Understanding the role of mind wandering in stress-related working memory impairments

Mind wandering has been identified as a possible cause for stress-related working memory (WM) task impairments following laboratory stressors. The current study attempted to induce mind wandering regarding negative, positive, or neutral events using an expressive writing task and examined the impact on WM task performance. We examined the role of mind wandering in understanding the impact of life stress on WM. Additionally, we explored the role of thought suppression on the relationship between mind wandering and WM. One hundred and fifty participants completed WM measures before (Time 1) and after (Time 2) the writing manipulation. The writing manipulation did not alter mind wandering or WM task performance. Time 1 WM predicted mind wandering during the Time 2 WM task, which subsequently predicted poorer Time 2 WM task performance. The impact of daily life stress on WM was mediated by mind wandering. Trait levels of thought suppression moderated the impact of mind wandering on WM. Specifically, higher levels of suppression resulted in stronger negative impact of mind wandering on WM task performance. Findings are discussed in terms of the impact of mind wandering on WM task performance.     

RETRACTED ARTICLE: Unexpected events disrupt visuomotor working memory and increase guessing

When an unexpected event, such as a car horn honking, occurs in daily life, it often disrupts our train of thought. In the lab, this effect was recently modeled with a task in which verbal working memory (WM) was disrupted by unexpected auditory events (Wessel et al. in Nature Communications, 7, 11195, 2016). Here we tested whether this effect extends to a different type of WM—namely, visuomotor. We found that unexpected auditory events similarly decremented visuomotor WM. Moreover, this effect persisted for many more trials than had previously been shown for verbal WM, and the effect occurred for two different types of unexpected auditory events. Furthermore, we found that unexpected events decremented WM by decreasing the quantity, but not necessarily the quality, of items stored. These results showed an impact of unexpected events on visuomotor WM that was statistically robust and endured across time. They also showed that the effect was based on an increase in guessing, consistent with a neuroscience-inspired theory that unexpected events “wipe out” WM by stopping the ongoing maintenance of the trace. This new task paradigm is an excellent vehicle for further explorations of distractibility.     

The Predictive Utility of a Working Memory Span Task Depends on Processing Demand and the Cognitive Task

The relationship between performance in working memory (WM) span tasks, scholastic skills and fluid intelligence was investigated to determine how WM span is related to higher order cognition. The predictive utility of two WM span tasks differing in the demand of the processing task was studied with controlled presentation times and a broad set of academic criterion tasks. Sixty‐eight adolescents (mean age 16 years) completed two WM span tasks, Raven's Progressive Matrices and several scholastic performance measures. The results showed that the more demanding WM span task predicted fluid intelligence, but did not contribute uniquely in explaining scholastic performance. In contrast, the less demanding WM task predicted scholastic performance. The results suggest that the strength of the relation between WM performance and higher order cognition varies in conjunction with both the demand of the WM span task and the type of higher order cognition measure.Copyright © 2016 John Wiley & Sons, Ltd.     

Working memory affects false memory production for emotional events

Whereas a link between working memory (WM) and memory distortions has been demonstrated, its influence on emotional false memories is unclear. In two experiments, a verbal WM task and a false memory paradigm for negative, positive or neutral events were employed. In Experiment 1, we investigated individual differences in verbal WM and found that the interaction between valence and WM predicted false recognition, with negative and positive material protecting high WM individuals against false remembering; the beneficial effect of negative material disappeared in low WM participants. In Experiment 2, we lowered the WM capacity of half of the participants with a double task request, which led to an overall increase in false memories; furthermore, consistent with Experiment 1, the increase in negative false memories was larger than that of neutral or positive ones. It is concluded that WM plays a critical role in determining false memory production, specifically influencing the processing of negative material.     

Working-memory capacity and the control of attention: the contributions of goal neglect,response competition,and task set to Stroop interference

Individual differences in working-memory (WM) capacity predicted performance on the Stroop task in 5 experiments, indicating the importance of executive control and goal maintenance to selective attention. When the Stroop task encouraged goal neglect by including large numbers of congruent trials (RED presented in red), low WM individuals committed more errors than did high WM individuals on the rare incongruent trials (BLUE in red) that required maintaining access to the "ignore-the-word" goal for accurate responding. In contrast, in tasks with no or few congruent trials, or in high-congruency tasks that followed low-congruency tasks, WM predicted response-time interference. WM was related to latency, not accuracy, in contexts that reinforced the task goal and so minimized the difficulty of actively maintaining it. The data and a literature review suggest that Stroop interference is jointly determined by 2 mechanisms, goal maintenance and competition resolution, and that the dominance of each depends on WM capacity, as well as the task set induced by current and previous contexts.     

