Interference In Working Memory Research Articles

Subthalamic nucleus deep brain stimulation affects distractor interference in auditory working memory

Computational and theoretical accounts hypothesize the basal ganglia play a supramodal “gating” role in the maintenance of working memory representations, especially in preservation from distractor interference. There are currently two major limitations to this account. The first is that supporting experiments have focused exclusively on the visuospatial domain, leaving questions as to whether such “gating” is domain-specific. The second is that current evidence relies on correlational measures, as it is extremely difficult to causally and reversibly manipulate subcortical structures in humans. To address these shortcomings, we examined non-spatial, auditory working memory performance during reversible modulation of the basal ganglia, an approach afforded by deep brain stimulation of the subthalamic nucleus. We found that subthalamic nucleus stimulation impaired auditory working memory performance, specifically in the group tested in the presence of distractors, even though the distractors were predictable and completely irrelevant to the encoding of the task stimuli. This study provides key causal evidence that the basal ganglia act as a supramodal filter in working memory processes, further adding to our growing understanding of their role in cognition.

Individual differences in proactive interference in verbal and visuospatial working memory

ABSTRACTProactive interference (PI) has been shown to affect working memory (WM) span as well as the predictive utility of WM span measures. However, most of the research on PI has been conducted using verbal memory items, and much less is known about the role of PI in the visuospatial domain. In order to further explore this issue, the present study used a within-subjects manipulation of PI that alternated clusters of trials with verbal and visuospatial to-be-remembered items. Although PI was shown to build and release across trials similarly in the two domains, important differences also were observed. The ability of verbal WM to predict performance on a measure of fluid intelligence was significantly affected by the amount of PI present, consistent with past research, but this proved not to be the case for visuospatial WM. Further, individuals’ susceptibility to PI in one domain was relatively independent of their susceptibility in the other domain, suggesting that, contrary to some theories of executive function, individual differences in PI susceptibility may not be domain-general.

Stress and Cognitive Flexibility: Cortisol Increases Are Associated with Enhanced Updating but Impaired Switching.

Acute stress has frequently been shown to impair cognitive flexibility. Most studies have examined the effect of stress on cognitive flexibility by measuring how stress changes performance in paradigms that require participants to switch between different task demands. These processes typically implicate pFC function, a region known to be impaired by stress. However, cognitive flexibility is a multifaceted construct. Another dimension of flexibility, updating to incorporate relevant information, involves the dorsal striatum. Function in this region has been shown to be enhanced by stress. Using a within-subject design, we tested whether updating flexibility in a DMS task would be enhanced by an acute stress manipulation (cold pressor task). Participants' cortisol response to stress positively correlated with a relative increase in accuracy on updating flexibility (compared with trials with no working memory interference). In contrast, in line with earlier studies, cortisol responses correlated with worse performance when switching between trials with different task demands. These results demonstrate that stress-related increases in cortisol are associated with both increases and decreases in cognitive flexibility, depending on task demands.

Visuospatial working memory influences the interaction between space and time.

How do representations of space inform our perception of time? In language, spatial vocabulary is frequently used to describe temporal concepts, and spatial information biases temporal perception even in non-verbal tasks. In contrast, temporal information typically exerts little, if any, influence on the perception of spatial extent. Here, we used spatial and temporal reproduction tasks, both with and without verbal and spatial dual tasks, to investigate the mechanism underlying the asymmetric relation between space and time. Specifically, we tested whether the asymmetric interference between spatial and temporal stimulus attributes arises from interference in verbal or visuospatial working memory. We found that loading visuospatial working memory, but not verbal working memory, eliminated the asymmetric pattern of interference. This suggests that the interference between spatial and temporal representations arises due to processing constraints in visuospatial working memory. These findings are discussed in terms of the load theory of attention and the relative automaticity with which spatial and temporal information is processed.

