Episodic generation can cause semantic forgetting: Retrieval-induced forgetting of false memories

Memorable objects are more susceptible to forgetting: Evidence for the inhibitory account of retrieval-induced forgetting

Retrieval of target information can cause forgetting for related, but non-retrieved, information - retrieval-induced forgetting (RIF). The aim of the current studies was to examine a key prediction of the inhibitory account of RIF - interference dependence - whereby 'strong' non-retrieved items are more likely to interfere during retrieval and therefore, are more susceptible to RIF. Using visual objects allowed us to examine and contrast one index of item strength -object typicality, that is, how typical of its category an object is. Experiment 1 provided proof of concept for our variant of the recognition practice paradigm. Experiment 2 tested the prediction of the inhibitory account that the magnitude of RIF for natural visual objects would be dependent on item strength. Non-typical objects were more memorable overall than typical objects. We found that object memorability (as determined by typicality) influenced RIF with significant forgetting occurring for the memorable (non-typical), but not non-memorable (typical), objects. The current findings strongly support an inhibitory account of retrieval-induced forgetting.

True (but not false) memories are subject to retrieval-induced forgetting in children

Veridical and false memories of children aged 6 to 15 years were studied in two experiments with the retrieval-induced forgetting paradigm. Using the Deese-Roediger-McDermott (DRM) false memory word lists, children's reports of true, but not false, memories showed evidence of retrieval-induced forgetting. These differences were observed across delays as long as 2 days following word list presentation. The lack of observation of retrieval-induced forgetting in children's false memories provides evidence that a key assumption in the theory of retrieval-induced forgetting, cue independence, might not consistently apply. These experiments underscore the need for both practical and theoretically motivated study of true and false memories.

Evidence Against Associative Blocking as a Cause of Cue-Independent Retrieval-Induced Forgetting

Selectively retrieving an item from long-term memory reduces the accessibility of competing traces, a phenomenon known as retrieval-induced forgetting (RIF). RIF exhibits cue independence, or the tendency for forgetting to generalize to novel test cues, suggesting an inhibitory basis for this phenomenon. An alternative view ( Camp, Pecher, & Schmidt, 2007 ; Camp et al., 2009 ; Perfect et al., 2004 ) suggests that using novel test cues to measure cue independence actually engenders associative interference when participants covertly supplement retrieval with practiced cues that then associatively block retrieval. Accordingly, the covert-cueing hypothesis assumes that the relative strength of the practiced items at final test – and not the inhibition levied on the unpracticed items during retrieval practice – underlies cue-independent forgetting. As such, this perspective predicts that strengthening practiced items by any means, even if not via retrieval practice, should induce forgetting. Contrary to these predictions, however, we present clear evidence that cue-independent forgetting is induced by retrieval practice and not by repeated study exposures. This dissociation occurred despite significant, comparable levels of strengthening of practiced items in each case, and despite the use of Anderson and Spellman’s original (1995) independent probe method criticized by covert-cueing theorists as being especially conducive to associative blocking. These results demonstrate that cue-independent RIF is unrelated to the strengthening of practiced items, and thereby fail to support a key prediction of the covert-cueing hypothesis. The results, instead, favor a role of inhibition in resolving retrieval interference.

Golding J, Groome D. The Reliability of Retrieval-Induced Forgetting

Retrieval-induced forgetting (RIF) refers to the finding that the retrieval of an item from memory impairs the retrieval of related items. The extent to which this impairment is found in laboratory tests varies between individuals, and recent studies have reported an association between individual differences in the strength of the RIF effect and other cognitive and clinical factors. The present study investigated the reliability of these individual differences in the RIF effect. A RIF task was administered to the same individuals on two occasions (sessions T1 and T2), one week apart. For Experiments 1 and 2 the final retrieval test at each session made use of a category-cue procedure, whereas Experiment 3 employed category-plus-letter cues, and Experiment 4 used a recognition test. In Experiment 2 the same test items that were studied, practiced, and tested at T1 were also studied, practiced, and tested at T2, but for the remaining three experiments two different item sets were used at T1 and T2. A significant RIF effect was found in all four experiments. A significant correlation was found between RIF scores at T1 and T2 in Experiment 2, but for the other three experiments the correlations between RIF scores at T1 and T2 failed to reach significance. This study therefore failed to find clear evidence for reliable individual differences in RIF performance, except where the same test materials were used for both test sessions. These findings have important implications for studies involving individual differences in RIF performance.

