Increased Task Demands Research Articles

Age differences in BOLD modulation to task difficulty as a function of amyloid burden.

Effective cognitive performance often requires the allocation of additional neural resources (i.e. blood-oxygen-level-dependent [BOLD] activation) as task demands increase, and this demand-related modulation is affected by amyloid-beta deposition and normal aging. The present study investigated these complex relationships between amyloid, modulation, and cognitive function (i.e. fluid ability). Participants from the Dallas Lifespan Brain Study (DLBS, n = 252, ages 50-89) completed a semantic judgment task during functional magnetic resonance imaging (fMRI) where the judgments differed in classification difficulty. Amyloid burden was assessed via positron emission tomography (PET) using 18F-florbetapir. A quadratic relationship between amyloid standardized value uptake ratios (SUVRs) and BOLD modulation was observed such that modulation was weaker in those with moderately elevated SUVRs (e.g. just reaching amyloid-positivity), whereas those with very high SUVRs (e.g. SUVR > 1.5) showed strong modulation. Greater modulation was related to better fluid ability, and this relationship was strongest in younger participants and those with lower amyloid burden. These results support the theory that effective demand-related modulation contributes to healthy cognitive aging, especially in the transition from middle age to older adulthood, whereas high modulation may be dysfunctional in those with substantial amyloid deposition.

Registered report: Age-preserved semantic memory and the CRUNCH effect manifested as differential semantic control networks: An fMRI study.

Semantic memory representations are generally well maintained in aging, whereas semantic control is thought to be more affected. To explain this phenomenon, this study tested the predictions of the Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH), focusing on task demands in aging as a possible framework. The CRUNCH effect would manifest itself in semantic tasks through a compensatory increase in neural activation in semantic control network regions but only up to a certain threshold of task demands. This study compares 39 younger (20-35 years old) with 39 older participants (60-75 years old) in a triad-based semantic judgment task performed in an fMRI scanner while manipulating task demand levels (low versus high) through semantic distance. In line with the CRUNCH predictions, differences in neurofunctional activation and behavioral performance (accuracy and response times) were expected in younger versus older participants in the low- versus high-demand conditions, which should be manifested in semantic control Regions of Interest (ROIs). Our older participants had intact behavioral performance, as proposed in the literature for semantic memory tasks (maintained accuracy and slower response times (RTs)). Age-invariant behavioral performance in the older group compared to the younger one is necessary to test the CRUNCH predictions. The older adults were also characterized by high cognitive reserve, as our neuropsychological tests showed. Our behavioral results confirmed that our task successfully manipulated task demands: error rates, RTs and perceived difficulty increased with increasing task demands in both age groups. We did not find an interaction between age group and task demand, or a statistically significant difference in activation between the low- and high-demand conditions for either RTs or accuracy. As for brain activation, we did not find the expected age group by task demand interaction, or a significant main effect of task demand. Overall, our results are compatible with some neural activation in the semantic network and the semantic control network, largely in frontotemporoparietal regions. ROI analyses demonstrated significant effects (but no interactions) of task demand in the left and right inferior frontal gyrus, the left posterior middle temporal gyrus, the posterior inferior temporal gyrus and the prefrontal gyrus. Overall, our test did not confirm the CRUNCH predictions.

Investigating the role of flight phase and task difficulty on low-time pilot performance, gaze dynamics and subjective situation awareness during simulated flight.

Gaze behaviour has been used as a proxy for information processing capabilities that underlie complex skill performance in real-world domains such as aviation. These processes are highly influenced by task requirements, expertise and can provide insight into situation awareness (SA). Little research has been done to examine the extent to which gaze behaviour, task performance and SA are impacted by various task manipulations within the confines of early-stage skill development. Accordingly, the current study aimed to understand the impact of task difficulty on landing performance, gaze behaviour and SA across different phases of flight. Twenty-four low-time (<300 hours) pilots completed simulated landing scenarios under visual flight rules conditions. Traditional gaze metrics, entropybased metrics, and blink rate provided meaningful insight about the extent to which information processing is modulated by flight phase and task difficulty. The results also suggested that gaze behavior changes compensated for increased task demands and minimized the impact on task performance. Dynamic gaze analyses were shown to be a robust measure of task difficulty and pilot flight hours. Recommendations for the effective implementation of gaze behaviour metrics and their utility in examining information processing changes are discussed.