Contrasting single and multi-component working-memory systems in dual tasking

Working memory can be a major source of interference in dual tasking. However, there is no consensus on whether this interference is the result of a single working memory bottleneck, or of interactions between different working memory components that together form a complete working-memory system. We report a behavioral and an fMRI dataset in which working memory requirements are manipulated during multitasking. We show that a computational cognitive model that assumes a distributed version of working memory accounts for both behavioral and neuroimaging data better than a model that takes a more centralized approach. The model’s working memory consists of an attentional focus, declarative memory, and a subvocalized rehearsal mechanism. Thus, the data and model favor an account where working memory interference in dual tasking is the result of interactions between different resources that together form a working-memory system.

Visuospatial Working Memory Capacity Predicts Physiological Arousal in a Narrative Task.

Physiological arousal that occurs during narrative production is thought to reflect emotional processing and cognitive effort (Bar-Haim et al. in Dev Psychobiol 44:238-249, 2004). The purpose of this study was to determine whether individual differences in visuospatial working memory and/or verbal working memory capacity predict physiological arousal in a narrative task. Visuospatial working memory was a significant predictor of skin conductance level (SCL); verbal working memory was not. When visuospatial working memory interference was imposed, visuospatial working memory was no longer a significant predictor of SCL. Visuospatial interference also resulted in a significant reduction in SCL. Furthermore, listener ratings of narrative quality were contingent upon the visuospatial working memory resources of the narrator. Potential implications for educators and clinical practitioners are discussed.

Overwriting and intrusion in short-term memory.

Studies of interference in working and short-term memory suggest that irrelevant information may overwrite the contents of memory or intrude into memory. While some previous studies have reported greater interference when irrelevant information is similar to the contents of memory than when it is dissimilar, other studies have reported greater interference for dissimilar distractors than for similar distractors. In the present study, we find the latter effect in a paradigm that uses auditory tones as stimuli. We suggest that the effects of distractor similarity to memory contents are mediated by the type of information held in memory, particularly the complexity or simplicity of information.

Stereotype threat, mental arithmetic, and the mere effort account

The currently prevailing explanation for stereotype threat (ST) debilitation effects argues for working memory interference as the proximal mediator. Using mental arithmetic problems as the test bed, Beilock et al. (2007) have spelled out in greater detail exactly how this process might work. They propose that worries resulting from activation of the negative stereotype occupy the phonological loop, taking up capacity that could be used to remember the intermediate values produced when solving horizontal mental subtraction problems. In the current work, we test an alternative, motivational account for this effect, mere effort. The mere effort account argues that ST motivates stigmatized participants to want to perform well, potentiating the prepotent response on the given task. In Experiment 1 we identified a possible prepotent response for horizontal subtraction, termed the method of adjustment (e.g., adjust the second number to the nearest 10, subtract the two numbers, and then add the adjustment). Consistent with the mere effort account, Experiment 2 showed that ST potentiated the prepotent approach, the method of adjustment. Experiment 3 pitted the mere effort account against the working memory account. Working memory predicts debilitation effects on horizontal subtraction problems when participants need to use the phonological loop (i.e., entering answers from left-to-right), whereas mere effort predicts that the potentiated use of the method of adjustment should facilitate performance when answers must be entered from left-to-right. Results supported the mere effort account. Finally, Experiment 4 showed that when we control for the effect of the potentiated prepotent response, instead of performing more poorly, threatened participants perform better than no threat participants. Overall, these experiments support the mere effort account, which argues for motivation as a core process in producing ST effects.

Performance of a Sonification Task in the Presence of Verbal, Visuospatial, and Auditory Interference Tasks

An experiment examined performance with sonifications—a general term for nonspeech auditory displays—as a function of working memory encoding and the demands of three different types of interference tasks. Participants encoded the sonifications as verbal representations, visuospatial images, or auditory images. After encoding, participants engaged in brief verbal, visuospatial, or auditory interference tasks before responding to point estimation queries about the sonifications. Results were expected to show selective impact on sonification task performance when the interference task demands matched the working memory encoding strategy, but instead a pattern of general working memory interference emerged in addition to auditory modal interference. In practical applications, results suggested that performance with auditory displays will be impacted by any interference task, though auditory tasks likely will cause more interference than verbal or visuospatial tasks.

