Does the brain consume additional glucose during self-control tasks?

Mental Fatigue and Sports Performance of Athletes: Theoretical Explanation, Influencing Factors, and Intervention Methods

Mental fatigue is an important factor affecting athletes' performance. Explaining the effects of mental fatigue on sports performance from a theoretical point of view can help us deeply understand the interconnection between mental fatigue and sports performance and conduct effective interventions based on this. Combining the relevant literature in China and abroad reveals that the current academic theories on the mechanism of sports fatigue include motivational control theory, underload theory, neural waste disposal hypothesis, and resource depletion theory. The effects of mental fatigue on performance are reflected in aerobic endurance, sports decision-making, tactical performance, and technical performance. Current coping strategies for mental fatigue include physiological coping strategies based on nutrition (caffeine), odor, and noninvasive neuromodulation techniques and psychological and behavioral coping strategies based on music and positive thinking.

An Integrated Perspective of Effort and Perception of Effort

Effort and the perception of effort (PE) have been extensively studied across disciplines, resulting in multiple definitions. These inconsistencies block scientific progress by impeding effective communication between and within fields. Here, we present an integrated perspective of effort and PE that is applicable to both physical and cognitive activities. We define effort as the energy utilized to perform an action. This definition can be applied to biological entities performing various voluntary or involuntary activities, irrespective of whether the effort contributes to goal achievement. Then, we define PE as the instantaneous experience of utilizing energy to perform an action. This definition builds on that of effort without conflating it with other subjective experiences. We explore the nature of effort and PE as constructs and variables and highlight key considerations in their measurement. Our integrated perspective aims to facilitate a deeper understanding of these constructs, refine research methodologies, and promote interdisciplinary collaborations.

Working hard but not tired? The influence of task valuation on mental fatigue, effort investment, and task performance

It has been demonstrated in previous studies that prolonged mental effort exertion evokes mental fatigue and leads to impairments in task performance. In the current investigation, we aimed to test the hypothesis that mental fatigue depends on motivational processes and can be influenced by task valuation. In two studies, we experimentally manipulated the value of the task by financial rewards (Study 1) and the sense of autonomy (Study 2). Contrary to our predictions, those manipulations did not influence the main dependent variables. We also introduced additional rewards after prolonged effort exertion. In line with our expectations, the results showed that mental fatigue increases with time spent on effortful tasks. Importantly, however, mental fatigue decreases when the value of the task rises. This effect is accompanied by stronger effort engagement and improvement in task performance. The findings support the motivational theories of mental effort and fatigue, showing that mental fatigue might serve as a signal of diminishing value of the ongoing task.

Changes in pupil size track self-control failure

People are more likely to perform poorly on a self-control task following a previous task requiring self-control (ego-depletion), but the mechanism for this effect remains unclear. We used pupillometry to test the role of attentional effort in ego-depletion. We hypothesized that an elevated pupil diameter (PD)-a common physiological measure of effort-during an initial task requiring self-control should be negatively associated with performance on a subsequent control task. To test this hypothesis, participants were first assigned to either a high- or low-demand attention task (manipulation; a standard ego-depletion paradigm), after which all participants completed the same Stroop task. We then separately extracted both sustained (low-frequency) and phasic (high-frequency) changes in PD from both tasks to evaluate possible associations with lapses of cognitive control on the Stroop task. We first show that in the initial task, sustained PD was larger among participants who were assigned to the demanding attention condition. Furthermore, ego-depletion effects were serially mediated by PD: an elevated PD response emerged rapidly among the experimental group during the manipulation, persisted as an elevated baseline response during the Stroop task, and predicted worse accuracy on incongruent trials, revealing a potential indirect pathway to ego-depletion via sustained attention. Secondary analyses revealed another, independent and direct pathway via high levels of transient attentional control: participants who exhibited large phasic responses during the manipulation tended to perform worse on the subsequent Stroop task. We conclude by exploring the neuroscientific implications of these results within the context of current theories of self-control.