The persistence of thought: evidence for a role of working memory in the maintenance of task-unrelated thinking

Tasks that tax working memory (WM) have consistently been found to decrease mind wandering. These findings may indicate that maintenance of mind wandering requires WM resources, such that mind wandering cannot persist when WM resources are being consumed by a task. An alternative explanation for these findings, however, is that mind wandering persists without the support of WM but is nonetheless decreased during any demanding task because good task performance requires that attention be restricted from task-unrelated thought (TUT). The present study tested these two competing theories by investigating whether individuals with greater WM resources mind-wander more during an undemanding task, as would be predicted only by the theory that WM supports TUT. We found that individuals with higher WM capacity reported more TUT in undemanding tasks, which suggests that WM enables the maintenance of mind wandering.     

Study of behavioural and neural bases of visuo‐spatial working memory with an fMRI paradigm based on an n‐back task

The goal of this study was to propose a new functional magnetic resonance imaging (fMRI) paradigm using a language‐free adaptation of a 2‐back working memory task to avoid cultural and educational bias. We additionally provide an index of the validity of the proposed paradigm and test whether the experimental task discriminates the behavioural performances of healthy participants from those of individuals with working memory deficits. Ten healthy participants and nine patients presenting working memory (WM) deficits due to acquired brain injury (ABI) performed the developed task. To inspect whether the paradigm activates brain areas typically involved in visual working memory (VWM), brain activation of the healthy participants was assessed with fMRIs. To examine the task's capacity to discriminate behavioural data, performances of the healthy participants in the task were compared with those of ABI patients. Data were analysed with GLM‐based random effects procedures and t‐tests. We found an increase of the BOLD signal in the specialized areas of VWM. Concerning behavioural performances, healthy participants showed the predicted pattern of more hits, less omissions and a tendency for fewer false alarms, more self‐corrected responses, and faster reaction times, when compared with subjects presenting WM impairments. The results suggest that this task activates brain areas involved in VWM and discriminates behavioural performances of clinical and non‐clinical groups. It can thus be used as a research methodology for behavioural and neuroimaging studies of VWM in block‐design paradigms.     

Relational processing and working memory capacity in comprehension of relative clause sentences

Previous research has indicated that the cognitive load imposed by tasks in various content domains increases with the complexity of the relational information processed. Sentence comprehension entails processing noun-verb relations to determine who did what to whom. The difficulty of object-extracted relative clause sentences might stem from the complex noun-verb relations they entail. Across three studies, participants read 16 types of object- and subject-extracted relative clause sentences at their own pace and then responded to a comprehension question for each sentence. Relational processing was assessed using a premise integration task or a Latin square task. These tasks predicted comprehension of object-relatives before and after controlling for subject-relatives. Working memory (WM) capacity was assessed using reading span or forward and backward digit span tests. WM tasks predicted comprehension of object-relatives before but not after controlling for subject-relatives. Comprehension of object-relatives relied more heavily on a domain-general capacity to process complex relations than on WM capacity.     

Functional brain organization of working memory in adolescents varies in relation to family income and academic achievement

Working memory (WM) capacity reflects executive functions associated with performance on a wide range of cognitive tasks and education outcomes, including mathematics achievement, and is associated with dorsolateral prefrontal and parietal cortices. Here we asked if family income is associated with variation in the functional brain organization of WM capacity among adolescents, and whether that variation is associated with performance on a statewide test of academic achievement in mathematics. Participants were classified into higher‐income and lower‐income groups based on family income, and performed a WM task with a parametric manipulation of WM load (N‐back task) during functional magnetic resonance imaging (fMRI). Behaviorally, the higher‐income group had greater WM capacity and higher mathematics achievement scores. Neurally, the higher‐income group showed greater activation as a function of WM load in bilateral prefrontal, parietal, and other regions, although the lower‐income group exhibited greater activation at the lowest load. Both groups exhibited positive correlations between parietal activations and mathematics achievement scores, but only the higher‐income group exhibited a positive correlation between prefrontal activations and mathematics scores. Most of these findings were maintained when higher‐ and lower‐income groups were matched on WM task performance or nonverbal IQ. Findings indicate that the functional neural architecture of WM varies with family income and is associated with education measures of mathematics achievement.     

