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 recognition on 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 pr...

The studies presented in this article investigate the memory processes that underlie two phenomena in threshold identification: word superiority over pseudowords and the repetition effect (a prior presentation of an item facilitates later identification of that item). Codification (i.e., the development of a single memory code that can be triggered even by fragmented input information) explains the faster and more accurate identification of words than pseudowords. Our studies trace the development and retention of such codes for repeated pseudowords and examine the growth and loss of the repetition effect for both pseudowords and words. After approximately five prior occurrences, words and pseudowords are identified equally accurately in two types of threshold identification tasks, suggesting codification has been completed for pseudowords. Although the initial word advantage disappears, the accuracy of identification still increases with repetitions. The facilitation caused by repetition is not affected much by spacing within a session, but drops from one day to the next, and after a delay of one year has disappeared (new and old words were identified equally well). These results suggest an episodic basis for the repetition effect. Most important, after one year, performance is equal for old pseudowords and new and old words: all these levels are superior to that for new pseudowords, suggesting that the learned codes for pseudowords are as strong and permanent as the codes for words. A model of identification is presented in which feedback from codes and episodic images in memory facilitates letter processing. An instantiation of the model accounts for the major features of the data.

A gating technique was used in two studies of spoken word identification that investigated the relationship between the available acoustic-phonetic information in the speech signal and the context provided by meaningful and semantically anomalous sentences. The duration of intact spoken segments of target words and the location of these segments at the beginnings or endings of words in sentences were varied. The amount of signal duration required for word identification and the distribution of incorrect word responses were examined. Subjects were able to identify words in spoken sentences with only word-initial or only word-final acoustic-phonetic information. In meaningful sentences, less word-initial information was required to identify words than word-final information. Error analyses indicated that both acoustic-phonetic information and syntactic contextual knowledge interacted to generate the set of hypothesized word candidates used in identification. The results provide evidence that word identification is qualitatively different in meaningful sentences than in anomalous sentences or when words are presented in isolation: That is, word identification in sentences is an interactive process that makes use of several knowledge sources. In the presence of normal sentence context, the acoustic-phonetic information in the beginnings of words is particularly effective in facilitating rapid identification of words.

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