Control of the contents of working memory--a comparison of two paradigms and two age groups

Two experiments investigated whether young and old adults can temporarily remove information from a capacity-limited central component of working memory (WM) into another component, the activated part of long-term memory (LTM). Experiment 1 used a modified Sternberg recognition task (S. Sternberg, 1969); Experiment 2 used an arithmetic memory-updating task. In both paradigms, participants memorized 2 lists, one of which was cued as temporarily irrelevant. Removal of the irrelevant list from capacity-limited WM was indexed by the disappearance of list-length effects of that list on latencies for concurrent processing tasks. Young adults could outsource the irrelevant list within 2-3 s and retrieve it back into the central part of WM later. Old adults showed the same flexibility in the arithmetic updating task but seemed somewhat less able or inclined to temporarily move information into the activated part of LTM in the modified Sternberg task.     

Aging and interference in verbal working memory.

According to inhibitory views of working memory, old adults should have particular problems deleting irrelevant information from working memory, leading to greater interference effects compared with young adults. The authors investigated this hypothesis by using variations of an A-B, C-D retroactive interference paradigm in working memory with young and old adults. They used a recognition measure of memory, assessing both accuracy and reaction time. The primary finding was that senior adults consistently exhibited proportionally greater retroactive interference effects compared with young adults when interfering word pairs that had been read aloud had to be rejected. Patterns of recognition and reaction time data suggested that old adults' activation of target material is similar to young adults, but they experience sustained activation of irrelevant material that has entered working memory. Theoretical implications of these findings for inhibitory deficit (R. T. Zacks & L. Hasher, 1998) and source memory deficit accounts of cognitive aging are discussed.     

Effects of age on estimated familiarity in the process dissociation procedure: The role of noncriterial recollection

Research on recognition memory using the process dissociation procedure has suggested that although recollection (R) declines with age, familiarity (F) remains age invariant. However, this research has used relatively broad definitions of R. An important question concerns age-related changes in memory when R is defined in terms of specific event details. Yonelinas and Jacoby (1996a) required young participants to recollect specific, criterial details of a prior event and found evidence that recollection of noncriterial details elevated estimates of F yet still operated automatically. In the present study, the issue of noncriterial recollection was examined in the context of aging. The results replicated the effects of noncriterial recollection for the young, but not for the older adults, who also showed overall reduced levels of familiarity.     

Selective working memory disables inhibition of visual features

Recent research suggests that information held in working memory can facilitate subsequent attentional processing. Here, we explore the negative corollary of this conception: Under which circumstances does information in working memory disrupt subsequent processing? Seventy participants performed visual discriminations in a dual-task paradigm. They were asked to judge colors or shapes in an online attention task under three different working-memory conditions: Same, Switch, or Unknown. In the Same condition, participants selectively maintained one visual feature in working memory, from the same dimension as in the online attention task. In the Switch condition, participants selectively maintained one visual feature in working memory, but had to focus on another visual dimension in the online attention task. In the Unknown condition, participants could not predict which visual feature would be relevant for the working-memory task. We found that irrelevant features in the online attention task were particularly difficult to ignore in the Switch condition, that is, when the irrelevant features belong to a visual dimension that is simultaneously prioritized in selective working memory. The findings are consistent with accounts in terms of neural overlap between working-memory and attention circuits, and suggest that mechanisms of selection, rather than resource limitations, critically determine the extent of visual interference.     

无关负性信息对复发性抑郁缓解者工作记忆内容更新的影响

摘 要 采用改编后的Sternberg 任务考查无关负性信息对复发性抑郁缓解个体工作记忆内容更新的影响。与正常组相比,缓解期个体在无关负性条件下对探测图片的反应时要长于有关负性条件下的反应时,而正常个体在无关正性探测图片的反应时明显长于有关正性条件下的反应时。同时缓解期个体在无关负性条件下对探测图片的反应时明显长于新图条件下的反应时,出现明显的干扰效应。结果表明反复发作的抑郁缓解者在摒弃工作记忆中无关负性内容时存在障碍。     

The effect of an irrelevant dimension on “same-different” judgements of multi-dimensional stimuli

Subjects made “same”-“different” judgements of simultaneously presented pairs of visual stimuli which could vary either in shape and colour independently, or in shape alone. In both conditions only shape was relevant to the “same”-“different” judgement. In the former condition “same” and “different” reaction times (RTs) were shorter when the states (“same” or “different”) of the relevant and the irrelevant dimension, colour, were the same. This result is interpreted as support for either a perceptual or a response interference hypothesis. The presence of an irrelevant dimension did not appear to affect differentially “same” and “different” judgements. The need for a re-evaluation of the results from other studies of multi-dimensional stimulus discrimination is discussed.     