Mental Workload Classification and Tasks Detection in Multitasking: Deep Learning Insights from EEG Study.

While the term task load (TL) refers to external task demands, the amount of work, or the number of tasks to be performed, mental workload (MWL) refers to the individual's effort, mental capacity, or cognitive resources utilized while performing a task. MWL in multitasking scenarios is often closely linked with the quantity of tasks a person is handling within a given timeframe. In this study, we challenge this hypothesis from the perspective of electroencephalography (EEG) using a deep learning approach. We conducted an EEG experiment with 50 participants performing NASA Multi-Attribute Task Battery II (MATB-II) under 4 different task load levels. We designed a convolutional neural network (CNN) to help with two distinct classification tasks. In one setting, the CNN was used to classify EEG segments based on their task load level. In another setting, the same CNN architecture was trained again to detect the presence of individual MATB-II subtasks. Results show that, while the model successfully learns to detect whether a particular subtask is active in a given segment (i.e., to differentiate between different subtasks-related EEG patterns), it struggles to differentiate between the two highest levels of task load (i.e., to distinguish MWL-related EEG patterns). We speculate that the challenge comes from two factors: first, the experiment was designed in a way that these two highest levels differed only in the quantity of work within a given timeframe; and second, the participants' effective adaptation to increased task demands, as evidenced by low error rates. Consequently, this indicates that under such conditions in multitasking, EEG may not reflect distinct enough patterns to differentiate higher levels of task load.

Impaired motor inhibition during perceptual inhibition in older, but not younger adults: a psychophysiological study

The prefrontal cortex (PFC) governs the ability to rapidly cancel planned movements when no longer appropriate (motor inhibition) and ignore distracting stimuli (perceptual inhibition). It is unclear to what extent these processes interact, and how they are impacted by age. The interplay between perceptual and motor inhibition was investigated using a Flanker Task, a Stop Signal Task and a combined Stop Signal Flanker Task in healthy young (n = 33, Mean = 24 years) and older adults (n = 32, Mean = 71 years). PFC activity was measured with functional near-infrared spectroscopy (fNIRS), while electromyography (EMG) measured muscle activity in the fingers used to respond to the visual cues. Perceptual inhibition (the degree to which incongruent flankers slowed response time to a central cue) and motor inhibition (the speed of cancellation of EMG activation following stop cues) independently declined with age. When both processes were engaged together, PFC activity increased for both age groups, however only older adults exhibited slower motor inhibition. The results indicate that cortical upregulation was sufficient to compensate for the increased task demands in younger but not older adults, suggesting potential resource sharing and neural limitations particularly in older adults.

Dynamic reconfiguration of brain coactivation states that underlying working memory correlates with cognitive decline in clinically unimpaired older adults.

Impairments in working memory (WM) are evident in both clinically diagnosed patients with mild cognitive decline and older adults at risk, as indicated by lower scores on neuropsychological tests. Examining the WM-related neural signatures in at-risk older adults becomes essential for timely intervention. WM functioning relies on dynamic brain activities, particularly within the frontoparietal system. However, it remains unclear whether the cognitive decline would be reflected in the decreased dynamic reconfiguration of brain coactivation states during WM tasks. We enrolled 47 older adults and assessed their cognitive function using the Montreal Cognitive Assessment. The temporal dynamics of brain coactivations during a WM task were investigated through graph-based time-frame modularity analysis. Four primary recurring states emerged: two task-positive states with positive activity in the frontoparietal system (dorsal attention and central executive); two task-negative states with positive activity in the default mode network accompanied by negative activity in the frontoparietal networks. Heightened WM load was associated with increased flexibility of the frontoparietal networks, but the cognitive decline was correlated with reduced capacity for neuroplastic changes in response to increased task demands. These findings advance our understanding of aberrant brain reconfiguration linked to cognitive decline, potentially aiding early identification of at-risk individuals.

