Effect of mental fatigue caused by mobile 3D viewing on selective attention: an ERP study

Objective assessment of cognitive fatigue: a bibliometric analysis

Aim

The objective of this study was to gain insight into the nature of cognitive fatigue and to identify future trends of objective assessment techniques in this field.

Methods

One thousand and eighty-five articles were retrieved from the Web of Science Core Collection database. R version 4.3.1, VOSviewer 1.6.20, CiteSpace 6.2.R4, and Microsoft Excel 2019 were used to perform the analysis.

Results

A total of 704 institutes from 56 countries participated in the relevant research, while the People's Republic of China contributed 126 articles and was the leading country. The most productive institute was the University of Gothenburg. Johansson Birgitta from the University of Gothenburg has posted the most articles (n = 13). The PLOS ONE published most papers (n = 38). The Neurosciences covered the most citations (n = 1,094). A total of 3,116 keywords were extracted and those with high frequency were mental fatigue, performance, quality-of-life, etc. Keywords mapping analysis indicated that cognitive fatigue caused by continuous work and traumatic brain injury, as well as its rehabilitation, have become the current research trend. The most co-cited literature was published in Sports Medicine. The strongest citation burst was related to electroencephalogram (EEG) event-related potential and spectral power analysis.

Conclusion

Publication information of related literature on the objective assessment of cognitive fatigue from 2007 to 2024 was summarized, including country and institute of origin, authors, and published journal, offering the current hotspots and novel directions in this field.

Effects of Temporary Respiration Exercise with Individual Harmonic Frequency on Blood Pressure and Autonomic Balance

This study investigated the effects of modulated respiration on blood pressure and autonomic balance to develop a healthcare application system for stabilizing autonomic balance. Thirty-two participants were asked to perform self-regulated tasks with 18 different respiration sequences, and their electrocardiograms (ECG) and blood pressure were measured. Changes in cardiovascular system functions and blood pressure were compared between free-breathing and various respiration conditions. Systolic and diastolic blood pressures stabilized after individual harmonic breathing. Autonomic balance, characterized by heart rate variability, was also stabilized with brief respiration training according to harmonic frequency. Five machine-learning algorithms were used to classify the two opposing factors between the free and modulated breathing conditions. The random forest models outperformed the other classifiers in the training data of systolic blood pressure and heart rate variability. The mean areas under the curves (AUCs) were 0.82 for systolic blood pressure and 0.98 for heart rate variability. Our findings lend support that blood pressure and autonomic balance were improved by temporary harmonic frequency respiration. This study provides a self-regulated respiration system that can control and help stabilize blood pressure and autonomic balance, which would help reduce mental stress and enhance human task performance in various fields.

ERP Study of Mine Management System Warning Interface under Fatigue

Due to the large volume of monitoring data in mines, concentrating on and reviewing the data for a long period of time will easily cause fatigue. To study the influence of different visual codes of early-warning interfaces on the response of individuals who are fatigued, the changes in the subjective fatigue and corresponding frequency waves are compared before and after a fatigue-inducing task, as well as using event-related potential to study the behavioral data and EEG signals of subjects who participated in an oddball task on an early-warning interface. The results showed that all 14 subjects became fatigued after the fatigue-inducing task, and the amplitude of P200 when text is used in a fatigued state was the largest, with the longest latency. The subjects showed a slower reaction time and a reduced accuracy rate, thus indicating that in designing a warning interface, when text rather than color is used as a visual code, the operating load will be larger, mental load is increased, and attention resources are consumed. The experimental results provide the basis for the design and evaluation of early-warning interfaces of mine management systems.