Integrated control of non-motor and motor efforts during perceptual decision-making and action execution: a pilot study

Humans daily life is characterized by a succession of voluntary actions. Since energy resources are limited, the ability to invest the appropriate amount of effort for selecting and executing these actions is a hallmark of adapted behavior. Recent studies indicate that decisions and actions share important principles, including the optimization of their duration when the context requires it. In the present pilot study, we test the hypothesis that the management of effort-related energy resources is shared between decision and action too. Healthy human subjects performed a perceptual decision task where they had to choose between two levels of effort to invest in making the decision (i.e. two levels of perceptual difficulty), and report it with a reaching movement. Crucially, the movement accuracy requirement gradually increased from trial to trial depending on participants' decision performance. Results indicate an overall moderate and non-significant impact of the increasing motor difficulty on the choice of the non-motor (decision) effort to invest in each trial and on decision performance. By contrast, motor performance strongly decreased depending on both the motor and decisional difficulties. Together, the results support the hypothesis of an integrated management of the effort-related energy resources between decision and action. They also suggest that in the present task, the mutualized resources are primarily allocated to the decision-making process to the detriment of movements.

Is all mental effort equal? The role of cognitive demand-type on effort avoidance

Humans are often termed "cognitive misers" for their aversion to mental effort. Both in and outside the laboratory people often show preferences for low-effort tasks and are willing to forgo financial reward to avoid more demanding alternatives. Mental effort, however, does not seem to be ubiquitously avoided: people play crosswords, board games, and read novels, all as forms of leisure. While such activities undoubtedly require effort, the type of cognitive demands they impose appear markedly different from the tasks typically used in psychological research on mental effort (e.g., N-Back, Stroop Task, vigilance tasks). We investigate the effect disparate demands, such as tasks which require problem solving (e.g., solve the missing number: 1, 3, 7, 15, 31,?) compared to those which require rule-implementation (e.g., N-Back task), have on people's aversion to or preference for increased mental effort. Across four experiments using three different tasks, and a mixture of online and lab-based settings, we find that aversion to effort remains largely stable regardless of the types of cognitive demands a task imposes. The results are discussed in terms of other factors that might induce the pursuit of mental effort over and above the type of cognitive demands imposed by a task.

Neural fatigue by passive induction: repeated stimulus exposure results in cognitive fatigue and altered representations in task-relevant networks

Cognitive fatigue is defined by a reduced capacity to perform mental tasks. Despite its pervasiveness, the underlying neural mechanisms remain elusive. Specifically, it is unclear whether prolonged effort affects performance through alterations in over-worked task-relevant neuronal assemblies. Our paradigm based on repeated passive visual stimulation discerns fatigue effects from the influence of motivation, skill and boredom. We induced performance loss and observed parallel alterations in the neural blueprint of the task, by mirroring behavioral performance with multivariate neuroimaging techniques (MVPA) that afford a subject-specific approach. Crucially, functional areas that responded the most to repeated stimulation were also the most affected. Finally, univariate analysis revealed clusters displaying significant disruption within the extrastriate visual cortex. In sum, here we show that repeated stimulation impacts the implicated brain areas' activity and causes tangible behavioral repercussions, providing evidence that cognitive fatigue can result from local, functional, disruptions in the neural signal induced by protracted recruitment.

Neural mechanisms underlying state mental fatigue: a systematic review and activation likelihood estimation meta-analysis

Sustained performance of cognitive tasks could lead to the development of state mental fatigue characterized by subjective sensation of mental weariness and decrease in cognitive performance. In addition to the occupational hazards associated with mental fatigue, it can also affect physical performance reducing endurance, balance, and sport-specific technical skills. Similarly, mental fatigue is a common symptom in certain chronic health conditions such as multiple sclerosis affecting quality of life of the patients. Despite its widely acknowledged negative impact, the neural mechanisms underlining this phenomenon are still not fully understood. We conducted a systematic review and activation likelihood estimation (ALE) meta-analysis of functional neuroimaging studies investigating the effect of mental fatigue due to time-on-task (TOT) on brain activity to elucidate the possible underlying mechanisms. Studies were included if they examined change in brain activity induced by experimental mental fatigue (TOT effect) or investigated the relationship between brain activity and subjective mental fatigue due to TOT. A total of 33 studies met the review's inclusion criteria, 13 of which were included in meta-analyses. Results of the meta-analyses revealed a decrease in activity with TOT in brain areas that constitute the cognitive control network. Additionally, an increased activity with TOT, as well as negative relationship with subjective mental fatigue was found in parts of the default mode network of the brain. The changes in cognitive control and the default mode networks of the brain due to state mental fatigue observed in this study were discussed in relation to the existing theories of mental fatigue.