Mechanisms of distractor interference in visual working memory

Mechanisms of distractor interference in visual working memory

Spatial-simultaneous working memory and selective interference in Down syndrome

Several studies have suggested that individuals with Down syndrome (DS) have impairments in some aspects of the visuospatial domain. It has been reported that they are particularly impaired in the spatial-simultaneous working memory (WM) even in advantageous conditions such as when information is grouped to form a configuration. This study aimed to assess the performance of individuals with DS carrying out a spatial-simultaneous WM task in single and dual selective interference conditions in order to better explore the characteristics of their impairment in this area.Groups of individuals with DS and mentally age-matched typically developing (TD) children were asked to carry out a spatial-simultaneous WM task in a single- and in two dual-task conditions. In the single condition, the participants were required to recall an increasing number of positions of red squares presented simultaneously in a matrix. In the dual-task conditions, together with the spatial-simultaneous WM task, the participants were asked to carry out an articulatory suppression task or a tapping task.As has already been shown in other studies, individuals with DS were found to be impaired in carrying out a spatial-simultaneous WM task and showed a worse performance with respect to the TD group in both the conditions.These findings indicate that individuals with DS use the same coding modality as TD children of the same mental age. Just as the TD children, they performed lower in the dual- than in the single-task condition and there was no difference between the verbal and visuospatial conditions.

What Is the Role of Tone in the Phonological Similarity Effect?

To recall a list of phonologically similar words is more difficult than to recall a list of phonologically dissimilar words; this is the well-known phonological similarity effect in verbal working memory. However, it is hypothesized that not all phonological aspects of a word would create the phonological similarity interference in verbal working memory. The present study examines the influence of different phonological characteristics of the to-be-memorized items on participants’ recall performance. Convergent results from two experiments revealed the phonological similarity effect was less evident with same tone materials. These results are discussed in terms of the role of tone in the phonological similarity effect in verbal working memory.

Executive dysfunction in patients with temporal lobe epilepsy and its correlation with P300

To explore the changes of executive function in patients with temporal lobe epilepsy and analyze its correlation with P300 event-related potentials. Fifty patients with temporal lobe epilepsy and 30 age, gender and education-matched healthy control subjects were assessed by neuropsychological tests, including Montreal cognitive assessment (MoCA), working memory, verbal fluency, trail making, digit span, digit symbol and Stroop color-word interference to detect P300 event-related potentials. In temporal lobe epilepsy group, the scores in MoCA, verbal and non-verbal working memory, verbal fluency, digit span, digit symbol and Stroop test were lower than those of the normal control group. And trail making tests A and B became prolonged (P < 0.05). Comparing with normal control group, temporal lobe epilepsy patients had prolonged latency [(332 ± 33)ms] and decreased P300 amplitude [(10 ± 8)µV] (P < 0.05). Comparing epileptogenic focus group on the left and right sides, there was statistically significant difference in verbal working memory (P < 0.05). There was a negative correlation of P300 latency and MoCA, non-verbal working memory, digit span and digit symbol test scores (r = -0.29--0.45, P < 0.05). And a positive correlation of P300 amplitude and MoCA, non-verbal working memory, digit symbol conversion and Stroop scores was also found (r = 0.37-0.47, P < 0.05). P300 amplitude was more relevant to overall cognitive level and executive functions. Temporal lobe is involved in the regulation of executive functions. Besides a wide range of cognitive impairment, temporal lobe epilepsy patients have a number of executive dysfunctions, including working memory, cognitive flexibility, attention and inhibitory control ability. And an impairment of verbal working memory is evident in left-sided lesion. Their manifestations include decreased latency and amplitude of P300 on executive function tests. Therefore these two objective parameters may be employed to evaluate the cognitive impairment in patients with temporal lobe epilepsy.