Eye Movement Correlates of Working Memory Capacity: Evidence from the Reading Span Task

In reading, eye movements are typically influenced by both higher-level and lower-level cognitive processes that are affected by individual differences such as working memory capacity. However, the extent to which working memory impacts reading under increasing task demands remains uncertain. Therefore, this study aimed to explore the influence of working memory capacity, assessed via the n-back task, on peak saccade velocity during reading when an additional memory task is introduced. Thirty-one healthy participants with normal or corrected-to-normal vision read sentences performing either comprehension task or dual task on comprehension and working memory span. The results of the comprehension task were used as a baseline to track the differences in eye movement measures in the dual task with the increasing task demand. Participants who performed well in the n-back task exhibited higher peak saccade velocity during both single and dual reading tasks, particularly as the task demands increased: reading for comprehension while simultaneously maintaining six items in working memory was associated with the highest peak saccade velocity. Conversely, those with n-back lower performance did not display significant changes in peak saccade velocity. This discrepancy is attributed to task-induced variations in arousal among high-performing individuals. The study underscores the importance of individual differences in working memory and suggests a potential link between arousal and cognitive processes involved in reading comprehension.

Lower extremity joint contact force symmetry during walking and running, 2-7 years post-ACL reconstruction.

Premature osteoarthritis after anterior cruciate ligament reconstruction (ACLR) is common among athletes. Reduced knee contact forces after ACLR likely contribute to the multifactorial etiology of the disease. Whether this reduction is accompanied by compensatory increases in joint contact forces (JCF) at adjacent or contralateral joints is unclear. It is also unclear if compensatory effects depend on the task demands. Thus, we compared hip, knee, and ankle JCF symmetry between individuals with reconstruction and a matched control group during walking and running. Thirty participants (19 females), 2-7 years post-unilateral ACLR (mean = 47.8 months), and 30 controls matched on sex, mass, and activity level were recruited. Limb symmetry indices of peak contact forces and force impulses were calculated for each joint during walking and running, and analyzed using two-factor (group, activity) analysis of variances. Lower ACLR group peak knee JCF (p = 0.009) and knee JCF impulse (p = 0.034) during walking and running were observed. An interaction of group and activity was observed for peak hip JCF, with ACLR participants demonstrating greater involved limb peak hip JCF during running (p = 0.012). Ankle JCF and ground reaction force symmetry indices were not different between groups or across tasks. Decreased knee and increased ipsilateral peak hip JCF during running suggests that proximal adaptations exist at 2-7 years after ACLR, particularly during activities with increased task demand. Clinical significance: Knee and hip JCF asymmetry at 2-7 years after ACLR may underscore a need for clinical strategies and follow-up assessments to identify and target such outcomes.

How do students learn with real‐time personalized scaffolds?

AbstractScaffolds that support self‐regulated learning (SRL) have been found to improve learning outcomes. The effects of scaffolds can differ depending on how learners use them and how specific scaffolds might influence learning processes differently. Personalized scaffolds have been proposed to be more beneficial for learning due to their adaptivity to learning progress and individualized content to learning needs. The present study investigated finer‐grained effects of how personalized scaffolds driven by a rule‐based artificial intelligence system influenced SRL processes, especially how students learned with them. Using a pre‐post experimental design, we investigated personalized scaffolds based on university students' real‐time learning processes in a technologically enhanced learning environment. Students in the experimental group (n = 30) received personalized scaffolds, while the control group (n = 29) learned without scaffolds. All students completed a 45‐minute learning task with trace data recorded. Findings indicated scaffold effects on students' subsequent learning behaviour. Additionally, only scaffold interaction correlated to essay performance and suggests that the increase in frequencies of SRL activities alone does not contribute directly to learning outcomes. As guidelines for real‐time SRL support are lacking, this study provides valuable insights to enhance SRL support with adaptive learning technologies. Practitioner notesWhat is already known about this topic Self‐regulated learning scaffolds, especially adaptive scaffolds, improve learning. Personalized scaffolds have effects on self‐regulated learning activities. Past research focused on aggregated effects of scaffolds. What this paper adds Investigates how students learn with personalized scaffolds in terms of frequencies of learning activities and scaffold interaction. Takes a closer look at which learning activities and when the effects of personalized scaffolds occur. Examines how finer‐grained effects of personalized scaffolds correspond to learning outcomes. Implications for practice and/or policy Personalized scaffold effects vary across learning, and future research should consider finer‐grained investigations of SRL support in order to better understand their influence on learning. The number of personalized scaffolds provided should be reconsidered in the future as students only use some of the support provided, especially when task demands increase. Personalized scaffold interaction is linked to improvement in task performance, so future research should also focus on students' appropriate use of self‐regulated learning support.