The Counteractive Effect of Self-Regulation-Based Interventions on Prior Mental Exertion: A Systematic Review of Randomised Controlled Trials

BACKGROUND

Many investigations have been performed on the effects of mental exertion that consumes self-regulatory resources and then affects physical and/or cognitive performance later on. However, the effect of manipulating self-regulation and interventions to attenuate this negative effect remains unclear. Moreover, there is continuous controversy regarding the resource model of self-regulation.

OBJECTIVE

We conducted a systematic review to assess the literature on manipulating self-regulation based on four ingredients (standard, monitoring, strength, and motivation) in order to counter mental exertion and improve physical and/or cognitive performance. The results provide more insight into the resource model.

METHOD

A thorough search was conducted to extract the relevant literature from several databases, as well as Google Scholar, and the sources from the references were included as grey literature. A self-regulation intervention compared to a control condition, a physical and/or cognitive task, and a randomised controlled trial were selected.

RESULT

A total of 39 publications were included. Regarding the four components of self-regulation, the interventions could mainly be divided into the following: (i) standard: implementation intervention; (ii) monitoring: biofeedback and time monitoring; (iii) strength: repeated exercise, mindfulness, nature exposure, and recovery strategies; (iv) motivation: autonomy-supportive and monetary incentives. The majority of the interventions led to significant improvement in subsequent self-regulatory performance. In addition, the resource model of self-regulation and attention-restoration theory were the most frequently used theories and supported relevant interventions.

CONCLUSION

In line with the resource model, manipulating the four components of self-regulation can effectively attenuate the negative influence of mental exertion. The conservation proposed in the strength model of self-regulation was supported in the current findings to explain the role of motivation in the self-regulation process. Future studies can focus on attention as the centre of the metaphorical resource in the model.

Hangry in the field: An experience sampling study on the impact of hunger on anger, irritability, and affect

The colloquial term “hangry” refers to the notion that people become angry when hungry, but very little research has directly determined the extent to which the relationship between hunger and negative emotions is robust. Here, we examined associations between everyday experiences of hunger and negative emotions using an experience sampling method. Sixty-four participants from Central Europe completed a 21-day experience sampling phase in which they reported their hunger, anger, irritability, pleasure, and arousal at five time-points each day (total = 9,142 responses). Results indicated that greater levels of self-reported hunger were associated with greater feelings of anger and irritability, and with lower pleasure. These findings remained significant after accounting for participant sex, age, body mass index, dietary behaviours, and trait anger. In contrast, associations with arousal were not significant. These results provide evidence that everyday levels of hunger are associated with negative emotionality and supports the notion of being “hangry”.

Can Self-Regulatory Strength Training Counter Prior Mental Exertion? A Systematic Review of Randomized Controlled Trials

Background

Prior mental exertion consumes self-regulation and influences any subsequent physical or cognitive performance according to the strength model of self-regulation. However, the counteractive effect of self-regulatory strength training remains unclear.

Objective

This study aims to report a comprehensive systematic review investigating self-regulatory strength training programmes on physical or cognitive performance.

Methods

To select relevant studies from the available literature, a thorough search was conducted on PubMed, Web of Science, EBSCOhost (CENTRAL, Psychology and Behavioral Sciences Collection, SPORTDicus), Scopus, and Google Scholar, as well as the sources of reference for gray literature. Only randomized controlled trials involving healthy humans, strength-based self-regulation training programmes with comparable protocols, and a physical or cognitive task associated with the study were selected for the current review. The Grading of Recommendations Assessment Development and Evaluation (GRADE) framework was used to develop the summary of findings.

