Age differences in the neural response to emotional distraction during working memory encoding

Age-related declines in attention and working memory (WM) are well documented and may be worsened by the occurrence of distracting information. Emotionally valenced stimuli may have particularly strong distracting effects on cognition. We investigated age-related differences in emotional distraction using task-fMRI. WM performance in older adults was lower for emotional compared with neutral distractors, suggesting a disproportional impairment elicited by emotional task-irrelevant information. Critically, older adults were particularly distracted by task-irrelevant positive information, whereas the opposite pattern was found for younger adults. Age groups differed markedly in the brain response to emotional distractors; younger adults activated posterior cortical regions and the striatum, and older adults activated frontal regions. Also, an age by valence interaction was found for IFG and ACC, suggesting differential modulation of attention to task-relevant emotional information. These results provide new insights into age-related changes in emotional processing and the ability to resolve interference from emotional distraction.     

A facilitative effect of negative affective valence on working memory

Gotoh, F., Kikuchi, T. &Olofsson, U. (2010). A facilitative effect of negative affective valence on working memory. Scandinavian Journal of Psychology, 51, 185–191. Previous studies have shown that negatively valenced information impaired working memory performance due to an attention‐capturing effect. The present study examined whether negative valence could also facilitate working memory. Affective words (negative, neutral, positive) were used as retro‐cues in a working memory task that required participants to remember colors at different spatial locations on a computer screen. Following the cue, a target detection task was used to either shift attention to a different location or keep attention at the same location as the retro‐cue. Finally, participants were required to discriminate the cued color from a set of distractors. It was found that negative cues yielded shorter response times (RTs) in the attention‐shift condition and longer RTs in the attention‐stay condition, compared with neutral and positive cues. The results suggest that negative affective valence may enhance working memory performance (RTs), provided that attention can be disengaged.     

Heterogeneity of auditory verbal working memory in schizophrenia

The heterogeneity of schizophrenia remains an obstacle for understanding its pathophysiology. Studies using a tone discrimination screening test to classify patients have found evidence for 2 subgroups having either a specific deficit in verbal working memory (WM) or deficits in both verbal and nonverbal memory. This study aimed to (a) replicate in larger samples differences between these subgroups in auditory verbal WM; (b) evaluate their performance on tests of explicit memory and sustained attention; (c) determine the relation of verbal WM deficits to auditory hallucinations and other symptoms; and (d) examine medication effects. The verbal WM and tone discrimination performance did not differ between medicated (n = 45) and unmedicated (n = 38) patients. Patients with schizophrenia who passed the tone screening test (discriminators; n = 60) were compared with those who did not (nondiscriminators; n = 23) and healthy controls (n = 47). The discriminator subgroup showed poorer verbal WM than did controls and a deficit in verbal but not visual memory on the Wechsler Memory Scale-Revised (Wechsler, 1987), whereas the nondiscriminator subgroup showed overall poorer performance on both verbal and nonverbal tests and a marked deficit in sustained attention. Verbal WM deficits in discriminators were correlated with auditory hallucinations but not with negative symptoms. The results are consistent with a verbal memory deficit in a subgroup of schizophrenia having intact auditory perception, which may stem from dysfunction of language-related cortical regions, and a more generalized cognitive deficit in a subgroup having auditory perceptual and attentional dysfunction.     

The impact of object working memory on timing

Nontemporal information processing involving short-term memory requirements disturbs time estimation. Previous studies mostly used letters or digits, which are maintained in working memory by phonological loops. Since verbal and nonverbal information are processed by separate working-memory subsystems, how do nonverbal, object-based memory tasks affect time estimation? We manipulated visual object memory load using the magic cube materials. Participants were divided into three groups, who completed a reaction-time task (control task), a memory-recognition task interposed by an attempt to produce a 2500-ms time interval (active processing), and a memory-recognition task following time interval production (passive retention). The produced time increased with increasing memory-object size under both the active processing and passive retention conditions; mean produced time interval did not significantly differ between the two experimental conditions. By comparing the reaction times and error rates of a relevant task, we excluded any speed–accuracy tradeoff during timing. This result suggests that when the working-memory information to be processed includes objects requiring attention for retention, the production of time intervals is also affected by memory item maintenance.     