Acute effects of (-)-gallocatechin gallate-rich green tea extract on the cerebral hemodynamic response of the prefrontal cortex in healthy humans.

The benefits of long-term consumption of green tea on the brain are well known. However, among many ingredients of green tea, the acute effects of (-)-gallocatechin gallate-rich green tea extract (GCG-GTE), have received comparatively less attention. Herein, we investigated the acute effects of oral ingestion of green tea with GCG-GTE, which contains close replicas of the ingredients of hot green tea, on task-dependent hemodynamics in the prefrontal cortex of healthy adult human brains. In this randomized, double-blind, placebo-controlled, parallel group trial, 35 healthy adults completed computerized cognitive tasks that demand activation of the prefrontal cortex at baseline and 1 h after consumption of placebo and 900 mg of GCG-GTE extract supplement. During cognitive testing, hemodynamic responses (change in HbO2 concentration) in the prefrontal cortex were assessed using functional near-infrared spectroscopy (fNIRS). In fNIRS data, significant group x session interactions were found in the left (p = 0.035) and right (p = 0.036) dorsolateral prefrontal cortex (DLPFC). In behavioral data, despite the numerical increase in the GCG-GTE group and the numerical decrease in the Placebo group, no significant differences were observed in the cognitive performance measure between the groups. The result suggests a single dose of orally administered GCG-GTE can reduce DLPFC activation in healthy humans even with increased task demand. GCG-GTE is a promising functional material that can affect neural efficiency to lower mental workload during cognitively demanding tasks. However, further studies are needed to verify this.

Multilingual Language Diversity Protects Native Language Production under Different Control Demands.

The use of multiple languages has been found to influence individuals' cognitive abilities. Although some studies have also investigated the effect of multilingualism on non-native language proficiency, fewer studies have focused on how multilingual experience affects native language production. This study investigated the effect of multilingualism on native language production, specifically examining control demands through a semantic Go/No-Go picture naming task. The multilingual experience was quantified using language entropy, which measures the uncertainty and diversity of language use. Control demands were achieved by manipulating the proportion of Go (i.e., naming) trials in different conditions. Results showed that as control demands increased, multilingual individuals exhibited poorer behavioral performance and greater brain activation throughout the brain. Moreover, more diverse language use was associated with higher accuracy in naming and more interconnected brain networks with greater involvement of domain-general neural resources and less domain-specific neural resources. Notably, the varied and balanced use of multiple languages enabled multilingual individuals to respond more efficiently to increased task demands during native language production.

What Is the Relationship between Metacognition and Mental Effort in Executive Functions? The Contribution of Neurophysiology.

Prolonged cognitive effort can be considered one of the core determinants of mental fatigue and may negatively affect the efficacy and efficiency of cognitive performance. Metacognition-understood as a multi-componential set of skills concerning awareness and control of one's own cognition-might reduce such negative outcomes. This study aimed to explore the relation between metacognitive skills, neurocognitive performance, and the level of mental effort as mirrored by electrophysiological (EEG) markers of cognitive load and task demand. A challenging cognitive task was used to prompt and collect metacognition reports, performance data (accuracy and response times-RTs), and physiological markers of mental effort (task-related changes of spectral power for standard EEG frequency bands) via wearable EEG. Data analysis highlighted that different aspects of metacognitive skills are associated with performance as measured by, respectively, accuracy and RTs. Furthermore, specific aspects of metacognitive skills were found to be consistently correlated with EEG markers of cognitive effort, regardless of increasing task demands. Finally, behavioral metrics mirroring the efficiency of information processing were found to be associated with different EEG markers of cognitive effort depending on the low or high demand imposed by the task.