Listening to 15 Hz Binaural Beats Enhances the Connectivity of Functional Brain Networks in the Mental Fatigue State—An EEG Study

Introduction: It is clear that mental fatigue can have many negative impacts on individuals, such as impairing cognitive function or affecting performance. The aim of this study was to investigate the role of sound interventions in combating mental fatigue. Method: The subjects were assessed on various scales, a psychomotor vigilance task (PVT) task, and a 3 min resting-state electroencephalogram (EEG), followed by a 20 min mental fatigue–inducing task (Time Load Dual Back, TloadDback), during which subjects in different condition groups listened to either 15 Hz binaural beats, 40 Hz binaural beats, relaxing music, or a 240 Hz pure tone. After the mental fatigue–inducing task, subjects were again assessed on various scales, a PVT task, and a 3 min resting-state EEG. Results: After the fatigue-inducing task, there was no significant difference between the four groups on the scales or the PVT task performance. In TloadDback, the accuracy rate of the 40 Hz binaural beats group and the relaxing music group decreased in the middle stage of the task, while the 15 Hz binaural beats group and the 240 Hz pure tone group remained unchanged in all stages of the task. The EEG results showed that after fatigue inducement, the average path length of the 15 Hz binaural beats group decreased, and local efficiency showed an increasing tendency, indicating enhanced brain network connectivity. Meanwhile, the 240 Hz pure tone group showed enhanced functional connectivity, suggesting a state of mental fatigue in the group. Conclusions: The results of this study show that listening to 15 Hz binaural beats is a proven intervention for mental fatigue that can contribute to maintaining working memory function, enhancing brain topological structure, and alleviating the decline in brain function that occurs in a mentally fatigued state. As such, these results are of great scientific and practical value.

Mental Fatigue Impairs Postural Stability in Older Adults

Purpose: Postural instability can increase the risk of a fall in older adults. In this study, the impact of mental fatigue on postural stability among healthy older adults was investigated. Method: Participants were randomly divided into two groups: experimental and control groups. Postural stability of all participants was tested using the Biodex Balance System (BBS) before and immediately after watching a 30-min documentary program (control group) or completing a 30-min Stroop task (experimental group). Subjective ratings of mental fatigue were measured before and after the Stroop task or watching documentary program. Results: The results indicated that experimental group revealed higher stability scores in the posttest compared to pretest (P ≤ 0.001). However, there were no significant differences for BBS scores between pre and posttest in control group (P = .688). In addition, posttest of subjective ratings of mental fatigue was significantly different between experimental and control groups. Finally, there was also evidence of an association between Visual analog scale and BBS scores in the experimental group (rs = 0.712, P = .002). Conclusions: Mental fatigue caused by Stroop task had a negative impact on postural stability in older adults. This may be due to reduction in attentional resources that was caused by mental fatigue. Thus, mental fatigue could be considered as a risk factor for increased risk of falls in older adults.

Anti-Heartbeat-Evoked Potentials Performance in Event-Related Potentials-Based Mental Workload Assessment

The aim of this study was to determine the effect of heartbeat-evoked potentials (HEPs) on the performance of an event-related potential (ERP)-based classification of mental workload (MWL). We produced low- and high-MWLs using a mental arithmetic task and measured the ERP response of 14 participants. ERP trials were divided into three conditions based on the effect of HEPs on ERPs: ERP_HEP, containing the heartbeat in a period of 280–700ms in ERP epochs after the target; ERP_A-HEP, not including the heartbeat within the same period; and ERP_T, all trials including ERP_A-HEP and ERP_HEP. We then compared MWL classification performance using the amplitude and latency of the P600 ERP among the three conditions. The ERP_A-HEP condition achieved an accuracy of 100% using a radial basis function-support vector machine (with 10-fold cross-validation), showing an increase of 14.3 and 28.6% in accuracy compared to ERP_T (85.7%) and ERP_HEP (71.4%), respectively. The results suggest that evoked potentials caused by heartbeat overlapped or interfered with the ERPs and weakened the ERP response to stimuli. This study reveals the effect of the evoked potentials induced by heartbeats on the performance of the MWL classification based on ERPs.