Results

Twelve articles were included based on the selection criteria. Evidence certainty for outcomes was graded as either low or very low level. The majority of the studies reported that self-regulatory strength training programmes can significantly counter prior mental exertion and decrement of performance, while only one study did not find such improvement. According to the strength model, a period of training increased the ‘self-regulatory muscle.'

Conclusion

Strength is an important ingredient in the resource model of self-regulation and can be trained to counter prior mental exertion and improve subsequent physical and cognitive performance. The training effects are cross-domain (e.g., emotional and cognitive domains; higher and lower levels of executive functions). However, motivation plays a key role to mobilize this resource. Future studies should examine the mechanism that underlies the strength.

Systematic Review Registration

https://inplasy.com/inplasy-2022-1-0060/, identifier: INPLASY202210060.

Causal role of frontal-midline theta in cognitive effort: a pilot study

Frontal-midline theta (FMT) oscillations are increased in amplitude during cognitive control tasks. Since these tasks often conflate cognitive control and cognitive effort, it remains unknown if FMT amplitude maps onto cognitive control or effort. To address this gap, we utilized the glucose facilitation effect to manipulate cognitive effort without changing cognitive control demands. We performed a single-blind, crossover human study in which we provided participants with a glucose drink (control session: volume-matched water) to reduce cognitive effort and improve performance on a visuospatial working memory task. Following glucose consumption, participants performed the working memory task at multiple time points of a 3-h window to sample across the rise and fall of blood glucose. Using high-density electroencephalography (EEG), we calculated FMT amplitude during the delay period of the working memory task. Source localization analysis revealed that FMT oscillations originated from bilateral prefrontal cortex. We found that glucose increased working memory accuracy during the high working memory load condition but decreased FMT amplitude. The decrease in FMT amplitude coincided with both peak blood glucose elevation and peak performance enhancement for glucose relative to water. Therefore, the positive association between glucose consumption and task performance provided causal evidence that the amplitude of FMT oscillations may correspond to cognitive effort, rather than cognitive control. Due to the COVID-19 pandemic, data collection was terminated prematurely; the preliminary nature of these findings due to small sample size should be contextualized by rigorous experimental design and use of a novel causal perturbation to dissociate cognitive effort and cognitive control.NEW & NOTEWORTHY We investigated whether frontal-midline theta (FMT) oscillations tracked with cognitive control or cognitive effort by simultaneous manipulation of cognitive control demands in a working memory task and causal perturbation of cognitive effort using glucose consumption. Facilitation of performance from glucose consumption corresponded with decreased FMT amplitude, which provided preliminary causal evidence for a relationship between FMT amplitude with cognitive effort.

A Schema-Activation Approach to Failure and Success in Self-Control

Numerous studies confirm the so-called ego depletion effect (i.e., self-control is impaired after an initial unrelated self-control task). During recent years, the criticism on this limited-resource approach to willpower has increased, and alternative models have been developed. I argue that the existing models cannot explain the variety of results found in the ego depletion literature and introduce the schema model of self-control. Referring to related schema conceptions (i.e., illness schemas and emotion schemas), I posit that the processes that cause ego depletion effects occur around the activation of the fatigue/decreased vitality schema. This schema becomes activated via the registration of behavioral and physiological changes related to exercising self-control. The activation of the schema should instigate the motivation to conserve energy and, therefore, cause reduced effort and decreased performance in a subsequent self-control task. Moderator variables (e.g., energy supply) should influence the (non)activation of the fatigue/decreased vitality schema or its consequences.

Self-Control and Exercise: A Review of the Bi-Directional Relationship

Self-control has been defined as the mental capacity of an individual to alter, modify, change or override their impulses, desires, and habitual responses. In this review, we will discuss the bi-directional nature of the relationship between self-control and exercise. In brief, higher levels of trait self-control have been associated with greater exercise performance and adherence; whilst the depletion of state self-control has been shown to decrease performance and persistence on subsequent exercise tasks requiring self-control. In the opposite direction, long-term participation in exercise (and improved physical fitness) has been demonstrated to enhance self-control. Furthermore, an acute bout of exercise has been shown to enhance subsequent self-control, particularly when the exercise is of a moderate intensity and requires some degree of cognitive engagement. Throughout, when discussing each of these relationships, evidence will be drawn from other aspects of the review, where appropriate, to enhance our understanding of the observed effects. Finally, recommendations for future research will be made; including the importance of considering the bi-directional nature of the relationship, given that this has implications for our understanding of both self-control and exercise performance and adherence.