56 Dunning-Kruger Effect and Anxiety in a Mexican population

Objective:The Dunning-Krueger effect is a cognitive bias where individuals tend to overestimate their abilities in areas where they are less competent. The Cordoba Naming Test (CNT) is a 30-item confrontation naming task. Hardy and Wright (2018) conditionally validated a measure of perceived mental workload called the NASA Task Load Index (NASA-TLX). Researchers reported that workload ratings on the NASA-TLX increased with increased task demands on a cognitive task. Anxiety is known as an emotion that can make an individual more susceptible to develop a mental health condition. We examine if the Dunning-Krueger effect occurs in a Mexican population with and without current symptoms of anxiety and possible factors driving individuals to overestimate their abilities on the CNT. We predicted the abnormal symptoms of anxiety (ASA) group would report better CNT performance, report higher perceived workloads on the CNT, and underperform on the CNT compared to the normal symptoms of anxiety (NSA) group. We also predicted the low-performance group would report better CNT performance, report higher perceived workloads on the CNT, and underperform on the CNT compared to the high-performance group.Participants and Methods:The sample consisted of 192 Mexican participants with NSA (79 low-performance &amp; 113 high-performance) and 74 Mexican participants with ASA (44 low-performance &amp; 30 high-performance). Participants completed the CNT, NASA-TLX, and the Hospital Anxiety and Depression Scale (HADS) in Spanish. The NASA-TLX was used to evaluate perceived workloads after the completion of the CNT. Meanwhile, the HADS was used to create our anxiety groups. Finally, CNT raw scores were converted into T-scores, which then were averaged to create the following two groups: low-performance (CNT T-Score &lt;50) and high-performance (CNT T-Score 50+). A series of 2x2 ANCOVAs, controlling for gender were used to evaluate CNT performance and perceived workloads.Results:We found a significant interaction where the low-performance ASA and the high-performance NSA groups demonstrated better CNT performance and reported higher perceived workloads (i.e., performance, temporal demand) on the CNT compared to their respective counterparts (i.e., low-performance NSA &amp; high-performance ASA groups), p's&lt;.05, ηp's2=.02. We found a main effect where the high-performance group outperformed the low-performance group on the CNT and reported lower perceived workloads on the CNT, p's&lt;.05, ηp's2 =.04-.46.Conclusions:The Dunning-Krueger effect did not occur in our sample. Participants that demonstrated better CNT performance also reported higher perceived workloads regardless of their current symptoms of anxiety. A possible explanation can be our sample's cultural norms of what would be considered as abnormal symptoms of anxiety, is a normal part of life, decreasing the possibilities to experience self-efficacy distoritions. Future studies should investigate whether the Dunning-Kruger effect may be influencing other aspects of cognitive functioning subjectively in Mexicans residing in Mexico and the United States with and without current symptoms of anxiety.

A - 15 Elucidating Patterns of Naturalistic Behavior in those with Self-Reported Functional Cognitive Decline.

There is relatively little known about the effect of subjective cognitive decline on everyday behaviors in community-dwelling older adults. We investigated use of compensatory strategies, busyness, and engagement in productive activities in older adults with subjective decline versus those without subjective decline. 353 adults (65+ years old) completed an online survey including demographic information, self-reported decline in functional cognition (Everyday Cognition Questionnaire; ECog), subjective busyness (Martin and Park Environmental Demands Questionnaire), engagement in productive activities (Temple Activities Engagement Questionnaire), and use of compensatory strategies (Memory Compensation Questionnaire). Two-tailed t-tests compared these variables amongst two groups: "decliners," (ECog Score > 1.49) and "non-decliners," (ND; ECog Score < 1.50). There were no significant differences in demographics between the decliners (mean age = 76.68, sd = 8.22, p = 3.00; mean edu = 15.55, sd = 3.97, p = 0.91) and ND (mean age = 75.71, sd = 6.93; mean edu = 15.50, sd = 3.19). Decliners reported greater use of compensatory strategies (mean = 95.58, sd = 20.21, p < 0.001) compared to ND (mean = 80.43, sd = 19.56). Decliners also reported greater daily busyness (mean = 14.47, sd = 5.7, p = 0.002) compared to ND (mean = 12.66, sd = 4.19), but no difference in the engagement in productive activities. Decliners utilize more compensatory strategies in their daily lives (e.g., using external aids, concentrating harder, etc.), and report feeling busier despite no difference in engagement of productive daily tasks. Future work should clarify how compensatory strategies in decliners are used and whether increased busyness reflects increased task demands or the use of compensatory strategies. Psychoeducation should promote compensatory strategies that are effective and alleviate subjective busyness.

