Influences of intentional and unintentional forgetting on false memories

In 2 experiments, we examined the interplay of 2 types of memory errors: forgetting and false memory--errors of omission and commission, respectively. We examined the effects of 2 manipulations known to inhibit retrieval of studied words--directed forgetting and part-list cuing--on the false recall of an unstudied "critical" word following study of its 15 strongest associates. Participants cued to forget the 1st of 2 studied lists before studying the 2nd recalled fewer List 1 words but intruded the missing critical word more often than did participants cued to remember both lists. By contrast, providing some studied words as cues during recall reduced both recall of the remaining studied words and intrusions of the critical word. The results suggest that forgetting can increase or decrease false memories, depending on whether such forgetting reflects impaired access to an entire episode or retrieval competition among elements of an episode.     

The promise and perils of self-regulated study

Self-regulated study involves many decisions, some of which people make confidently and easily (if not always optimally) and others of which are involved and difficult. Good study decisions rest on accurate monitoring of ongoing learning, a realistic mental model of how learning happens, and appropriate use of study strategies. We review our research on the decisions people make, for better or worse, when deciding what to study, how long to study, and how to study.     

Explaining retrieval-induced forgetting: A change in mental context between the study and restudy practice phases is not sufficient to cause forgetting

Retrieving information can impair the subsequent recall of related information. Such retrieval-induced forgetting is often attributed to inhibitory mechanisms, but Jonker, MacLeod, and Seli (2013) recently proposed an alternative account. In their view, the study and retrieval-practice phases constitute two disparate contexts, and impairment of unpractised members from practised categories is attributable to their being absent from the retrieval-practice context, which is where, according to Jonker et al., participants preferentially search at the time of final test. In evidence of this account, Jonker et al. showed that even restudy practice—which is assumed by the inhibitory account to be insufficient to cause forgetting (i.e., retrieval-specificity)—can cause forgetting when a mental context change is inserted between study and restudy. The present research sought to replicate this finding while also testing the possibility that a far mental context change would cause more forgetting than a near mental context change. In Experiment 1, participants described a vacation inside the United States (near) or outside the United States (far). In Experiments 2 and 3, participants described the layout of their own home (near) or their parents’ home (far). In contrast to the predictions of the context account, however, but consistent with the predictions of the inhibitory account, none of the restudy-plus-context-change conditions resulted in significant forgetting.     

Conceptual and non-conceptual repetition priming in category exemplar generation: Evidence from bilinguals

One measure of conceptual implicit memory is repetition priming in the generation of exemplars from a semantic category, but does such priming transfer across languages? That is, do the overlapping conceptual representations for translation equivalents provide a sufficient basis for such priming? In Experiment 1 (N=96) participants carried out a deep encoding task, and priming between languages was statistically reliable, but attenuated, relative to within-language priming. Experiment 2 (N=96) replicated the findings of Experiment 1 and assessed the contributions of conceptual and non-conceptual processes using a levels-of-processing manipulation. Words that underwent shallow encoding exhibited within-language, but not between-language, priming. Priming in shallow conditions cannot therefore be explained by incidental activation of the concept. Instead, part of the within-language priming effect, even under deep-encoding conditions, is due to increased availability of language-specific lemmas or phonological word forms.     

When does testing enhance retention? A distribution-based interpretation of retrieval as a memory modifier