Hierarchical elaboration in the conceptual structures of vietnam combat veterans

Abstract

Sixty male Vietnam combat veterans, 30 hospitalized for post-traumatic stress disorder (PTSD) and 30 with no PTSD or other psychiatric disorder, sorted and labeled their life events into numeric matrices (repertory grids). Through hierarchical-classes analysis of a subject's matrix, we could compare the hierarchical level (elaboration) of the subject's constructs of a negative combat event with the hierarchical levels of other subjects' constructs of negative combat events and with the subject's precombat life event construction. As predicted, the level of construct elaboration was virtually identical for the two groups for precombat non-trauma-related events but was reduced in the PTSD group for the negative combat event. In addition, the Pythagorean distance scores of the PTSD group indicated less conceptual distance between the negative combat event and negative life events after Vietnam compared with the non-PTSD group's scores. Patients with PTSD rated negative life events more extremely (fewer “shades of gray” ratings) than did the non-PTSD group, especially life events that occurred after Vietnam.     

知觉表征精度对工作记忆中抑制干扰能力的影响

工作记忆的容量十分有限,需要选择性地抑制与目标无关信息的干扰,工作记忆容量高的个体,其抑制干扰的能力也更强。本研究采用带有不同形状干扰刺激的色块颜色回忆任务考察干扰对工作记忆容量和表征精度的影响,结果发现,当负荷超出工作记忆容量范围时,干扰减少了记忆所能表征客体的个数;当负荷在工作记忆容量范围内时,干扰降低了记忆中表征客体的精度。更进一步,研究采用独立的知觉任务来测量知觉表征的精度,并探讨作为信息加工的初始阶段的知觉表征如何影响工作记忆加工过程中抑制干扰的能力。将实验中收集的48名有效被试按照知觉表征精度的高低平均分为两组,结果发现上述干扰效应主要表现在知觉表征精度较低的组中,并且该组中知觉表征精度越高的个体,其工作记忆抑制干扰的能力也越强。本研究为实践中通过知觉训练来提升工作记忆的抑制干扰能力提供了理论指导。     

Capacity and retention capability of working memory modify the strength of the RT/IQ correlation: a short note

The limited capacity theory assumes that working memory (WM) has limited capacity to process information and, at the same time, to store other pieces of information, necessary for further processing. Quick processing of data is supposed to be the only way to solve the task without the risk of losing vital pieces of information. We predicted, then, that the correlation between mental speed, measured by reaction time (RT), and the intelligence quotient (IQ) should not appear in the case of persons who possess a relatively capacious WM store, or who show increased retention capability of their WM store. Such persons do not need to be fast, whereas, for people who show poorer indices of capacity or retention capability of WM, mental speed is the only way to tackle a complex and difficult intellectual task. As predicted, the RT/IQ correlation appeared much stronger in the group of subjects characterized by lower retention capability and capacity of WM.     

Working memory and counterexample retrieval for causal conditionals

The present study is part of recent attempts to specify the characteristics of the counterexample retrieval process during causal conditional reasoning. The study tried to pinpoint whether the retrieval of stored counterexamples (alternative causes and disabling conditions) for a causal conditional is completely automatic in nature or whether the search process also demands executive working memory (WM) resources. In Experiment 1, participants were presented with a counterexample generation task and a measure of WM capacity. We found a positive relation between search efficiency, as measured by the number of generated counterexamples in limited time, and WM capacity. Experiment 2 examined the effects of a secondary WM load on the retrieval performance. As predicted, burdening WM with an attention-demanding secondary task decreased the retrieval efficiency. Both low and high spans were affected by the WM load but load effects were less pronounced for the most strongly associated counterexamples. Findings established that in addition to an automatic search component, the counterexample retrieval draws on WM resources.     

What happens to an individual visual working memory representation when it is interrupted?

This study tested the hypothesis that even the simplest cognitive tasks require the storage of information in working memory (WM), distorting any information that was previously stored in WM. Experiment 1 tested this hypothesis by requiring observers to perform a simple letter discrimination task while they were holding a single orientation in WM. We predicted that performing the task on the interposed letter stimulus would cause the orientation memory to become less precise and more categorical compared to when the letter was absent or when it was present but could be ignored. This prediction was confirmed. Experiment 2 tested the modality specificity of this effect by replacing the visual letter discrimination task with an auditory pitch discrimination task. Unlike the interposed visual stimulus, the interposed auditory stimulus produced little or no disruption of WM, consistent with the use of modality‐specific representations. Thus, performing a simple visual discrimination task, but not a simple auditory discrimination task, distorts information about a single feature being maintained in visual WM. We suggest that the interposed task eliminates information stored within the focus of attention, leaving behind a WM representation outside the focus of attention that is relatively imprecise and categorical.     

