prior presentation of the word. A new technique was developed to study this phenomenon: The visual signal-to-noise ratio of a printed item in a field of masks was slowly increased. When accuracy was of interest, the increase ceased at a predetermined time; when latency was of interest, the increase continued until the printed item could be named. Experiment 1 tested the validity of the new accuracy technique against a more traditional threshold measure of ease of identification, in which the item is presented for a single brief exposure, followed by a mask. When performance levels at the first presentation were equated for the two techniques and for both words and nonwords, the repetition effect was equal for the techniques and slightly stronger for words than for nonwords. In Experiment la psychometric functions for first presentations were obtained, giving accuracy as a function of final exposure duration. A large interaction was seen with the traditional technique yielding superior performance for words than the new technique, but the reverse was true for nonwords. In Experiment 2 the latency version of the new technique was used: The difference in'the latencies necessary for word and nonword identification was found to be additive to the difference due to repeated presentations. Taken together, the results of the experiments suggest separate contributions of lexical status and presentations to the repetition effect. Experiment 2 used separate groups for words and nonwords, but the word-nonword difference was, if anything, increased when mixed lists of words and nonwords were used in Experiment 3. This result rules out certain guessing bias interpretations of the word-nonword differences. In Experiments 1,2, and 5, lag between repetitions had at most a small and nonsignificant effect on identification accuracy and latency. However, in Experiment 5, lag between repetitions had a large effect on rec-, ognition performance. In Experiments 1 and 3, shifting case between presentations of identical items produced a very small decrease in the repetition effect, suggesting a minimal role for low-level physical features in the repetition effect. In Experiments 2 and 4, orthographic similarity (i.e., spelling overlap) of new items to previously presented items not sharing a common morpheme was studied. A small (sometimes significant) facilitation of identification of such new items was observed. This result suggests that letter-name clusters play some role in the repetition effect. A model was developed that outlines the relative contributions of episodic traces for particular events, and of uriitized representations of words in semantic memory, to the repetition effect in word and nonword identification. The unitization that characterizes identification of words and that is missing for nonwords plays a prominent role in the model. Specifically, the repetition effect is attributed to the presence of episodic memory traces that are assumed to increase uniformly the speed and accuracy of both word