Lending a Hand to Imagery? The Impact of Visuospatial Working Memory Interference Upon Iconic Gesture Production in a Narrative Task

Visuospatial working memory is thought to be responsible for imagery generation (Cattaneo et al. in Imagery and spatial cognition: methods, models and cognitive assessment, John Benjamins Publishing Company, Amsterdam, 2006). This memory system was manipulated by varying visual perceptual input (see Baddeley and Andrade in Theories of memory, Psychology Press, Hove, 1998) in a narrative task in order to investigate the association between iconic gesture production and visuospatial working memory interference. Participants watched two short cartoon clips and were asked to relay a narrative about what they had seen in the videos to an experimenter. Participants were randomly assigned to relay their narrative while wearing video glasses with either a simple or complex moving image (unrelated to the cartoons) projected onto the lenses. It was hypothesized that if gesture production plays a role in facilitating visuospatial working memory resource activation, then participants in the complex visual distractor condition would display a higher rate of gesture production. Participants in the complex visual distractor condition gestured significantly more than participants in the simple visual distractor condition. These results are interpreted as lending support to the argument that iconic gestures may play a functional role in activating visuospatial working memory resources during a narrative task. Since visuospatial working memory is thought to support imagery, these results also suggest that gesture production may facilitate imagery generation.

Comparable mechanisms of working memory interference by auditory and visual motion in youth and aging

Intrasensory interference during visual working memory (WM) maintenance by object stimuli (such as faces and scenes), has been shown to negatively impact WM performance, with greater detrimental impacts of interference observed in aging. Here we assessed age-related impacts by intrasensory WM interference from lower-level stimulus features such as visual and auditory motion stimuli. We consistently found that interference in the form of ignored distractions and secondary task interruptions presented during a WM maintenance period, degraded memory accuracy in both the visual and auditory domain. However, in contrast to prior studies assessing WM for visual object stimuli, feature-based interference effects were not observed to be significantly greater in older adults. Analyses of neural oscillations in the alpha frequency band further revealed preserved mechanisms of interference processing in terms of post-stimulus alpha suppression, which was observed maximally for secondary task interruptions in visual and auditory modalities in both younger and older adults. These results suggest that age-related sensitivity of WM to interference may be limited to complex object stimuli, at least at low WM loads.

Early Prefrontal Activation As a Mechanism to Prevent Forgetting in the Context of Interference

Recent research has focused on interference resolution deficits as the main cause of short-term memory decreases in aging. To determine whether activation of brain compensatory mechanisms occur during the encoding process in older people. Moreover, two different levels of interference (distraction and interruption) were presented during the maintenance period to examine how they modulate brain activity profiles. A delayed match-to-sample task with two experimental conditions: distraction and interruption. Twenty-seven young adults from Complutense University of Madrid and 20 healthy older adults from Complutense Elderly University of Madrid. Magnetoencephalography scans were recorded during the execution of a working memory interference task. Brain activity sources from younger and older adults during the encoding stage were compared in each condition using minimum norm estimation analyses. The elderly showed enhancement of prefrontal activity during early latencies of the encoding process in both conditions. In the distraction condition, enhanced activity was located in left ventrolateral prefrontal regions, whereas in the interruption condition, enhanced activity was observed in the right ventral prefrontal areas and anterior cingulate cortex. Increased recruitment of prefrontal regions in the elderly might be related to the processing depth of information, encoding of new information and semantic associations that are successfully recalled, and with interference resolution and preparatory control when the level of interference becomes higher. These prefrontal modulations during early latencies might reflect a higher top-down control of the encoding process in normal aging to prevent forgetting.

