EEG-based mental fatigue detection by spectral non-negative matrix factorization.

Introduction: Fatigue is a gradual and cumulative process. This mindset is related to the lack of motivation to make any effort, as well as decreased efficiency, attentiveness, and, eventually, malfunction. Aim: The present study aims to investigate how mental and muscle fatigue affects spatial working memory. Method: The research method was quasi-experimental and was performed using the pretestposttest design. The participants in this study were 20 to 30 year old male students of Shahid Beheshti University of Tehran in 2021, of whom, 14 subjects were selected by convincing method as the sample using the G-Power approach and previous investigations. The Mental Fatigue Self-Assessment Scale, Corsi Block software, Stroop software, and the Monark Bike Ergometer were utilized. In addition, the repeated measurement analysis of variance test in SPSS-23 was used to analyze the data. Results: The results indicated that mental fatigue condition had a significant effect on working memory (P=0.002); and has reduced the efficiency of working memory. But muscle fatigue conditions had no significant effect on assessing working memory, and in these conditions there was a better performance in working memory (P=0.065). Conclusion: The findings of this study emphasize the importance of mental fatigue in reducing working memory performance, even though this type of fatigue is related to cognitive and cerebral functioning. Accordingly, the findings are in line with a top-down approach, as well as cognitive perspectives such as generalized motor program theory.

Purpose. The purpose of the article is the formation of theoretical, methodological and practical foundations for the implementation of marketing tools to assess the impact of consumer fatigue from making everyday decisions on brand loyalty and purchasing behaviour in stores. Methodology of research. The theoretical and methodological basis of the article was formed by the provisions of behavioural economics, neuro-marketing, and branding. The study is based on the dialectical method of learning the influence of consumer fatigue from decision-making on brand loyalty. General scientific and special methods are used within the limits of the mentioned approach, in particular: comparison – to determine the advantages and disadvantages of different groups of marketing tools; questionnaire survey – for a pilot study of the criteria for making a decision on the purchase of goods by consumers in stores; mathematical modelling – for evaluating the data obtained during the experiment and determining the tendencies of choosing the company's product or brand by consumers during fatigue; analysis and synthesis – to form a mechanism for the implementation of neuro-marketing tools by companies; induction and deduction – to interpret conclusions based on research results. Findings. The phenomenon of consumer decision fatigue resulting from repeated choice-making is explored, leading to mental exhaustion and impaired behaviour control, affecting brand loyalty. A concept is formulated for the application of neuro-marketing tools to understand consumer behaviour in retail stores, which engages all human sensory organs, including audio influence, visualization, tactile stimulation, scent influence, and taste stimulation. Pilot study of the purchasing behaviour of consumers in a state of physical or mental fatigue and without it was conducted. It has been established that closer to the evening, consumer fatigue from decision-making is observed, as during the day people may be under the influence of stressful factors, depleting emotional and cognitive resources. The factors that are important in making a decision regarding the choice of a product of a certain brand are singled out. The hypothesis regarding the influence of consumer fatigue from decision-making on the formation of brand loyalty was confirmed. Originality. The concept is formulated of using neuromarketing tools for a better understanding of consumer behavior in stores, a more detailed analysis of the decision-making process and their purchasing behavior, the formation of habits and loyalty to company brands, consumer reactions to product packaging and labeling in a state of fatigue. Practical value. The results of the pilot study will help create more effective marketing campaigns using a personalized approach to consumers and simplified communication. Key words: consumer behaviour, decision fatigue, marketing, shopping in stores, brand loyalty, neuro-marketing.

The objective was to study changes in EEG time-domain Kolmogorov complexity under different mental fatigue state and to evaluate mental fatigue using Lempel-Ziv complexity analysis of spontaneous EEG in healthy human subjects. EEG data for healthy subjects were acquired using a net of 2 electrodes (Fp1 and Fp2) at PM 4:00, AM 12:00 and AM 3:00 in the 24 hours sleep-deprived mental fatigue experiments. It was presented that initial results for eight subjects examined in three different mental fa-tigue state with 2-channel EEG time-domain Lempel-Ziv complexity computations. It was found that the value of mean Lempel-Ziv com-plexity corresponding to a special mental state fluctuates within the special range and the value of C(n) increases with mental fatigue increasing for the total frequency spectrum. The result in-dicates that the value of C(n) is strongly cor-relative with the mental fatigue state. These re-sults suggest that it may be possible to nonin-vasively differentiate different mental fatigue level according to the value of C(n) for particular mental state from scalp spontaneous EEG data. This method may be useful in further research and efforts to evaluate mental fatigue level ob-jectively. It may also provide a basis for the study of effects of mental fatigue on central neural system.