Non-Contact Measurement of Motion Sickness Using Pupillary Rhythms from an Infrared Camera

Both physiological and neurological mechanisms are reflected in pupillary rhythms via neural pathways between the brain and pupil nerves. This study aims to interpret the phenomenon of motion sickness such as fatigue, anxiety, nausea and disorientation using these mechanisms and to develop an advanced non-contact measurement method from an infrared webcam. Twenty-four volunteers (12 females) experienced virtual reality content through both two-dimensional and head-mounted device interpretations. An irregular pattern of the pupillary rhythms, demonstrated by an increasing mean and standard deviation of pupil diameter and decreasing pupillary rhythm coherence ratio, was revealed after the participants experienced motion sickness. The motion sickness was induced while watching the head-mounted device as compared to the two-dimensional virtual reality, with the motion sickness strongly related to the visual information processing load. In addition, the proposed method was verified using a new experimental dataset for 23 participants (11 females), with a classification performance of 89.6% (n = 48) and 80.4% (n = 46) for training and test sets using a support vector machine with a radial basis function kernel, respectively. The proposed method was proven to be capable of quantitatively measuring and monitoring motion sickness in real-time in a simple, economical and contactless manner using an infrared camera.

Investigate the 3D Visual Fatigue Using Modified Depth-Related Visual Evoked Potential Paradigm

Prolonged viewing of 3D content may result in severe fatigue symptoms, giving negative user experience thus hindering the development of 3D industry. For 3D visual fatigue evaluation, previous studies focused on exploring the changes of frequency-domain features in EEG for various fatigue degrees. However, their time-domain features were scarcely investigated. In this study, a modified paradigm with a random disparities order is adopted to evoke the depth-related visual evoked potentials (DVEPs). Then the characteristics of the DVEPs components for various fatigue degrees are compared using one-way repeated-measurement ANOVA. Point-by-point permutation statistics revealed sample points from 100ms to 170ms - including P1 and N1 - in sensors Pz and P4 changed significantly with visual fatigue. More specifically, we find that the amplitudes of P1 and N1 change significantly when visual fatigue increases. Additionally, independent component analysis identify P1 and N1 which originate from posterior cingulate cortex are associated statistically with 3D visual fatigue. Our results indicate there is a significant correlation between 3D visual fatigue and P1 amplitude, as well as N1, of DVEPs on right parietal areas. We believe the characteristics (e.g., amplitude and latency) of identified components may be the indicators of 3D visual fatigue evaluation. Furthermore, we argue that 3D visual fatigue may be associated with the activities decrease of the attention and the processing capacity of disparity.

Analysis of the Relationship between the Expression Levels of Neutrophil Gelatinase-Associated Lipocalin and Cytokine Genes in Bone Marrow

Background: Recently, various associations of NGAL with several hematological cancers have been reported. However, given that the regulation of NGAL gene expression by cytokines is tissue-specific, NGAL expression in relation to those of cytokine genes has not been analyzed in bone marrow (BM) tissue. The purpose of this study was to analyze the association between NGAL and 48 cytokine gene expression levels in mononuclear cells (MNCs) of BM at the time of diagnosis of hematological malignancy and to explore the expression pattern of NGAL and related cytokine genes in patients with hematological malignancies and controls. Methods: BM MNCs were isolated from 48 patients, who were classified as patients presenting myeloproliferative neoplasm, acute myeloid leukemia, myelodysplastic syndrome, and as controls. NGAL and cytokine genes were analyzed using NanoString. Data on hematological parameters were collected from medical records. Single and multiple regression analyses were performed to analyze relationships. Results: Normalized counts of 26 cytokine genes were related to NGAL normalized counts, while STAT3 and TLR4 normalized counts had the highest explanatory power. The following multiple regression model was developed: NGAL normalized counts=4316.825 + 9.056 × STAT3 normalized counts + 844.226 × IL5 normalized counts + 17.540 × TLR1 normalized counts - 28.206 × TLR2 normalized counts - 42.524 × IRAK4 normalized counts. In the multiple regression analysis, STAT3 and TLR4 normalized counts showed multicollinearity. NGAL, STAT3, IL5, and TLR4 normalized counts showed similar intergroup patterns. Conclusions: NGAL normalized counts was predicted by a multiple regression model, while they showed similar intergroup patterns to STAT3, IL5, and TLR4 normalized counts.

