Retrieval-induced forgetting: evidence for a recall-specific mechanism.

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 development of word retrieval abilities in the second year and its relation to early vocabulary growth.

The present research investigated the development of word retrieval abilities late in the second year when most children display a marked increase in word production. When asked what was hidden in a given box, children with still quite limited productive vocabularies were reliably less likely to produce the labels of the hidden objects than were children with larger productive vocabularies even though (1) all children could name those objects and (2) all children did well when asked to find those same hidden objects. Additionally, the provision of pictorial cues facilitated word retrieval, especially in the early stage of lexical development. Naming errors during a naturalistic book-reading session peaked in children whose productive vocabularies had recently begun to expand, further suggesting that word retrieval processes undergo significant changes at this time.

Processing instructions and the generation effect: a test of the multifactor transfer-appropriate processing theory.

We report two experiments designed to test further the multifactor transfer-appropriate processing explanation of generation effects (deWinstanley, Bjork, & Bjork, 1996). The present research focuses on the following assumptions: (a) that processing resources are limited and, thus, the processing of one type of information can be, and often is, incompatible with the processing of other types of information; and (b) that reading and generating differ in terms of the flexibility they permit for the distribution of the subject's processing resources across the available information in an experimental context. These assumptions were tested by examining the consequences of processing instructions on the occurrence of generation effects, and the lack thereof, in free recall and cued recall. Across both experiments, identical processing instructions had strikingly different consequences on the later free-recall and cued-recall performance of subjects who encoded targets by generating them versus reading them, a pattern consistent with the foregoing assumptions.

Continuing influences of to-be-forgotten information.

In the present paper, we first argue that it is critical for humans to forget; that is, to have some means of preventing out-of-date information from interfering with the recall of current information. We then argue that the primary means of accomplishing such adaptive updating of human memory is retrieval inhibition: Information that is rendered out of date by new learning becomes less retrievable, but remains at essentially full strength in memory as indexed by other measures, such as recognition and word-fragment completion. We conclude with a speculation that certain unconscious influences of prior events may, in fact, be stronger if those events were to be forgotten rather than to be remembered.

Generation effects and the lack thereof: the role of transfer-appropriate processing.

We report two experiments designed to test a multifactor transfer-appropriate processing explanation of generation effects, and the lack thereof, in free recall and cued recall. The basic argument is that the act of generating a target enhances the processing of one or more possible types of information (e.g. target-specific information, cue-target relationships, or target-target relationships) and that subsequent retention tests will reveal an advantage (or disadvantage) of such generation (compared to a "read" control) to the degree that a test is sensitive to the information on which processing was focused during study. Across the two experiments, manipulations of identical stimulus materials forced subjects to process different types of information in order to generate targets, producing a striking reversal in the relative levels of free recall and cued recall for targets that had been generated vs. read, and lending strong support to the transfer-appropriate processing aspect of the proposed framework for explaining generation effects.

Remembering can cause forgetting: retrieval dynamics in long-term memory.

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.

Letter identification in relation to linguistic context and masking conditions.

With a two-choice detection procedure, identifiability of signal letters was determined in backgrounds of words, nonword letter strings, or homogeneous noise characters. Under high performance conditions of exposure duration and pre- and postmasks, there was a substantial advantage in identifiability of letters presented alone over letters embedded in words; under low performance conditions there were generally no differences between the two types of context, but some interactive effects appeared involving particular letters with serial position and type of background. No differences were obtained between word and nonword contexts. The disparities between these findings and those reported by Reicher (1969) and Wheeler (1970) may be related to the more complete elimination under the present procedures of effects of redundancy on response selection.