Intact attentional control of working memory encoding in schizophrenia

This study reports evidence that individuals with schizophrenia (SC) demonstrate intact attentional selection for visual working memory (WM) storage. A group of 62 participants with SC and 55 control participants without SC were studied in a series of 5 experiments that examined the ability to use top-down and bottom-up cues to guide WM encoding, as well as the ability to spontaneously select a subset of representations for storage. Participants with SC exhibited a consistent and robust ability to use selective attention in the control of WM in all 5 experiments, demonstrating a remarkable island of preserved functioning given the broad spectrum of impairments of attention and WM that have been widely reported in those with SC. These findings indicate that attention is not globally impaired in SC and make it possible to delineate more precisely the nature of the specific impairment of attention in this disorder.     

The impact of achievement goal states on working memory

The present study examines the influence of achievement goal states on working memory under varying executive load. Seventy-six undergraduate students were randomly assigned to either a mastery-approach condition (goal was to develop self-referential competence), a performance-approach condition (goal was to demonstrate normative competence) or a control condition (no goal assigned) prior to completing the N-Back working memory task. Analyses revealed achievement goal effects on working memory under high executive load (3-back) but not under the less demanding loads (1-back, 2-back). Under high load, pursuit of a performance-approach goal resulted in poorer working memory processing than pursuit of a mastery-approach goal or no-goal control. Findings are unlikely to be confounded by cognitive ability, working memory capacity or state-anxiety. Contributions to the motivation–cognition interface and suggestions for future research are discussed.     

Syntactic working memory and the establishment of filler-gap dependencies: insights from ERPs and fMRI

In this contribution, we review an ERP experiment and an fMRI experiment which investigated the processing of German wh-questions. On the basis of the ERP results, we will discuss current models of sentence processing and resource distribution during sentence comprehension. We argue that there exists a separate cognitive or neural resource that supports syntactic working memory processes necessary for the temporary maintenance of syntactic information for the parser. In the context of wh-movement, such a memory component is necessary for establishing filler-gap dependencies. The data obtained from the fMRI experiment will be used to discuss the results of previous neuroimaging studies of sentence processing. It is claimed that syntactic working memory, rather than syntactic processing per se, is supported by Broca's Area.     

Processing spatial-temporal information in recent-onset schizophrenia: the study of short-term memory and its susceptibility to distraction

Memory impairment is a core feature in schizophrenia (SZ). The aim of this study was to investigate short-term memory (STM) and its sensitivity to distraction with visual-spatial material. This study comprised 23 recent-onset SZ patients and 23 healthy controls. The degree of disruption upon recall from interleaving irrelevant items within a sequence of to-be-remembered items-the sandwich effect [Hitch, G. J. (1975). The role of attention in visual and auditory suffix effects. Memory and Cognition, 3, 501-505]-was examined. STM performance, whether in the presence or absence of distraction, was poorer and markedly more vulnerable to disruption in SZ. Our results suggest that processing spatial information in STM is susceptible to interference in SZ.     

Clearing the mind: a working memory model of distraction from negative mood

The present research examined whether and how loading working memory can attenuate negative mood. In three experiments, participants were exposed to neutral, weakly negative, or strongly negative pictures followed by a task and a mood scale. Working memory demands were varied by manipulating task presence (Study 1), complexity (Study 2), and predictability (Study 3). Participants in all three experiments reported less negative moods in negative trials with high compared to low working memory demand. Working memory demands did not affect mood in the neutral trials. When working memory demands were high, participants no longer reported more negative moods in response to strongly negative pictures than to weakly negative pictures. These findings suggest that loading working memory prevents mood-congruent processing, and thereby promotes distraction from negative moods.     

Bottom-up influences on working memory: behavioral and electrophysiological distraction varies with distractor strength

The present study investigates bottom-up effects serving the optimal balance between focusing attention on relevant information and distractibility by potentially significant events outside the focus of attention. We tested whether distraction, indicated by behavioral and event-related brain potential (ERP) measures, varies with the strength of task-irrelevant deviances. Twenty subjects performed a tone-duration discrimination task (200 or 400 ms sinusoidal tones presented equiprobably). The stimuli were presented with frequent standard (p = 0.84; 1000 Hz) or infrequent deviant (p = 0.16) pitch. These task-irrelevant pitch changes consisted in a frequency increase/decrease of 1%, 3%, 5%, or 10%. Each of them resulted in prolonged reaction times (RT) in the duration discrimination task and elicited the MMN, P3a, and RON components of the ERP. Importantly, these measures did increase as a function of pitch deviance. Separating the individual trials on the 1% deviation level into trials with and without RT prolongation, i.e., behavioral distraction effect, revealed that both subgroups had similar MMN, but P3a and RON were confined to the trials with RT prolongation. Results are interpreted within a model relating preattentive deviance detection, distraction, and working memory.     