Study of mental workload imposed by different tasks based on teleoperation

To explore mental workload and methods for dynamically monitoring mental workload imposed by complex tasks, this study constructed a virtual operating environment according to three cognitive steps: perception, judgment-making and action execution. Dynamic characteristics of mental workload were then analyzed employing subjective questionnaires, performance data and electroencephalography (EEG) characteristics. The analysis of non-linear dynamic characteristics of EEG signals showed that the fractal box dimension features of EEG signals are quite sensitive to the level of mental workload, exercising a significant impact on the four brain areas. The sample entropy is also quite sensitive to the level of mental workload, exercising a significant impact on the frontal, central and occipital areas. Based on this study, operational tasks can be dynamically assigned according to the state of personnel load and the safety and efficiency of the operation of the human-machine system can be ensured.

Research on the Quantitative Method of Cognitive Loading in a Virtual Reality System

Aimed at the problem of how to objectively obtain the threshold of a user’s cognitive load in a virtual reality interactive system, a method for user cognitive load quantification based on an eye movement experiment is proposed. Eye movement data were collected in the virtual reality interaction process by using an eye movement instrument. Taking the number of fixation points, the average fixation duration, the average saccade length, and the number of the first mouse clicking fixation points as the independent variables, and the number of backward-looking times and the value of user cognitive load as the dependent variables, a cognitive load evaluation model was established based on the probabilistic neural network. The model was validated by using eye movement data and subjective cognitive load data. The results show that the absolute error and relative mean square error were 6.52%–16.01% and 6.64%–23.21%, respectively. Therefore, the model is feasible.

IR-camera-based measurements of 2D/3D cognitive fatigue in 2D/3D display system using task-evoked pupillary response

This study was carried out to evaluate a method used to measure three-dimensional (3D) cognitive fatigue based on the pupillary response. This technique was designed to overcome measurement burdens by using non-contact methods. The pupillary response is related to cognitive function by a neural pathway and may be an indicator of 3D cognitive fatigue. Twenty-six undergraduate students (including 14 women) watched both 2D and 3D versions of a video for 70 min. The participants experienced visual fatigue after viewing the 3D content. Measures such as subjective rating, response time, event-related potential latency, heartbeat-evoked potential (HEP) alpha power, and task-evoked pupillary response (TEPR) latency were significantly different. Multitrait-multimethod matrix analysis indicated that HEP and TEPR latency measures had stronger reliability and higher correlations with 3D cognitive fatigue than other measures. TEPR latency may be useful for quantitatively determining 3D visual fatigue, as it can be easily used to evaluate 3D visual fatigue using a non-contact method without measuring burden.

Study on the Preferred Application-Oriented Index for Mental Fatigue Detection

Most of the research on mental fatigue evaluation has mainly concentrated on some indexes that require sophisticated and large instruments that make the detection of mental fatigue cumbersome, time-consuming, and difficult to apply on a large scale. A quick and sensitive mental fatigue detection index is necessary so that mentally fatigued workers can be alerted in time and take corresponding countermeasures. However, to date, no studies have compared the sensitivity of common objective evaluation indexes. To solve these problems, this study recruited 56 human subjects. These subjects were evaluated using six fatigue indexes: the Stanford sleepiness scale, digital span, digital decoding, short-term memory, critical flicker fusion frequency (CFF), and speed perception deviation. The results of the fatigue tests before and after mental fatigue were compared, and a one-way analysis of variance (ANOVA) was performed on the speed perception deviation. The results indicated the significance of this index. Considering individual differences, the relative fatigue index (RFI) was proposed to compare the sensitivity of the indexes. The results showed that when the self-rated fatigue grade changed from non-fatigue to mild fatigue, the ranges of RFI values for digital span, digital decoding, short-term memory, and CFF were 0.175–0.258, 0.194–0.316, 0.068–0.139, and 0.055–0.075, respectively. Correspondingly, when the self-rated fatigue grade changed to severe fatigue, the ranges of RFI values for the above indexes were 0.415–0.577, 0.482–0.669, 0.329–0.396, and 0.114–0.218, respectively. These results suggest that the sensitivity of the digital decoding, digital span, short-term memory, and CFF decreased sequentially when the self-evaluated fatigue grade changed from no fatigue to mild or severe fatigue. The RFI individuality of the speed perception deviation is highly variable and is not suitable as an evaluation index. In mental fatigue testing, digital decoding testing can provide faster, more convenient, and more accurate results.

