Retrieval-mediated directed forgetting in the item-method paradigm: the effect of semantic cues

How varying cue duration influences item-method directed forgetting: A novel selective retrieval interpretation

A series of four experiments tested the assumptions of the most prominent and longstanding account of item-method directed forgetting: the selective rehearsal account. In the item-method directed forgetting paradigm, each presented item is followed by its own instructional cue during the study phase - either to-be-forgotten (F) or to-be-remembered (R). On a subsequent test, memory is poorer for F items than for R items. To clarify the mechanism underlying memory performance, we manipulated the time available for rehearsal, examining instructional cue durations of 1 s, 5 s, and 10 s. Experiments 1a and 1b, where the order of cue durations was randomized, showed no effect of cue duration on item recognition of unrelated single words, for either R or F items. Experiment 2, using unrelated word pairs, again showed no effect of randomized cue duration, this time on associative recognition. Experiments 3 and 4 blocked cue duration and showed equivalent increases in recognition of both R and F single words and word pairs with increasing cue duration. We suggest that any post-cue rehearsal is carried out only when cue duration is predictable, and that such limited rehearsal is equally likely for F items and R items. The consistently better memory for R items than for F items across cue duration depends on selective retrieval involving (1) a rapid retrieval check engaged for R items only and (2) a rapid removal process implemented for F items only.

Separation of item and context in item-method directed forgetting

Contextual information plays a critical role in directed forgetting (DF) of lists of items, whereas DF of individual items has been primarily associated with item-level processing. This study was designed to investigate whether context processing also contributes to the forgetting of individual items. Participants first viewed a series of words, with task-irrelevant scene images (used as "context tags") interspersed between them. Later, these words reappeared without the scenes and were followed by an instruction to remember or forget that word. Multivariate pattern analyses of fMRI data revealed that the reactivation of context information associated with the studied words (i.e., scene-related activity) was greater whereas the item-related information diminished after a forget instruction compared to a remember instruction. Critically, we found the magnitude of the separation between item information and context information predicted successful forgetting. These results suggest that the unbinding of an item from its context may support the intention to forget, and more generally they establish that contextual processing indeed contributes to item-method DF.

A novel paradigm to assess storage of sources in memory: the source recognition test with reinstatement

The present research aimed to devise a test of source recognition that facilitates access to source information stored in memory. Therefore, we extended the standard source-monitoring paradigm, in which items are presented in a source-neutral manner during test, by a second, subsequent test with source reinstatement. In this second test, items (i.e., words) were presented with both study sources (i.e., two speakers) consecutively such that for originally studied words, one test presentation was the exact reinstatement of the original source. To validate our assumption that the test with reinstatement primarily assesses source storage, we manipulated source storage by varying encoding frequency between-participants (repetition vs. no repetition of each item-source-pair). Additionally, we varied source similarity between-participants (similar vs. dissimilar speakers). Data analyses (N = 146) based on multinomial and signal detection models showed a source memory enhancement in the second test with reinstatement compared to the first standard test, especially for similar sources. Additionally, repetition selectively benefited source memory in the second test, validating our interpretation of the second test as a measure for source storage. Altogether, our novel source recognition test offers a promising method for investigating various well-known source memory phenomena more comprehensively.

Forgetting under difficult conditions: Item-method directed forgetting under perceptual processing constraints

Intentional forgetting of unwanted items is effortful, yet directed forgetting seems to improve when a secondary task is performed. According to the cognitive load hypothesis of directed forgetting, allocating attentional resources to another task improves forgetting by restricting unwanted encoding of to-be-forgotten (TBF) items. Alternatively, it might be that anything that makes studying more difficult will encourage greater effort to perform the task well and therefore lead to improved intentional forgetting. To assess these proposals we imposed data-processing limitations on study words in an item-method directed forgetting paradigm. Across six experiments, the perceptual quality of study words was manipulated by varying: (1) the duration of study word presentation (Experiments 1-4); (2) the contrast of the displayed word against its visual background (Experiment 5); or (3) the amount of visual background noise on which the word was presented (Experiment 6). In Experiments 4-6, a lexical decision task corroborated the difficulty of study word processing. Despite evidence that relatively low visual contrast and relatively high visual background noise, in particular, create challenging conditions, we found no evidence that perceptual quality impacts the magnitude of the directed forgetting effect. This work suggests that data limitations have no discernible effect on forgetting and corroborate that only attentional resource limitations improve directed forgetting.