Rollator usage lets young individuals switch movement strategies in sit-to-stand and stand-to-sit tasks

The transitions between sitting and standing have a high physical and coordination demand, frequently causing falls in older individuals. Rollators, or four-wheeled walkers, are often prescribed to reduce lower-limb load and to improve balance but have been found a fall risk. This study investigated how rollator support affects sit-to-stand and stand-to-sit movements. Twenty young participants stood up and sat down under three handle support conditions (unassisted, light touch, and full support). As increasing task demands may affect coordination, a challenging floor condition (balance pads) was included. Full-body kinematics and ground reaction forces were recorded, reduced in dimensionality by principal component analyses, and clustered by k-means into movement strategies. Rollator support caused the participants to switch strategies, especially when their balance was challenged, but did not lead to support-specific strategies, i.e., clusters that only comprise light touch or full support trials. Three strategies for sit-to-stand were found: forward leaning, hybrid, and vertical rise; two in the challenging condition (exaggerated forward and forward leaning). For stand-to-sit, three strategies were found: backward lowering, hybrid, and vertical lowering; two in the challenging condition (exaggerated forward and forward leaning). Hence, young individuals adjust their strategy selection to different conditions. Future studies may apply this methodology to older individuals to recommend safe strategies and ultimately reduce falls.

Cross-hemispheric recruitment during action planning with increasing task demand

The recruitment of cross-hemispheric counterparts of lateralized prefrontal brain regions with increasing processing demand is thought to increase memory performance despite cognitive aging, but was recently reported to be present also in young adults working at their capacity limit. Here we ask if cross-hemispheric recruitment is a general strategy of the adult brain in that executive task demand would modulate bilateral activation beyond prefrontal cortex and across cognitive tasks. We analyzed data sets from two fMRI experiments investigating retrospective working memory maintenance and prospective action planning. We confirmed a cross-hemispheric recruitment of prefrontal cortex across tasks and experiments. Changes in lateralization due to planning further surfaced in the cerebellum, dorsal premotor and posterior parietal cortex. Parietal cortex thereby exhibited cross-hemispheric recruitment also during spatial but not verbal working memory maintenance. Our results confirm a domain-general role of prefrontal cortex in cross-hemispheric recruitment. They further suggest that other task-specific brain regions also recruit their idling cross-hemispheric counterparts to relocate executive processing power.

Stress Coping Strategies among Teachers at Madrasah Ibtidaiyah Al-Qomar Nganjuk during the Covid-19 Pandemic

Background: COVID-19 pandemic has become a new source of stress among teachers. Education was originally carried out directly and has now changed to network-based (online), so it is not uncommon for teachers to experience work stress. Objective: This study aims to analyze stress coping among teachers at MI Al-Qomar Nganjuk during the COVID-19 pandemic. Methods: This study used qualitative research with a case study. There were 9 informants consisting of 1 key informant, 5 main informants, and 3 additional informants. Data collection techniques are in-depth interviews, observation, and documentation. Data analysis used thematic content analysis. The credibility test used triangulation of techniques and sources. Results: The results of the study state that the source of stress among teachers who come from stressors is task demands during the pandemic such as teachers being required to create learning innovations, achievement of student learning outcomes that have not been running optimally and increasing task demands. There are two stress coping used by the informants, problem-focused coping and emotional-focused coping. As many as 4 informants mostly use problem-focused coping with aspects of planful-focused coping and seeking social support. In addition, all key informants also use emotional-focused coping, which mostly uses positive reappraisal aspects. Conclusion: The informants are positive, as indicated by the condition of the informants after using the two copings, they feel better and have a positive impact on the stress they experience.

Boring But Demanding: Using Secondary Tasks to Counter the Driver Vigilance Decrement for Partially Automated Driving.