Anticipation and the control of voluntary action

Anticipation and the control of voluntary action

Prefrontal inhibition of threat processing reduces working memory interference

Bottom-up processes can interrupt ongoing cognitive processing in order to adaptively respond to emotional stimuli of high potential significance, such as those that threaten wellbeing. However it is vital that this interference can be modulated in certain contexts to focus on current tasks. Deficits in the ability to maintain the appropriate balance between cognitive and emotional demands can severely impact on day-to-day activities. This fMRI study examined this interaction between threat processing and cognition; 18 adult participants performed a visuospatial working memory (WM) task with two load conditions, in the presence and absence of anxiety induction by threat of electric shock. Threat of shock interfered with performance in the low cognitive load condition; however interference was eradicated under high load, consistent with engagement of emotion regulation mechanisms. Under low load the amygdala showed significant activation to threat of shock that was modulated by high cognitive load. A directed top-down control contrast identified two regions associated with top-down control; ventrolateral PFC and dorsal ACC. Dynamic causal modeling provided further evidence that under high cognitive load, top-down inhibition is exerted on the amygdala and its outputs to prefrontal regions. Additionally, we hypothesized that individual differences in a separate, non-emotional top-down control task would predict the recruitment of dorsal ACC and ventrolateral PFC during top-down control of threat. Consistent with this, performance on a separate dichotic listening task predicted dorsal ACC and ventrolateral PFC activation during high WM load under threat of shock, though activation in these regions did not directly correlate with WM performance. Together, the findings suggest that under high cognitive load and threat, top-down control is exerted by dACC and vlPFC to inhibit threat processing, thus enabling WM performance without threat-related interference.

Pornographic Picture Processing Interferes with Working Memory Performance

Some individuals report problems during and after Internet sex engagement, such as missing sleep and forgetting appointments, which are associated with negative life consequences. One mechanism potentially leading to these kinds of problems is that sexual arousal during Internet sex might interfere with working memory (WM) capacity, resulting in a neglect of relevant environmental information and therefore disadvantageous decision making. In this study, 28 healthy individuals performed 4 experimental manipulations of a pictorial 4-back WM task with neutral, negative, positive, or pornographic stimuli. Participants also rated 100 pornographic pictures with respect to sexual arousal and indicated masturbation urges previous to and following pornographic picture presentation. Results revealed worse WM performance in the pornographic picture condition of the 4-back task compared with the three remaining picture conditions. Furthermore, hierarchical regression analysis indicated an explanation of variance of the sensitivity in the pornographic picture condition by the subjective rating of the pornographic pictures as well as by a moderation effect of masturbation urges. Results contribute to the view that indicators of sexual arousal due to pornographic picture processing interfere with WM performance. Findings are discussed with respect to Internet sex addiction because WM interference by addiction-related cues is well known from substance dependencies.

A broken filter: Prefrontal functional connectivity abnormalities in schizophrenia during working memory interference

Characterizing working memory (WM) abnormalities represents a fundamental challenge in schizophrenia research given the impact of cognitive deficits on life outcome in patients. In prior work we demonstrated that dorsolateral prefrontal cortex (DLPFC) activation was related to successful distracter resistance during WM in healthy controls, but not in schizophrenia. Although understanding the impact of regional functional deficits is critical, functional connectivity abnormalities among nodes within WM networks may constitute a final common pathway for WM impairment. Therefore, this study tested the hypothesis that schizophrenia is associated with functional connectivity abnormalities within DLPFC networks during distraction conditions in WM. 28 patients and 24 controls completed a delayed non-verbal WM task that included transient visual distraction during the WM maintenance phase. We computed DLPFC whole-brain task-based functional connectivity (tb-fcMRI) specifically during the maintenance phase in the presence or absence of distraction. Results revealed that patients failed to modulate tb-fcMRI during distracter presentation in both cortical and sub-cortical regions. Specifically, controls demonstrated reductions in tb-fcMRI between DLPFC and the extended amygdala when distraction was present. Conversely, patients failed to demonstrate a change in coupling with the amygdala, but showed greater connectivity with medio-dorsal thalamus. While controls showed more positive coupling between DLPFC and other prefrontal cortical regions during distracter presentation, patients failed to exhibit such a modulation. Taken together, these findings support the notion that observed distracter resistance deficit involves a breakdown in coupling between DLPFC and distributed regions, encompassing both subcortical (thalamic/limbic) and control region connectivity.