On the waxing and waning of working memory: action orientation moderates the impact of demanding relationship primes on working memory capacity

The present research examined how action- versus state-oriented individuals (Kuhl & Beckmann, 1994) utilize their working memory capacity under varying situational demands. Participants visualized either a demanding or an accepting person, after which their working memory capacity was assessed. Among action-oriented participants, visualizing a demanding person led to greater operation spans (Study 1) and superior memory for intention-related information (Study 2) than visualizing an accepting person. State-oriented participants displayed the opposite pattern, such that visualizing an accepting person led to greater operation spans (Study 1) and superior memory for intentions (Study 2) than visualizing a demanding person. These findings indicate that action versus state orientation moderates the impact of situational demands on working memory capacity.     

Cognitive-behavioral and electrophysiological evidence of the affective consequences of ignoring stimulus representations in working memory

Ignoring visual stimuli in the external environment leads to decreased liking of those items, a phenomenon attributed to the affective consequences of attentional inhibition. Here we investigated the generality of this “distractor devaluation” phenomenon by asking whether ignoring stimuli represented internally within visual working memory has the same affective consequences. In two experiments we presented participants with two or three visual stimuli and then, after the stimuli were no longer visible, provided an attentional cue indicating which item in memory was the target they would have to later recall, and which were task-irrelevant distractors. Participants subsequently judged how much they liked these stimuli. Previously-ignored distractors were consistently rated less favorably than targets, replicating prior findings of distractor devaluation. To gain converging evidence, in Experiment 2, we also examined the electrophysiological processes associated with devaluation by measuring individual differences in attention (N2pc) and working memory (CDA) event-related potentials following the attention cue. Larger amplitude of an N2pc-like component was associated with greater devaluation, suggesting that individuals displaying more effective selection of memory targets—an act aided by distractor inhibition—displayed greater levels of distractor devaluation. Individuals showing a larger post-cue CDA amplitude (but not pre-cue CDA amplitude) also showed greater distractor devaluation, supporting prior evidence that visual working-memory resources have a functional role in effecting devaluation. Together, these findings demonstrate that ignoring working-memory representations has affective consequences, and adds to the growing evidence that the contribution of selective-attention mechanisms to a wide range of human thoughts and behaviors leads to devaluation.     

Performance of schizophrenia and bipolar patients on verbal and figural working memory tasks

Working memory (WM) was studied in 82 healthy volunteers, 43 schizophrenia patients, and 81 bipolar patients. Schizophrenia patients were impaired on verbal and figural WM tasks that possessed similar test discriminating power. Bipolar patients performed similarly to healthy volunteers. A mathematical model of WM performance revealed a primary role for reduced WM span in accounting for the impaired verbal WM of schizophrenia patients and a primary role for diminished attention in accounting for impaired figural WM. Although WM impairment in schizophrenia is due neither to the general effects of severe mental illness nor to the specific type of material studied, the microarchitecture of abnormal WM in schizophrenia may depend on the stimulus material presented.     

Using perceptrons to explore the reorientation task

The reorientation task is a paradigm that has been used extensively to study the types of information used by humans and animals to navigate in their environment. In this task, subjects are reinforced for going to a particular location in an arena that is typically rectangular in shape. The subject then has to find that location again after being disoriented, and possibly after changes have been made to the arena. This task is used to determine the geometric and featural cues that can be used to reorient the agent in the arena. The purpose of the present paper is to present several simulation results that show that a simple neural network, a perceptron, can be used to generate many of the traditional findings that have been obtained using the reorientation task. These results suggest that reorientation task regularities can be explained without appealing to a geometric module that is a component of spatial processing.     

Using a modified lag task to measure adult age differences in working memory

Four groups of adults, ages 40 to 70+ years, took the Modified Lag Task which requires that participants remember lists of words and subsequently recall the first, second, or third word from the end of the list. Previously, the task showed convergent validity with the operation span (a complex span measure) and a divergent validity with the digit span (a simple span measure). To establish predictive validity, the present study was designed to assess if this task could separate four age groups in working memory performance. The present study found support for the validity of the Modified Lag Task; however, additional research is warranted to further develop the construct validity of this task.     