Cognitive interference and aging: insights from a spatial stimulus-response consistency task

One hundred and thirty-one adults belonging to four age groups (19-26, 50-59, 60-69 and 70-82 years) performed a spatial stimulus-response consistency task in which the response dimension (left or right) overlapped relevant and irrelevant stimulus dimensions. The influence of the irrelevant stimulus dimension on response time was significantly greater in the middle age groups than among 19-26 year-olds, and significantly greater in the highest age group than in any other. This pattern persisted when allowance was made for a significant age-related increase in processing time (measured as reaction time in a single-stimulus, single-response task). It is concluded that in tasks of the kind used, the elderly resist interference from the irrelevant information less easily than do younger persons. Interestingly, comparison of Vincentized quintiles suggested that the effect of the irrelevant stimulus dimension decreased with increasing response time among 19-26 year-olds, but increased with response time among 70-82 year-olds.     

The sufficient conditions for directed forgetting in normal and educable mentally retarded adolescents

A series of studies investigated the conditions under which normal and educable mentally retarded adolescents (13 to 15 years old) would or would not disregard irrelevant information in memory. A directed forgetting task was used in which the person was required to recall short sequences of picture names. In some sequences there was a cue to forget the first few pictures (irrelevant information) and to remember only the subsequent pictures (relevant information). When normal adolescents were given no explanation of the forget cue, there was interference from the irrelevant information. A minimum explanation of the cue, however, was sufficient to eliminate interference for the normal adolescents. The same minimal explanation was not sufficient for mentally retarded adolescents. It was clear that irrelevant information in memory interfered with the performance of retarded adolescents given only a minimal explanation of the forget cue. These results are important since most naturalistic situations do not involve an elaborate explanation of the importance of disregarding irrelevant information previously stored in memory.     

Metacognitive inferences in source memory judgements: The role of perceived differences in item recognition

This research investigated the hypothesis that metacognitive inferences in source memory judgements are based on the recognition or nonrecognition of an event together with perceived or expected differences in the recognizability of events from different sources. The hypothesis was tested with a multinomial source-monitoring model that allowed separation of source-guessing tendencies for recognized and unrecognized items. Experiments 1A and 1B manipulated the number of item presentations as relevant source information and revealed differential guessing tendencies for recognized and unrecognized items, with a bias to attribute unrecognized items to the source associated with poor item recognition. Experiments 2A and 2B replicated the findings with a manipulation of presentation time and extended the analysis to subjective differences in item recognition. Experiments 3A and 3B used more natural source information by varying type of acoustic signal and demonstrated that subjective theories about differences in item recognition are sufficient to elicit differential source-guessing biases for recognized and unrecognized items. Together the findings provide new insights into the cognitive processes underlying source memory decisions, which involve episodic memory and reconstructive tendencies based on metacognitive beliefs and general world knowledge.     

Metacognitive inferences in source memory judgements: the role of perceived differences in item recognition

This research investigated the hypothesis that metacognitive inferences in source memory judgements are based on the recognition or nonrecognition of an event together with perceived or expected differences in the recognizability of events from different sources. The hypothesis was tested with a multinomial source-monitoring model that allowed separation of source-guessing tendencies for recognized and unrecognized items. Experiments 1A and 1B manipulated the number of item presentations as relevant source information and revealed differential guessing tendencies for recognized and unrecognized items, with a bias to attribute unrecognized items to the source associated with poor item recognition. Experiments 2A and 2B replicated the findings with a manipulation of presentation time and extended the analysis to subjective differences in item recognition. Experiments 3A and 3B used more natural source information by varying type of acoustic signal and demonstrated that subjective theories about differences in item recognition are sufficient to elicit differential source-guessing biases for recognized and unrecognized items. Together the findings provide new insights into the cognitive processes underlying source memory decisions, which involve episodic memory and reconstructive tendencies based on metacognitive beliefs and general world knowledge.     

