Three studies show that the retrieval process itself causes long-lasting forgetting. Ss studied 8 categories (e.g., Fruit). Half the members of half the categories were then repeatedly practiced through retrieval tests (e.g., Fruit Or). Category-cued recall of unpracticed members of practiced categories was impaired on a delayed test. Experiments 2 and 3 identified 2 significant features of this retrieval-induced forgetting: The impairment remains when output interference is controlled, suggesting a retrieval-based suppression that endures for 20 min or more, and the impairment appears restricted to high-frequency members. Low-frequency members show little impairment, even in the presence of strong, practiced competitors that might be expected to block access to those items. These findings suggest a critical role for suppression in models of retrieval inhibition and implicate the retrieval process itself in everyday forgetting.

Previous work has shown that recalling information from long-term memory can impair the long-term retention of related representations--a phenomenon known as retrieval-induced forgetting (Anderson, Bjork, & Bjork, 1994). We report an experiment in which the question of whether retrieval is necessary to induce this form of impairment was examined. All the subjects studied six members from each of eight taxonomic categories (e.g., fruit orange). In the competitive practice condition, the subjects practiced recalling three of the six members, using category-stem cues (e.g., fruit or__). In the noncompetitive practice condition, the subjects were reexposed to these same members for the same number of repetitions but were asked to recall the category name by using the exemplar and a stem as cues (e.g., fr__orange). Despite significant and comparable facilitation of practiced items in both conditions, only the competitive practice subjects were impaired in their ability to recall the nonpracticed members on a delayed cued-recall test. These findings argue that retrieval-induced forgetting is not caused by increased competition arising from the strengthening of practiced items, but by inhibitory processes specific to the situation of recall.

The research reported herein was designed to assess whether the presence of noise elements in a visual display affects the detection of target letters at the perceptual or feature extraction level of processing, as well as at the decision level, and more specifically, whether (a) input or processing channels operate in an independent or interactive fashion and (b) how the spatial relation between signal and noise items affects detection performance. In order to distinguish among current theories proposed to account for the influence of noise items on visual processing, a forced-choice detection task was modified to incorporate a cueing procedure, which permitted the independent variation of signal-noise similarity, confusability, and proximity. The results provide evidence for feature-specific inhibition at the perceptual level, and a theory is proposed that assumes hierarchically organized, limited-capacity feature detectors and feature-specific inhibitory channels.

Kornell and Bjork (Psychological Science 19:585-592, 2008) found that interleaving exemplars of different categories enhanced inductive learning of the concepts based on those exemplars. They hypothesized that the benefit of mixing exemplars from different categories is that doing so highlights differences between the categories. Kang and Pashler (Applied Cognitive Psychology 26:97-103, 2012) obtained results consistent with this discriminative-contrast hypothesis: Interleaving enhanced inductive learning, but temporal spacing, which does not highlight category differences, did not. We further tested the discriminative-contrast hypothesis by examining the effects of interleaving and spacing, as well as their combined effects. In three experiments, using photographs of butterflies and birds as the stimuli, temporal spacing was harmful when it interrupted the juxtaposition of interleaved categories, even when total spacing was held constant, supporting the discriminative-contrast hypothesis. Temporal spacing also had value, however, when it did not interrupt discrimination processing.Keywords Categorization . Induction . Interleaving . Spacing . MetacognitionPeople accumulate a great deal of knowledge via inductive learning. Children, for example, learn concepts such as boat or fruit by being exposed to exemplars of those categories and inducing the commonalities that define the concepts.Later in life, we might learn to distinguish between different species of butterflies or birds, as in the present research. Such inductive learning is critical in making sense of events, objects, and actions-and, more generally, in structuring and understanding our world. In the present research, we examined how exemplars of to-be-learned categories should be sequenced and spaced in order to optimize inductive learning. Kornell and Bjork (2008) investigated the effect of study schedules on inductive learning-specifically, learning artists' painting styles from exemplars of their paintings. Images of six paintings by each of 12 artists were presented for study, with the artist's name displayed below each painting. The paintings by half of the artists were blocked (i.e., all six paintings by a given artist were shown consecutively), whereas the paintings by the other six artists were interleaved (i.e., mixed together). After the learning phase, participants were shown new paintings by each of the 12 artists and were asked to identify which artist had painted each new painting. Kornell and Bjork found that interleaving artists' paintings led to better performance on this inductive task than did blocking-even though participants consistently believed that blocking, rather than interleaving, had been more helpful for learning the artists' styles.

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When information is retrieved from memory, it becomes more recallable than it would have been otherwise. Other information associated with the same cue or configuration of cues, however, becomes less recallable. Such retrieval-induced forgetting (Anderson, Bjork, & Bjork, 1994) appears to reflect the suppression of competing nontarget information, with this suppression facilitating the selection of target information. But is success at such selection a necessary condition for retrieval-induced forgetting? Using a procedure in which some cues posed an impossible retrieval task for participants, we report evidence that the attempt to retrieve, even if unsuccessful, can produce retrieval-induced forgetting. This finding, we believe, supports and refines a suppression/inhibitory account of retrieval-induced forgetting.

Interleaving exemplars of to-be-learned categories-rather than blocking exemplars by category-typically enhances inductive learning. Learners, however, tend to believe the opposite, even after their own performance has benefited from interleaving. In Experiments 1 and 2, the authors examined the influence of 2 factors that they hypothesized contribute to the illusion that blocking enhances inductive learning: Namely, that (a) blocking creates a sense of fluent extraction during study of the features defining a given category, and (b) learners come to the experimental task with a pre-existing belief that blocking instruction by topic is superior to intermixing topics. In Experiments 3-5, the authors attempted to uproot learners' belief in the superiority of blocking through experience-based and theory-based debiasing techniques by (a) providing detailed theory-based information as to why blocking seems better, but is not, and (b) explicitly drawing attention to the link between study schedule and subsequent performance, both of which had only modest effects. Only when they disambiguated test performance on the 2 schedules by separating them (Experiment 6) did the combination of experience- and theory-based debiasing lead a majority of learners to appreciate interleaving. Overall, the results indicate that 3 influences combine to make altering learners' misconceptions difficult: the sense of fluency that can accompany nonoptimal modes of instruction; pre-existing beliefs learners bring to new tasks; and the willingness, even eagerness, to believe that 1 is unique as a learner-that what enhances others' learning differs from what enhances one's own learning. (PsycINFO Database Record

When presented with items that must be generated versus read at encoding, individuals typically remember better those items that they generated versus those that they only read. We examined whether--given the opportunity to experience such differential memorial consequences of generating versus reading--participants might change how they processed future to-be-read information. In a first set of two experiments, participants were able to profit from such an experience to the extent that a generation advantage was eliminated on subsequent memory tests of generated and read items. Two additional experiments demonstrated the critical nature of this experience in leading to improved processing of future to-be-read information and elimination of a generation advantage. We believe that these results relate to the characterization of the learner emerging from recent metacognitive research and have possible implications for how learners might be induced to process information more effectively.