We investigated secondary-task-based countermeasures to the vigilance decrement during a simulated partially automated driving (PAD) task, with the goal of understanding the underlying mechanism of the vigilance decrement and maintaining driver vigilance in PAD. Partial driving automation requires a human driver to monitor the roadway, but humans are notoriously bad at monitoring tasks over long periods of time, demonstrating the vigilance decrement in such tasks. The overload explanations of the vigilance decrement predict the decrement to be worse with added secondary tasks due to increased task demands and depleted attentional resources, whereas the underload explanations predict the vigilance decrement to be alleviated with secondary tasks due to increased task engagement. Participants watched a driving video simulating PAD and were required to identify hazardous vehicles throughout the 45-min drive. A total of 117 participants were assigned to three different vigilance-intervention conditions including a driving-related secondary task (DR) condition, a non-driving-related secondary task (NDR) condition, and a control condition with no secondary tasks. Overall, the vigilance decrement was shown over time, reflected in increased response times, reduced hazard detection rates, reduced response sensitivity, shifted response criterion, and subjective reports on task-induced stress. Compared to the DR and the control conditions, the NDR displayed a mitigated vigilance decrement. This study provided convergent evidence for both resource depletion and disengagement as sources of the vigilance decrement. The practical implication is that infrequent and intermittent breaks using a non-driving related task may help alleviate the vigilance decrement in PAD systems.

Alpha Oscillations During Effortful Continuous Speech: From Scalp EEG to Ear-EEG.

The purpose of this study was to investigate alpha power as an objective measure of effortful listening in continuous speech with scalp and ear-EEG. Scalp and ear-EEG were recorded simultaneously during presentation of a 33-s news clip in the presence of 16-talker babble noise. Four different signal-to-noise ratios (SNRs) were used to manipulate task demand. The effects of changes in SNR were investigated on alpha event-related synchronization (ERS) and desynchronization (ERD). Alpha activity was extracted from scalp EEG using different referencing methods (common average and symmetrical bi-polar) in different regions of the brain (parietal and temporal) and ear-EEG. Alpha ERS decreased with decreasing SNR (i.e., increasing task demand) in both scalp and ear-EEG. Alpha ERS was also positively correlated to behavioural performance which was based on the questions regarding the contents of the speech. Alpha ERS/ERD is better suited to track performance of a continuous speech than listening effort. EEG alpha power in continuous speech may indicate of how well the speech was perceived and it can be measured with both scalp and Ear-EEG.

Vigilance decrement and mind-wandering in sustained attention tasks: Two sides of the same coin?

Decrements in performance and the propensity for increased mind-wandering (i.e., task-unrelated thoughts) across time-on-task are two pervasive phenomena observed when people perform vigilance tasks. In the present study, we asked whether processes that lead to vigilance decrement and processes that foster the propensity for mind-wandering (MW) can be dissociated or whether they share a common mechanism. In one experiment, we introduced two critical manipulations: increasing task demands and applying anodal high-definition transcranial direct current stimulation (HD-tDCS) to the left dorsolateral prefrontal cortex. Seventy-eight participants were randomly assigned to one of four groups resulting from the factorial combination of task demand (low, high) and stimulation (anodal, sham). Participants completed the sustained attention to response task (SART), which included thought probes on intentional and unintentional MW. In addition, we investigated the crucial role of alpha oscillations in a novel approach. By assessing pre-post resting EEG, we explored whether participants' variability in baseline alpha power predicted performance in MW and vigilance decrement related to tDCS or task demands, respectively, and whether such variability was a stable characteristic of participants. Our results showed a double dissociation, such that task demands exclusively affected vigilance decrement, while anodal tDCS exclusively affected the rate of MW. Furthermore, the slope of the vigilance decrement function and MW rate (overall, intentional and unintentional) did not correlate. Critically, resting state alpha-band activity predicted tDCS-related gains in unintentional MW alone, but not in vigilance decrement, and remained stable after participants completed the task. These results show that when a sustained attention task involving executive vigilance, such as the SART, is designed to elicit both vigilance decrement effects and MW, the processes leading to vigilance decrement should be differentiated from those responsible for MW, a claim that is supported by the double dissociation observed here and the lack of correlation between the measures chosen to assess both phenomena. Furthermore, the results provide the first evidence of how individual differences in alpha power at baseline may be of crucial importance in predicting the effects of tDCS on MW propensity.