Cognitive responses and cortical oscillatory processing at various stereoscopic depths - a simultaneous EEG/MEG study

Due to the recent explosion in various forms of 3D content, the evaluation of such content from a neuroscience perspective is quite interesting. However, existing investigations of cortical oscillatory responses in stereoscopic depth perception are quite rare. Therefore, we investigated spatiotemporal and spatio-temporo-spectral features at four different stereoscopic depths within the comfort zone. We adopted a simultaneous EEG/MEG acquisition technique to collect the oscillatory responses of eight participants. We defined subject-specific retinal disparities and designed a single trial-based stereoscopic viewing experimental paradigm. In the group analysis, we observed that, as the depth increased from Level 1 to Level 3, there was a time-locked increase in the N200 component in MEG and the P300 component in EEG in the occipital and parietal areas, respectively. In addition, initial alpha and beta event-related desynchronizations (ERD) were observed at approximately 500 to 1000 msec, while theta, alpha, and beta event-related synchronizations (ERS) appeared at approximately 1000 to 2000 ms. Interestingly, there was a saturation point in the increase in cognitive responses, including N200, P300, and alpha ERD, even when the depth increased only within the comfort zone. Meanwhile, the magnitude of low beta ERD decreased in the dorsal pathway as depth increased. From these findings, we concluded that cognitive responses are likely to become saturated in the visual comfort zone, while perceptual load may increase with depth.

Effects of mental workload on involuntary attention: A somatosensory ERP study

Previous psychophysiological assessments of mental workload have relied on the addition of visual or auditory stimuli. This study investigated the tactile ERP and EEG spectral power correlates of mental workload by relating limited-capacity involuntary attention allocation to changes in late positive potential (LPP) amplitude, alpha, and theta powers. We examined whether mental workload (high-level cognitive control) can be evaluated using somatosensory stimuli. Sixteen participants all performed three tasks of varying difficulty. Two dual n-back tasks (n = 1 and 2) were used to investigate the degree to which mental workload affected the LPP amplitudes and EEG spectral powers evoked by ignoring salient tactile stimuli. In control trials, tactile vibrations were applied at random without dual n-back tasks. Subjective mental workload of each task was rated using the NASA Task Load Index. LPP amplitudes at Pz were significantly smaller in the dual-2-back trials compared to control and dual-1-back trials. Significantly increased theta power at Fz and reduced alpha power at Pz were found in the dual-2-back condition compared to control and dual-1-back condition. There was no significant difference between control and dual-1-back trials. The same pattern was found for subjective ratings of cognitive workload. These results indicate that the dual-2-back task imposed a significantly greater mental workload, causing impaired cognitive-control functions. Our findings support the notion that selective attention mechanisms necessary for effectively allocating and modulating attentional resources are temporarily impaired during the mentally overloaded state.

Evaluation of passive polarized stereoscopic 3D display for visual & mental fatigues

Visual and mental fatigues induced by active shutter stereoscopic 3D (S3D) display have been reported using event-related brain potentials (ERP). An important question, that is whether such effects (visual & mental fatigues) can be found in passive polarized S3D display, is answered here. Sixty-eight healthy participants are divided into 2D and S3D groups and subjected to an oddball paradigm after being exposed to S3D videos with passive polarized display or 2D display. The age and fluid intelligence ability of the participants are controlled between the groups. ERP results do not show any significant differences between S3D and 2D groups to find the aftereffects of S3D in terms of visual and mental fatigues. Hence, we conclude that passive polarized S3D display technology may not induce visual and/or mental fatigue which may increase the cognitive load and suppress the ERP components.