Mental fatigue is one kind of exhaustion that occurs in a person's mental state. Mental fatigue will arise if the brain is continuously forced to work. This mental fatigue is also common to happen to the senior high school student, especially in Indonesia because mostly they attend the school as a full day school. This study is exploring the mental fatigue condition in 13 senior high school students who attend a full day school by using EEG by selecting the appropriate feature for recognizing the mental fatigue. Recently, EEG technology has been implemented by some studies in the past to explore mental fatigue. In this study, EEG recording is held in the morning and carried out without stimulation. Meanwhile second measurement is used as a test condition. In the second test, the EEG recording was held in the afternoon, and stimulation of the arithmetic test was given to induce the fatigue. Baseline conditions describe the condition of fresh, while the second test conditions describe the condition of fatigue. The feature extraction process was done in time domain by analyzing 4 features: mean, mean absolute, standard deviation, and the number of zero crossing. Pearson correlation was applied to select the features by ranking the correlation between baseline conditions and test conditions $(\mathbf{R-value}=1)$ . Using those data, F-Test calculation is done on each band (Alpha, Beta, Tetha) to verify fatigue condition. Based on P-Value from F-Test calculation, we conclude Beta and Theta band showed a significant increase during fatigue condition $(\mathbf{P-Value} compared to alpha band.

To investigate the effects of mental fatigue on soccer-specific physical and technical performance. This investigation consisted of two separate studies. Study 1 assessed the soccer-specific physical performance of 12 moderately trained soccer players using the Yo-Yo Intermittent Recovery Test, Level 1 (Yo-Yo IR1). Study 2 assessed the soccer-specific technical performance of 14 experienced soccer players using the Loughborough Soccer Passing and Shooting Tests (LSPT, LSST). Each test was performed on two occasions and preceded, in a randomized, counterbalanced order, by 30 min of the Stroop task (mentally fatiguing treatment) or 30 min of reading magazines (control treatment). Subjective ratings of mental fatigue were measured before and after treatment, and mental effort and motivation were measured after treatment. Distance run, heart rate, and ratings of perceived exertion were recorded during the Yo-Yo IR1. LSPT performance time was calculated as original time plus penalty time. LSST performance was assessed using shot speed, shot accuracy, and shot sequence time. Subjective ratings of mental fatigue and effort were higher after the Stroop task in both studies (P < 0.001), whereas motivation was similar between conditions. This mental fatigue significantly reduced running distance in the Yo-Yo IR1 (P < 0.001). No difference in heart rate existed between conditions, whereas ratings of perceived exertion were significantly higher at iso-time in the mental fatigue condition (P < 0.01). LSPT original time and performance time were not different between conditions; however, penalty time significantly increased in the mental fatigue condition (P = 0.015). Mental fatigue also impaired shot speed (P = 0.024) and accuracy (P < 0.01), whereas shot sequence time was similar between conditions. Mental fatigue impairs soccer-specific running, passing, and shooting performance.

This study investigated the impact of mental fatigue and self-controlled versus yoked feedback on learning a force production task. We randomly assigned 44 non-athlete male students (Mage = 21.4, SD = 1.4 years) to four groups; (a) MF&SCF = mental fatigue & self-controlled feedback, (b) MF&Y = mental fatigue & yoked, (c) NMF&SCF = no mental fatigue & self-controlled feedback, and (d) NMF&Y = no mental fatigue & yoked). SCF group participants were provided feedback whenever they requested it, while YK group participants received feedback according to a schedule created by their SCF counterparts. To induce mental fatigue, participants performed a Stroop color-word task for one hour. During the acquisition (practice) phase, participants were asked to produce a given percentage of their maximum force (20%) in 12 blocks of six trials. We recorded the participants' absolute error at the end of the acquisition phase, the immediate retention test, the first transfer test, and the second transfer test (after 24 hours and without any further mental fatigue). The acquisition phase data were analyzed in a 2 (feedback) × 2 (mental fatigue) × 12 (block) ANOVA with repeated measures on the last factor, while the retention and transfer data were analyzed in 2 (feedback) × 2 (mental fatigue) ANOVAs. We found that all four groups made significant progress during practice (p < .001), but there were no significant group differences during this phase (p>.05). There was a significant interaction effect of self-controlled feedback and mental fatigue at retention (p = .018) and transfer testing (p < .001). In the mental fatigue condition, participants in the self-controlled group had poorer learning compared to participants in the yoked group; but when not mentally fatigued, participants in the self-controlled group had better learning than those in the yoked group. These findings suggest that mental fatigue reduces typical advantages of self-controlled feedback in motor learning.