Delighted and distracted: positive affect increases priming for irrelevant information

Emotional states are known to influence how people process relevant information. Here, we address the impact of emotional state on irrelevant information. In this experiment, participants were randomly assigned to a neutral or positive mood induction, and then completed a task that involved viewing a sequence of overlapping pictures and words. They were instructed to attend to the pictures and ignore the distracting words. Following a filled interval, implicit memory for the distracting words was tested using a word fragment completion task. Individuals in the positive mood group showed increased implicit memory for previously irrelevant information compared to those in the neutral mood group. These findings are consistent with the view that positive mood broadens attention to include encoding of irrelevant information in the environment, and this can impact subsequent performance.     

Switching between filter settings reduces the efficient utilization of visual working memory

The capacity limitation of working memory requires that only relevant information gains access to the workspace, while irrelevant information is kept out. Thus, the ability to use attention to filter out irrelevant information is an important factor in how efficiently the limited storage space is used. Here, we examined to what degree the requirement to flexibly change filter settings affects filtering efficiency. Participants were presented with visual objects in different colors, and a cue presented in advance indicated which objects had to be stored. The contralateral delay activity, an event-related brain potential that reflects working-memory load was used to assess filtering efficiency during the retention interval. The data of two experiments showed that when filter settings had to be adjusted on a trial-by-trial basis, more irrelevant information passed the gate to working memory. Moreover, this switching-induced filtering deficit was restricted to those items that matched the previous, but currently irrelevant, filter settings. Thus, lingering effects of the selection history seem to counteract goal-directed encoding, and thus constitute an important attentional limitation for the efficient utilization of our limited workspace.     

Oh, it's you again: memory interference from irrelevant emotional and neutral faces

In two experiments, repeated runs of a continuous recognition task were employed to assess healthy participants' ability to handle interference from irrelevant emotional and neutral memories. Presumably, such interference can be due to salience from either emotional or mnemonic processing. In both experiments, participants made more false alarms to emotional faces that were familiar from preceding runs (i.e., emotion-induced temporal-context confusion). Participants performed well for neutral faces in the first experiment including only two runs. However, increasing the number of runs to four in the second experiment induced temporal context confusion also for neutral faces. The findings suggest that memory interference can be induced when the salience of irrelevant information is erroneously considered diagnostic for memory judgements.     

Inhibitory control over the present and the past

From the perspective of the Hasher, Zacks, and May (1999) inhibitory framework, optimal performance occurs only when there is control over nonrelevant information. Relative to a current, goal-directed task, there are at least two potential sources of nonrelevant information that need to be controlled. The first is no longer relevant information. Such information would include, for example, a previous topic of conversation, or, in our work, a previous list of materials presented for study and recall. The second source of nonrelevant information is currently present (in thought or in the world) stimuli that are not relevant to the task at hand. Inhibitory processes are critical to the effective control of both sources of information?the no longer relevant past and the irrelevant present. If inhibitory processes are inefficient, irrelevant information from both the past and the present will disrupt performance on the current task. We illustrate this with studies showing the role of irrelevant information in reducing the working memory capacity of older adults and in slowing them down as they do even reasonably simple tasks.     

Saving-enhanced performance: saving items after study boosts performance in subsequent cognitively demanding tasks

ABSTRACT

By saving and storing information, we use digital devices as our external memory stores, being able to offload and temporarily forget saved contents. Storm and Stone [2015. Saving-enhanced memory: The benefits of saving on the learning and remembering of new information. Psychological Science, 26(2), 182–188] showed that such memory offloading can be beneficial for subsequent memory performance. Saving already encoded items enhanced recall of items encoded after saving. In the present study, we did not only replicate saving-enhanced memory but found saving-enhanced performance for unrelated cognitively demanding tasks. Participants solved more modular arithmetic problems when they were able to offload a previously studied word list, compared to trials without the possibility to offload. Thus, saving of recently encoded items entailed a general benefit on subsequent cognitive performance, beyond encoding and retrieving word lists. We assume that offloading frees participants from the need to maintain offloaded items. Gained resources can then be used for subsequent tasks with high cognitive demands. In a nutshell, memory offloading can help to reduce the amount of information that has to be processed at a given time, efficiently delegating our limited cognitive resources to the most relevant tasks at hand while currently irrelevant information are safely stored outside our own memory.     

