Academic journal article Psychonomic Bulletin & Review

Strong Memories Obscure Weak Memories in Associative Recognition

Academic journal article Psychonomic Bulletin & Review

Strong Memories Obscure Weak Memories in Associative Recognition

Article excerpt

The list strength effect, in which strengthening some memories has a detrimental effect on the retrieval of other memories, has generally not been found in item recognition. The present study shows that the list strength effect does occur in associative recognition. Study materials were sets of overlapping word pairs (A-B, A-C, D-B, etc.). Within critical sets of words, strong pairs were presented three times at study, as compared with one presentation for weak pairs. In Experiment 1, associative recognition for weak pairs was less accurate than that for baseline pairs, and response times for hits were slower. In Experiment 2, receiver-operating characteristic curve data provided further evidence of poor accuracy for weak pairs. These findings support a qualitative distinction between item and associative recognition.

Do strong memories interfere with the retrieval of weaker memories? There has been little evidence for such interference in recognition memory (Murnane & Shiffrin, 1991a, 1991b; Ratcliff, Clark, & Shiffrin, 1990; Shiffrin, Huber, & Marinelli, 1995; Yonelinas, Hockley, & Murdock, 1992), with two notable exceptions. Murnane and Shiffrin (199Ib) observed a list strength effect when individual words were repeated in the context of different sentences, but not when they were repeated within identical sentences. They argued that differentcontext repetitions result in the formation of separate memory representations. This effectively increases the length of the study list in the different-context condition, and it is well-known that list length interferes with recognition. In contrast, they suggested that identical-context repetitions lead to the strengthening of a single representation and that, under these conditions, there is no list strength effect.

Norman (2002), on the other hand, did observe a list strength effect in item recognition, using identical repetitions as a means of strengthening. He failed to find a reliable effect in a second experiment but did observe a list strength effect when subjects judged whether the plurality of recognition probes had changed from study to test. Plurality discrimination has been shown to involve recollective processing (Hintzman, Curran, & Oppy, 1992; Rotello, Macmillan, & Van Tassel, 2000; Westerman, 2001). Accordingly, Norman framed his results in terms of dual-process theory: Strength-based interference affects the recollection of specific episodic or associative memory but does not affect nonspecific familiarity. The list strength effect may be elusive in recognition because the contribution of recollection is not typically isolated or controlled. The fact that only the plurality judgments produced a list strength effect in the second experiment in consistent with this conclusion.

In the present study, we were interested in associative recognition, which requires discriminating intact from rearranged word pairs. That memory for specific associations is required by the task suggests the predominant role of recollection, and this intuition is supported empirically by critical differences between associative and item recognition in time course (Dosher, 1984; Nobel & Shiffrin, 2001; Rotello & Heit, 1999, 2000), receiveroperating characteristic (ROC) curves (Rotello et al., 2000; Yonelinas, 1994,1997), and susceptibility to some manipulations (for a review, see Clark & Gronlund, 1996). If strength-based interference is specific to recollection, as is suggested by its presence in recall (Tulving & Hastie, 1972; Wixted, Ghadisha, & Vera, 1997) and plurality recognition (Norman, 2002), a list strength effect should be readily observed in associative recognition. Such a finding would lend further support to the view that item and associative recognition rely on qualitatively different retrieval processes.


The study list consisted of word pairs belonging to a number of overlapping sets. …

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