<h3>Background</h3> A lot of controversy exists about how fatigue affects injury risk. Within the fatigue spectrum, mental fatigue impairs visuomotor skills, reaction time and decision-making. Recently, adaptability has been put forward as an important driver in understanding injury occurrence and injury prevention. It is hypothesised that mental fatigue decreases an athlete’s adaptability by means of an increased visuomotor reaction time and diminished ability for decision-making and visuomotor skill execution. <h3>Objective</h3> To assess the impact of mental fatigue on functional tests used in injury risk profiling and if mental fatigue decreases an athlete adaptability. <h3>Design</h3> Randomized counterbalanced cross-over design. <h3>Setting</h3> Primary prevention. <h3>Participants</h3> Fourteen healthy participants (age = 22 ± 1 years; height = 176.9 ± 8.4 cm; weight = 69.7 ± 10.4 kg). <h3>Interventions</h3> Mental fatigue was induced by a 90-minute 100% incongruent Stroop color word test, while the control task included watching a 90-minute documentary. <h3>Main Outcome Measurements</h3> Y-balance test (YBT), Reactive balance test (RBT), Single leg hop test (SLH) and countermovement jump (CMJ) performance was evaluated pre-post mental fatigue. Mental fatigue was evaluated using the M-VAS, Stroop and Eriksen-Flanker task performance outcomes. <h3>Results</h3> Mental fatigue was successfully induced at the subjective level with a significant increase in M-VAS (p&lt;0.001), with no decrease in performance on the Stroop and Eriksen-Flanker task. Mental fatigue did not affect YBT, SLH and the CMJ performance. However, RBT accuracy significantly decreased in mental fatigue condition (p=0.024), while the visuomotor reaction time of the RBT remained unaffected. <h3>Conclusions</h3> This is the first experiment to illustrate that mental fatigue affects functional adaptability, as accuracy in response to environmental stimuli decreases. However, traditional functional test perfmance remains unaffected. Therefore, both neurocognitive functional tests and mental fatigue responses should be considered within injury risk profiling strategies. Prospective study designs within the injury prevention domain should include neurocognitive functional tests to investigate the possible relationship of these tests with sports injuries.

To test the effects of mental fatigue (MF) on tackling technique on the dominant and nondominant shoulders in rugby union. Twenty male amateur rugby union players and a total of 953 tackles were analyzed. A randomized crossover counterbalanced design was used across a non-MF (control) and an MF condition. During each condition, each player performed 24 tackles, divided into 4 sets of 6 tackles (3 tackles on each shoulder). In the MF condition, players performed the Stroop Task between each set of tackles. A video recording of each tackle was used to evaluate each player's technical proficiency. A score of 1 point was awarded if a specific technique was performed correctly, and 0 point was given if not. The total score, measured in arbitrary units (AU) out of 11, represents the player's overall tackling proficiency. Overall, players displayed a significantly lower technical proficiency score in the MF condition compared to control (set 2: control 7.30 [7.04-7.57] AU vs MF 6.91 [6.70-7.12] AU, P = .009, effect size (ES) = 0.30 small and set 3: control 7.34 [7.11-7.57] AU vs MF 6.88 [6.66-7.11] AU, P = .002, ES = 0.37 small). For the nondominant shoulder, players had a significantly lower technical proficiency score during the MF condition at set 2 (control 7.05 [6.68-7.41] AU vs MF 6.69 [6.42-6.96] AU, P = .047, ES = 0.29 small) and set 3 (control 7.14 [6.83-7.45] AU vs MF 6.61 [6.35-6.87] AU, P = .007, ES = 0.49 small). MF can diminish a player's overall tackling proficiency, especially when tackling on the nondominant shoulder. The physiological mechanism for this finding may be impaired executive function and suboptimal functioning of neural signals and pathways, which result in less skillful coordination of movement. To further understand and explain MF-induced physiological changes in tackling, the feasibility of monitoring brain activity (such as electroencephalogram) and neuromuscular function (such as electromyogram) needs to be investigated. The findings from this study may also contribute to the development of more effective tackle training programs for injury prevention and performance.

