The relationship between contextual facilitation and depth of processing

Two experiments examined how depth of processing on a contextual priming item affects (a) the amount of priming obtained in the processing of a target item in a lexical decision task (LDT) and (b) subsequent episodic memory for the prime and target items. Experiment 1, in which prime and target items were presented sequentially, yielded three main results: (a) The magnitude of the priming effect, measured by the difference between lexical decision times to word targets preceded by related and unrelated primes, increased as the depth of prime processing increased. (b) In an unexpected postsession recognition test, episodic memory for a prime was dependent on the depth to which it had been processed, whereas memory for a target was unaffected by the depth of processing that had occurred on its prime. (c) Episodic memory for both primes and targets was greater when they had appeared in related pairs rather than unrelated pairs in the LDT. However, unlike immediate contextual priming, the magnitude of the semantic relatedness effect in episodic recognition was not affected by level of processing. In Experiment 2 a two-word LDT was used in which a yes response was made only if two simultaneously presented letter strings were both words. Depth of processing was varied by using different types of nonword distractors: pronounceable nonwords, random letter strings, or strings of Xs. As in Experiment 1, priming was greater and episodic recognition was better, the deeper the level of processing that occurred in the LDT. Similarly, episodic recognition memory was greater for items that had appeared in related pairs in the LDT. Although these data suggest that similar processes modulate both contextual priming effects and episodic recognition, the dissociation in some conditions between the occurrence of contextual priming in the LDT and later relatedness effects in episodic recognition indicate that the underlying mechanisms are not identical.