Individuals lower in working memory capacity are particularly vulnerable to anxiety's disruptive effect on performance

Anxiety has a disruptive effect on performance in a number of domains. The purpose of this study was to determine whether individual differences in working memory (WM) capacity are related to an individual's susceptibility to anxiety's detrimental effect on performance. Fifty undergraduate students (28 females) were administered the State-Trait Anxiety Inventory (STAI) (Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1983) to measure trait anxiety and the automated operation span task to measure WM capacity (Unsworth, Heitz, Schrock, & Engle, 2005). Then, they performed a highly demanding dual-task that consisted of a primary short-term memory task and a secondary tone-discrimination task that served as a measure of spare capacity. Anxiety and WM capacity interacted to affect performance on the auditory task so that those low in WM capacity were particularly vulnerable to anxiety's disruptive effect, whereas those high in WM capacity were buffered against anxiety's effect. These findings suggest that WM capacity may be an important factor in determining which individuals underperform on anxiety-provoking tests such as scholastic achievement tests.     

Is the influence of working memory capacity on high-level cognition mediated by complexity or resource-dependent elementary processes?

The aim of this study was to investigate the involvement of working memory (WM) in elementary activities and the nature of the mechanisms mediating the influence of WM capacity on high-level cognition. We demonstrate that even elementary activities such as reading digits, subitizing small arrays of dots, or solving simple additions like 3+1 are sensitive to individual differences in WM capacity. Moreover, we demonstrate that a complex task such as counting large arrays of dots involving these elementary activities as processing steps does not induce WM-related differences beyond what can be predicted from the concatenation of differences elicited by the task’s elementary constituents. In line with the time-based resource-sharing model, these results suggest that the influence of WM capacity on high-level cognition is mediated by the impact of a basic general-purpose resource that affects each atomic step of cognition.     

Individuals lower in working memory capacity are particularly vulnerable to anxiety's disruptive effect on performance

Abstract

Anxiety has a disruptive effect on performance in a number of domains. The purpose of this study was to determine whether individual differences in working memory (WM) capacity are related to an individual's susceptibility to anxiety's detrimental effect on performance. Fifty undergraduate students (28 females) were administered the State-Trait Anxiety Inventory (STAI) (Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1983) to measure trait anxiety and the automated operation span task to measure WM capacity (Unsworth, Heitz, Schrock, & Engle, 2005). Then, they performed a highly demanding dual-task that consisted of a primary short-term memory task and a secondary tone-discrimination task that served as a measure of spare capacity. Anxiety and WM capacity interacted to affect performance on the auditory task so that those low in WM capacity were particularly vulnerable to anxiety's disruptive effect, whereas those high in WM capacity were buffered against anxiety's effect. These findings suggest that WM capacity may be an important factor in determining which individuals underperform on anxiety-provoking tests such as scholastic achievement tests.     

Aging,working memory,and discrimination learning

Older adults easily learn probabilistic relationships between cues and outcomes when the predictive event is the occurrence of a cue, but have greater difficulty when the predictive event is the nonoccurrence of a cue (Mutter & Pliske, 1996; Mutter & Plumlee, 2004; Mutter & Williams, 2004). This study explored whether this age-related deficit occurs in a simpler learning context and whether it might be related to working memory (WM) decline. We gave younger and older adults simultaneous discrimination tasks that allowed us to compare their ability to learn deterministic relationships when either the occurrence (feature positive; FP) or the nonoccurrence (feature negative; FN) of a distinctive feature predicted reinforcement. We also included a group of younger adults who performed the discrimination tasks under a concurrent WM load. Both age and WM load had a detrimental effect on initial FP and FN discrimination; however, these effects persisted only in FN discrimination after additional learning experience. Learning predictive relationships requires inductive reasoning processes that apparently do not operate as efficiently in individuals with reduced WM capacity. The impact of WM decline may ultimately be greater for negative cue–outcome relationships because learning these relationships requires more difficult inductive reasoning processes, which place greater demands on WM.     

Aging, working memory, and discrimination learning

Older adults easily learn probabilistic relationships between cues and outcomes when the predictive event is the occurrence of a cue, but have greater difficulty when the predictive event is the nonoccurrence of a cue (Mutter & Pliske, 1996; Mutter & Plumlee, 2004; Mutter & Williams, 2004). This study explored whether this age-related deficit occurs in a simpler learning context and whether it might be related to working memory (WM) decline. We gave younger and older adults simultaneous discrimination tasks that allowed us to compare their ability to learn deterministic relationships when either the occurrence (feature positive; FP) or the nonoccurrence (feature negative; FN) of a distinctive feature predicted reinforcement. We also included a group of younger adults who performed the discrimination tasks under a concurrent WM load. Both age and WM load had a detrimental effect on initial FP and FN discrimination; however, these effects persisted only in FN discrimination after additional learning experience. Learning predictive relationships requires inductive reasoning processes that apparently do not operate as efficiently in individuals with reduced WM capacity. The impact of WM decline may ultimately be greater for negative cue-outcome relationships because learning these relationships requires more difficult inductive reasoning processes, which place greater demands on WM.