Peers are thought to increase adolescents' risk-taking behavior, at least in part, by heightening their sensitivity to rewards. In this study, we investigate whether the effect of peers on late adolescent males is exacerbated when youth are cognitively fatigued, a state characterized by weakened cognitive control and heightened orientation toward rewards, and well established as a factor that compromises decision making. We hypothesized that fatigued adolescents' top-down regulation of reward-related impulses may be compromised, thereby potentially amplifying the effect of peers on reward- and risk-seeking behavior. Late adolescent males between 18 and 22 years old (mean age = 19.64, SD = 1.22; 61% Caucasian) completed a decision-making battery either alone or in the presence of 3 same-sex peers, and were either cognitively fatigued or non-fatigued. We compared behavior between four experimental groups-fatigued adolescents in a peer group, non-fatigued adolescents in a peer group, fatigued adolescents by themselves, and non-fatigued adolescents by themselves. The findings showed that cognitive fatigue and peer presence evinced independent effects on risk taking and sensitivity to rewards, but that these factors do not influence adolescent decision-making in an additive or synergistic fashion. To our surprise, being fatigued reduces (but does not eliminate) the effect of peers of risk taking. Moreover, the impact of peers on adolescent males' ability to learn from negative consequences is not compromised when adolescents are in a state of mental fatigue. Our results suggest that mental fatigue increases late adolescent males' reward sensitivity to the same extent as peer presence, but does not amplify the peer effect on risk-taking behavior. In this regard, grouping adolescents when they are fatigued may be less dangerous than when they are rested. Similarly, the added presence of peers does not further exacerbate the effect of fatigue on adolescent's reward- and risk-seeking inclinations. In fact, given peers' unique effect on adolescents' ability to learn from costly decisions, our findings suggest that seeking the presence of peers-which is often a rewarding experience in and of itself-may be an adaptive response to mitigate the impact of fatigue on decision making.

The effect of mental fatigue on the performance of Australian football specific skills amongst amateur athletes

Health has effects on children's academic performance. Qi deficiency is generally used to assess an individual's health in the Chinese traditional medicine theory. This study explores the effects of qi deficiency on children's academic performance and examines whether mental fatigue mediates these effects. A total of 550 students aged 10-13 in fifth-grade were surveyed in a big primary school in Sichuan Province in November 2023 using paper-pencil-based questionnaires. Qi deficiency and mental fatigue were assessed, and exam scores in Chinese and Mathematics were recorded. Pearson's correlation and linear regression analyses were used to test the mediation model and hypotheses. The fifth-grade students had mild qi deficiency (M = 2.09) and a mild state of mental fatigue (M = 2.38) on a five-point Likert scale. The average exam scores in Mathematics and Chinese were 70.07 and 74.44 points out of 100, respectively. Qi deficiency was associated with Mathematics scores (r = -0.37, p < 0.01) and Chinese scores (r = -0.30, p < 0.01), and mental fatigue (r = 0.47, p < 0.01). Furthermore, mental fatigue was associated with Mathematics scores (r = -0.46, p < 0.01) and Chinese scores (r = -0.34, p < 0.01). Linear regression analyses showed that qi deficiency significantly predicted Mathematics scores (β = -0.26, p < 0.01), Chinese scores (β = -0.19, p < 0.01), and mental fatigue (β = 0.41, p < 0.01). When qi deficiency was controlled for, mental fatigue significantly predicted Mathematics scores (β = -0.28, p < 0.01) and Chinese scores (β = -0.17, p < 0.01). The mediation model and hypotheses were well supported, indicating that mental fatigue mediated the influence of qi deficiency on academic performance of fifth-grade students. Furthermore, the mediation effect of mental fatigue on Mathematics scores was a little stronger than that on Chinese scores.