When stereotype knowledge prevents retrieval-induced forgetting

In the present study, we examined the effects of stereotypes and the typicality of traits in retrieval-induced forgetting (RIF). The participants in the experiment practiced half of the high-typicality, low-typicality or control traits associated with the name of a stereotype (athlete, scientist) or with the name of a person (Mikel, Jon). With the person name the high-typicality, low-typicality or control traits produced no evidence of stereotype activation. The traits were processed as independent features and generated RIF both immediately and at a one-week interval. Stereotype activation during encoding facilitated the integration of high-typicality traits, avoiding RIF in immediate and one-week recall. Moreover, both high-typicality and low-typicality traits benefited from stereotypes in one-week recognition. These findings show that previous knowledge contributes to integrate stereotypic traits that would otherwise compete for retrieval, thus producing RIF.

Individual differences in the suppression of unwanted memories: the executive deficit hypothesis

When confronted with reminders to an unpleasant memory, people often try to prevent the unwanted memory from coming to mind. In this article, we review behavioral and neurocognitive evidence concerning the consequences of exerting such control over memory retrieval. This work indicates that suppressing retrieval is accomplished by control mechanisms that inhibit the unwanted memories, making them harder to recall later, even when desired. This process engages executive control mechanisms mediated by the lateral prefrontal cortex to terminate recollection-related activity in the hippocampus. Together, these findings specify a neurocognitive model of how memory control operates, suggesting that executive control may be an important means of down-regulating intrusive memories over time. We conclude by proposing that individual differences in the regulation of intrusive memories in the aftermath of trauma may be mediated by pre-existing differences in executive control ability. In support of this executive deficit hypothesis, we review the recent work indicating links between executive control ability and memory suppression.

Part-list cuing in speeded recognition and free recall

The primary question was whether part-list cuing decrements would occur in a speeded yes/no recognition task and free recall. After studying category exemplars, participants were tested either after re-presentation of a subset of the exemplars (cues) or without re-presentation. Free recall of all study items followed the recognition task in each trial. Across two experiments, results demonstrated part-list cuing impairment in two ways: significant slowing of target recognition and lower free recall of target items in cued than in uncued trials. These findings extend the limited research on part-list cuing in recognition and support retrieval inhibition and retrieval competition interpretations of the phenomenon. Moreover, despite arguments for the necessity of the presence of cues for part-list inhibition, the present experiments demonstrate that the negative effects of cues can persist in their absence.

When Remembering Causes Forgetting: Electrophysiological Correlates of Retrieval-Induced Forgetting

People tend to forget information that is related to memories they are actively trying to retrieve. On the basis of results from behavioral studies, such retrieval-induced forgetting is held to result from inhibitory control processes that are recruited to attenuate interference caused by competing memory traces. Employing electrophysiological measures of brain activity, the present study examined the neural correlates of these inhibitory processes as they operate. The results demonstrate that sustained prefrontal event-related potentials were 1) related to whether or not selective memory retrieval was required during reprocessing of previously studied words and 2) predictive of individual differences in the amount of forgetting observed in an ensuing recall test. The present findings give support to an inhibitory control account of retrieval-induced forgetting and are in accord with the view that prefrontal regions play an important role in the selection and maintenance of relevant memory representations at the expense of those currently irrelevant.

Can inhibition resolve retrieval competition through the control of spreading activation?

Two experiments are reported in which the mechanisms underlying retrieval-induced forgetting for complex prose materials were investigated, using the independent probe technique pioneered by Anderson and Spellman (1995). These experiments provide additional empirical evidence in support of an inhibitory account of memory. Specifically, evidence emerged not only for the inhibition of nonpracticed items from practiced sets (i.e., first-order effects), but also for the inhibition of items from nonpracticed sets that were semantically related to practiced items in practiced sets (i.e., cross-category effects) and for items from nonpracticed sets that were semantically related to nonpracticed items in practiced sets (ie., second-order effects). These findings are considered in terms of Anderson and Spellman's model of inhibitory processing. We also outline an alternative inhibitory interpretation. Specifically, we consider how inhibition may function as a way of controlling the spread of activation and what implications this may have for the flexibility and adaptiveness of memory.

When Remembering Causes Forgetting: Retrieval-Induced Forgetting as Recovery Failure

Retrieval practice on a subset of previously learned material can cause forgetting of the unpracticed material and make it inaccessible to consciousness. Such inaccessibility may arise because the material is no longer sampled from the set of to-be-recalled items, or, though sampled, its representation is not complete enough to be recovered into consciousness. In 2 experiments, it was examined whether retrieval-induced forgetting reflects a sampling or recovery failure by studying the time course of cued recall in this type of situation. Although retrieval practice reduced recall totals of the unpracticed items, in both experiments, the forgetting was not accompanied by an effect on the items' response latencies. This pattern of results is consistent with the view that inhibited items are successfully sampled but, because of a reduction in their activation level, do not exceed the recovery threshold.