The phonological loop model of working memory: An ERP study of irrelevant speech and phonological similarity effects

The phonological loop model for retention of auditory verbal material in working memory, developed by Baddeley, assumes that irrelevant speech and phonological similarity influence only one and the same element of the system—that is, the phonological short-term store. We tested this idea by recording eventrelated potentials (ERPs) to auditorily presented letters that were phonologically similar or dissimilar and were to be memorized in the presence of more or less disturbing irrelevant speech. Irrelevant speech and phonological similarity caused ERP effects with clearly different scalp topographies, indicating that these factors influence different brain systems and hence probably different cognitive elements. Moreover, ERPs indicated that the phonological similarity effect might involve processes at the level of phonological analysis. Our data also support recent suggestions that the irrelevant speech effect is not based on the phonological similarity between relevant and irrelevant material, but on the phonological variability within the irrelevant stream.     

Processing irrelevant location information: Practice and transfer effects in choice-reaction tasks

Left or right keypresses to a relevant stimulus dimension are faster when the stimulus location, although irrelevant, corresponds with that of the response than when it does not. This phenomenon, called the Simon effect, persisted across 1,800 trials of practice, although its magnitude was reduced. Practice with the relevant stimulus dimension presented at a centered location had little influence on the magnitude of the Simon effect when irrelevant location was varied subsequently, and practice with location irrelevant prior to performing with location relevant slowed responses. After practice responding to stimulus location with an incompatible spatial mapping, the Simon effect was reversed (i.e., responses were slower when stimulus location corresponded with response location) when location was made irrelevant. When the response keys were labeled according to the relevant stimulus dimension (the Hedge and Marsh [1975] task variation), this reversal from practice with a spatially incompatible mapping was found for both the congruent and the incongruent relevant stimulus-response mappings. Thus, task-defined associations between stimulus location and response location affect performance when location is changed from relevant to irrelevant, apparently through producing automatic activation of the previously associated response.     

Interference by process, not content, determines semantic auditory distraction

Distraction by irrelevant background sound of visually-based cognitive tasks illustrates the vulnerability of attentional selectivity across modalities. Four experiments centred on auditory distraction during tests of memory for visually-presented semantic information. Meaningful irrelevant speech disrupted the free recall of semantic category-exemplars more than meaningless irrelevant sound (Experiment 1). This effect was exacerbated when the irrelevant speech was semantically related to the to-be-remembered material (Experiment 2). Importantly, however, these effects of meaningfulness and semantic relatedness were shown to arise only when instructions emphasized recall by category rather than by serial order (Experiments 3 and 4). The results favor a process-oriented, rather than a structural, approach to the breakdown of attentional selectivity and forgetting: performance is impaired by the similarity of process brought to bear on the relevant and irrelevant material, not the similarity in item content.     

The size of the Simon effect depends on the nature of the relevant task

Four experiments were conducted to investigate contextual modulations of the Simon effect. The results showed that the Simon effect was quantitatively different depending on which kind of task needed to be performed. Importantly, this effect did not depend on the relative processing time of the relevant dimension, nor on a direct or indirect overlap between the relevant and irrelevant stimulus part. To account for the data, we refer to the neural overlap hypothesis, which extends the definition of dimensional overlap (Kornblum, Hasbroucq, & Osman, 1990) with similarity of processing regions as the key factor for the interaction between relevant and irrelevant information processing.     

Cue-type manipulation dissociates two types of task set inhibition: backward inhibition and competitor rule suppression

Backward inhibition (BI) reflects the suppression of a recently abandoned task set to allow for smooth transition to a new task even when the rules do not generate a response conflict. Competitor rule suppression (CRS) reflects the inhibition/suppression of irrelevant task rules when these rules generate a response conflict even if they have not recently been abandoned. We assessed whether BI and CRS are differentially affected by the difficulty in retrieving category-response mappings from memory. Retrieval demands were manipulated via the information provided by the task cues, which either indicated the relevant dimension (dimension cues; “color”) or the relevant dimension with its category-to-key mapping (mapping cues; “red green”, indicating that “red” and “green” go with the left/right responses, respectively). CRS was larger with dimension compared to mapping cues when cue-type varied between groups and was larger after trials involving dimension cues when cue-type varied on a trial-by-trial basis. In contrast, BI was not influenced by cue-type. These results suggest that task switching involve at least two distinct inhibitory processes, with CRS being related to the ease of retrieval of category-response mappings from memory.