Evaluation of mental fatigue based on multipsychophysiological parameters and kernel learning algorithms

Mental fatigue is a key cause of chronic diseases and traffic accidents, which is difficult to be quantitatively evaluated. In order to non-intrusively detect fatigue state, an optical fiber sensing system is proposed, which is non-invasive and does not require direct contact with skin. The fiber sensor was fabricated through phase mask exposure method and packaged by sensitivity-enhanced structure, which can suppress transverse force and increase signal amplitude by 5%. A fatigue-inducing experiment was carried out, and the heartbeat signals of 20 subjects under different fatigue states were collected by the proposed sensing system. A series of heart rate variability indicators were calculated from the sensing signals, and their statistical significance for fatigue was analyzed. The experiment results showed that the values of SDNN and LF/HF increased significantly with subjects’ fatigue level. This study shows that the proposed fiber optic sensing system has practical value in fatigue state monitoring.

Mental fatigue (MF) is a common phenomenon in our daily lives. In the workplace, mental fatigue can increase the risk of human errors. Moreover, if it is not detected and handled correctly, it can cause various problems. Electroencephalogram (EEG) is one of many modalities that is widely used by researchers for detecting mental fatigue. However, due to the difficulty in provoking fatigue condition during the EEG measurement, this study proposed two experimental designs for detecting mental fatigue, the first design is by using physical induction (PI) and the 2nd design is by using mental induction (MI). We obtained the EEG signals from 20 healthy participants, from 14 channels of wireless EEG headset. Each participant was given four types of cognitive tests in the form of a computer game including Trail, Span, Stroop, and Arithmetic. The subjective measurement of fatigue condition was measured by using the Swedish Occupational Fatigue Inventory (SOFI) questionnaires. The EEG signal was extracted by using power percentage (PP) features of alpha ( $\alpha$ ), beta ( $\beta$ ), and theta ( $\theta$ ) bands of frequency from all channels. As for classification, we introduced the use Relevance Vector Machine (RVM) approach which is claimed to have better performance than SVM as the precedence method. According to the results, all of the cognitive tests has increased average value of response time (RT) and decreased correction score (CS) on post-induction compared to pre-induction. Another result showed that the best mental fatigue detection is obtained from mental induction rather than physical induction. The classification results demonstrate an accuracy of 93.7% (MI) and 92.6% (PI) are achieved by RVM approach. Furthermore, RVM has also less execution time compared to SVM.

It has been shown that the mental fatigue induced by prolonged self-regulation increases perception of effort and reduces performance during subsequent endurance exercise. However, the physiological mechanisms underlying these negative effects of mental fatigue are unclear. The primary aim of this study was to test the hypothesis that mental fatigue exacerbates central fatigue induced by whole-body endurance exercise. Twelve subjects performed 30 min of either an incongruent Stroop task to induce a condition of mental fatigue or a congruent Stroop task (control condition) in a random and counterbalanced order. Both cognitive tasks (CTs) were followed by a whole-body endurance task (ET) consisting of 6 min of cycling exercise at 80% of peak power output measured during a preliminary incremental test. Neuromuscular function of the knee extensors was assessed before and after CT, and after ET. Rating of perceived exertion (RPE) was measured during ET. Both CTs did not induce any decrease in maximal voluntary contraction (MVC) torque (p = 0.194). During ET, mentally fatigued subjects reported higher RPE (mental fatigue 13.9 ± 3.0, control 13.3 ± 3.2, p = 0.044). ET induced a similar decrease in MVC torque (mental fatigue –17 ± 15%, control –15 ± 11%, p = 0.001), maximal voluntary activation level (mental fatigue –6 ± 9%, control –6 ± 7%, p = 0.013) and resting twitch (mental fatigue –30 ± 14%, control –32 ± 10%, p < 0.001) in both conditions. These findings reject our hypothesis and confirm previous findings that mental fatigue does not reduce the capacity of the central nervous system to recruit the working muscles. The negative effect of mental fatigue on perception of effort does not reflect a greater development of either central or peripheral fatigue. Consequently, mentally fatigued subjects are still able to perform maximal exercise, but they are experiencing an altered performance during submaximal exercise due to higher-than-normal perception of effort.