Tests, as learning events, can enhance subsequent recall more than do additional study opportunities, even without feedback. Such advantages of testing tend to appear, however, only at long retention intervals and/or when criterion tests stress recall, rather than recognition, processes. We propose that the interaction of the benefits of testing versus restudying with final-test delay and format reflects not only that successful retrievals are more powerful learning events than are re-presentations but also that the distribution of memory strengths across items is shifted differentially by testing and restudying. The benefits of initial testing over restudying, in this view, should increase as the delay or format of the final test makes that test more difficult. Final-test difficulty, not the similarity of initial-test and final-test conditions, should determine the benefits of testing. In Experiments 1 and 2 we indeed found that initial cued-recall testing enhanced subsequent recall more than did restudying when the final test was a difficult (free-recall) test but not when it was an easier (cued-recall) test that matched the initial test. The results of Experiment 3 supported a new prediction of the distribution framework: namely, that the final cued-recall test that did not show a benefit of testing in Experiment 1 should show such a benefit when that test was made more difficult by introducing retroactive interference. Overall, our results suggest that the differential consequences of initial testing versus restudying reflect, in part, differences in how items distributions are shifted by testing and studying.     

Optimizing retrieval as a learning event: When and why expanding retrieval practice enhances long-term retention

Retrieving information from memory makes that information more recallable in the future than it otherwise would have been. Optimizing retrieval practice has been assumed, on the basis of evidence and arguments tracing back to Landauer and Bjork (1978), to require an expanding-interval schedule of successive retrievals, but recent findings suggest that expanding retrieval practice may be inferior to uniform-interval retrieval practice when memory is tested after a long retention interval. We report three experiments in which participants read educational passages and were then repeatedly tested, without feedback, after an expanding or uniform sequence of intervals. On a test 1 week later, recall was enhanced by the expanding schedule, but only when the task between successive retrievals was highly interfering with memory for the passage. These results suggest that the extent to which learners benefit from expanding retrieval practice depends on the degree to which the to-belearned information is vulnerable to forgetting.     

Conceptual and non-conceptual repetition priming in category exemplar generation: Evidence from bilinguals

One measure of conceptual implicit memory is repetition priming in the generation of exemplars from a semantic category, but does such priming transfer across languages? That is, do the overlapping conceptual representations for translation equivalents provide a sufficient basis for such priming? In Experiment 1 (N=96) participants carried out a deep encoding task, and priming between languages was statistically reliable, but attenuated, relative to within-language priming. Experiment 2 (N=96) replicated the findings of Experiment 1 and assessed the contributions of conceptual and non-conceptual processes using a levels-of-processing manipulation. Words that underwent shallow encoding exhibited within-language, but not between-language, priming. Priming in shallow conditions cannot therefore be explained by incidental activation of the concept. Instead, part of the within-language priming effect, even under deep-encoding conditions, is due to increased availability of language-specific lemmas or phonological word forms.     

Part-list cuing and the dynamics of false recall

False recall of an unpresented critical word after studying its semantic associates can be reduced substantially if the strongest and earliest-studied associates are presented as part-list cues during testing (Kimball & Bjork, 2002). To disentangle episodic and semantic contributions to this decline in false recall, we factorially manipulated the cues’ serial position and their strength of association to the critical word. Presenting cues comprising words that had been studied early in a list produced a greater reduction in false recall than did presenting words studied late in the list, independent of the cues’ associative strength, but only when recall of the cues themselves was prohibited. When recall of the cues was permitted, neither early-studied nor late-studied cues decreased false recall reliably, relative to uncued lists. The findings suggest that critical words and early-studied words share a similar fate during recall, owing to selective episodic strengthening of their associations during study.     

Thought suppression enhances memory bias for threat material

The current study examined the impact of thought suppression on indices of anxiety, including memory indices (implicit and explicit memory biases) and physiological indices (heart rate). The participants, 81 undergraduates scoring in the top quartile of a self-report measure of trait anxiety, were randomly assigned to one of three experimental groups: thought suppression (TS), thought concentration (TC), and thought wandering (TW). The TC and TW groups were included to control for the effects of effortful processing and exposure to stimuli, respectively. One block of threat words and one block of neutral words were presented under conditions of cognitive load, and participants' physiological responses and memory biases were measured. The thought suppression group exhibited an enhanced overall memory bias for threat words, driven by an elevated explicit memory bias, relative to the other two groups, a result that has implications for ironic processes theory and may inform information-processing models of anxiety.