Understanding age-related reductions in visual working memory capacity: Examining the stages of change detection

Visual working memory (VWM) capacity is reduced in older adults. Research has shown age-related impairments to VWM encoding, but aging is likely to affect multiple stages of VWM. In the present study, we recorded the event-related potentials (ERPs) of younger and older adults during VWM maintenance and retrieval. We measured encoding-stage processing with the P1 component, maintenance-stage processing with the contralateral delay activity (CDA), and retrieval-stage processing by comparing the activity for old and new items (old–new effect). Older adults showed lower behavioral capacity estimates (K) than did younger adults, but surprisingly, their P1 components and CDAs were comparable to those of younger adults. This remarkable dissociation between neural activity and behavior in the older adults indicated that the P1 and CDA did not accurately assess their VWM capacity. However, the neural activity evoked during VWM retrieval yielded results that helped clarify the age-related differences. During retrieval, younger adults showed early old–new effects in frontal and occipital areas and a late central–parietal old–new effect, whereas older adults showed a late right-lateralized parietal old–new effect. The younger adults’ early old–new effects strongly resembled an index of perceptual fluency, suggesting that perceptual implicit memory was activated. The activation of implicit memory could have facilitated the younger adults’ behavior, and the lack of these early effects in older adults may suggest that they have much lower-resolution memory than do younger adults. From these data, we speculated that younger and older adults store the same number of items in VWM, but that younger adults store a higher-resolution representation than do older adults.     

Introduction to the special issue on visual working memory

Visual working memory is a volatile, limited-capacity memory that appears to play an important role in our impression of a visual world that is continuous in time. It also mediates between the contents of the mind and the contents of that visual world. Research on visual working memory has become increasingly prominent in recent years. The articles in this special issue of Attention, Perception, & Psychophysics describe new empirical findings and theoretical understandings of the topic.     

High working memory capacity does not always attenuate distraction: Bayesian evidence in support of the null hypothesis

Individual differences in working memory capacity (WMC) predict individual differences in basically all tasks that demand some form of cognitive labor, especially if the persons conducting the task are exposed to distraction. As such, tasks that measure WMC are very useful tools in individual-differences research. However, the predictive power of those tasks, combined with conventional statistical tools that cannot support the null hypothesis, also makes it difficult to study the limits of that power. In this article, we review studies that have failed to find a relationship between WMC and effects of auditory distraction on visual–verbal cognitive performance, and use meta-analytic Bayesian statistics to test the null hypothesis. The results favor the assumption that individual differences in WMC are, in fact, not (always) related to the magnitude of distraction. Implications for the nature of WMC are discussed.     

Investigating the impact of mindfulness meditation training on working memory: A mathematical modeling approach

We investigated whether mindfulness training (MT) influences information processing in a working memory task with complex visual stimuli. Participants were tested before (T1) and after (T2) participation in an intensive one-month MT retreat, and their performance was compared with that of an age- and education-matched control group. Accuracy did not differ across groups at either time point. Response times were faster and significantly less variable in the MT versus the control group at T2. Since these results could be due to changes in mnemonic processes, speed–accuracy trade-off, or nondecisional factors (e.g., motor execution), we used a mathematical modeling approach to disentangle these factors. The EZ-diffusion model (Wagenmakers, van der Maas, & Grasman, Psychonomic Bulletin & Review 14:(1), 3–22, 2007) suggested that MT leads to improved information quality and reduced response conservativeness, with no changes in nondecisional factors. The noisy exemplar model further suggested that the increase in information quality reflected a decrease in encoding noise and not an increase in forgetting. Thus, mathematical modeling may help clarify the mechanisms by which MT produces salutary effects on performance.     

Selective attention to elements in working memory

Three experiments with an arithmetic working memory task examine the object switch effect first reported by Garavan (1998), which was interpreted as evidence for a focus of attention within working memory. Experiments 1a and 1b showed object switch costs with a task that requires selective access to items in working memory, but did not involve counting, and did not require updating of working memory contents, thus ruling out two alternative explanations of Garavan's results. Experiment 2 showed object switch costs with a task that required no selective access to working memory contents, but involved updating, thus providing evidence for a second component to the overall object switch costs. Further analyses revealed that the object switch cost increased with memory set size; that there were (smaller) switch costs when the switch was to an item of the same type; that repeating an arithmetic operation does not have the same effect as repeating the object it is applied to; and that object switching is not mediated by backward inhibition of the previously focused object.