The Effects of Self-Control on Glucose Utilization in a Hyperinsulinemic Euglycemic Glucose Clamp

Abstract. Background. The glucose hypothesis of self-control posits that acts of self-control may draw upon glucose as a source of energy, leading to a decrease in blood glucose levels after exerting self-control, mirroring the temporary depletion of self-control, but supporting evidence is mixed and inconclusive. This might partly be due to using methods that are not suitable to reliably quantify glucose utilization. Aims. We aimed at examining whether self-control exertion leads to an increase in glucose utilization. Method. In a sample of N = 30 healthy participants (50% women, age 26.5 ± 3.5 years) we combined a hyperinsulinemic euglycemic glucose clamp (a well-established and validated procedure in experimental endocrinology to reliably quantify systemic glucose utilization) with a standard self-control dual-task paradigm. In the first task, the experimental group completed a variation of a paper-and-pencil crossing out letter task (COLT) that demanded self-control; the control group completed a variation of the COLT that did not demand self-control. The second task for both groups was a computerized two-color word Stroop which demanded self-control. Results. We did not find a significant main effect for time, nor a time × group interaction with respect to glucose utilization, which indicates that glucose utilization did not differ significantly over time or between groups. Limitations. Due to the time-consuming and complicated clamp method, our sample was rather small. Conclusion. Our results revealed little evidence for the notion that self-control efforts are associated with a relevant increase in peripheral glucose utilization.

Mental Fatigue Impairs Endurance Performance: A Physiological Explanation

Mental fatigue reflects a change in psychobiological state, caused by prolonged periods of demanding cognitive activity. It has been well documented that mental fatigue impairs cognitive performance; however, more recently, it has been demonstrated that endurance performance is also impaired by mental fatigue. The mechanism behind the detrimental effect of mental fatigue on endurance performance is poorly understood. Variables traditionally believed to limit endurance performance, such as heart rate, lactate accumulation and neuromuscular function, are unaffected by mental fatigue. Rather, it has been suggested that the negative impact of mental fatigue on endurance performance is primarily mediated by the greater perception of effort experienced by mentally fatigued participants. Pageaux et al. (Eur J Appl Physiol 114(5):1095-1105, 2014) first proposed that prolonged performance of a demanding cognitive task increases cerebral adenosine accumulation and that this accumulation may lead to the higher perception of effort experienced during subsequent endurance performance. This theoretical review looks at evidence to support and extend this hypothesis.

Neuro-computational Impact of Physical Training Overload on Economic Decision-Making

Overtraining syndrome is a form of burnout, defined in endurance athletes by unexplained performance drop associated with intense fatigue sensation. Our working hypothesis is that the form of fatigue resulting from physical training overload might share some neural underpinnings with the form of fatigue observed after prolonged intellectual work, which was previously shown to affect the cognitive control brain system. Indeed, cognitive control may be required to prevent any impulsive behavior, including stopping physical effort when it hurts, despite the long-term goal of improving performance through intense training. To test this hypothesis, we induced a mild form of overtraining in a group of endurance athletes, which we compared to a group of normally trained athletes on behavioral tasks performed during fMRI scanning. At the behavioral level, training overload enhanced impulsivity in economic choice, which was captured by a bias favoring immediate over delayed rewards in our computational model. At the neural level, training overload resulted in diminished activation of the lateral prefrontal cortex, a key region of the cognitive control system, during economic choice. Our results therefore provide causal evidence for a functional link between enduring physical exercise and exerting cognitive control. Besides, the concept of cognitive control fatigue bridges the functional consequences of excessive physical training and intellectual work into a single neuro-computational mechanism, which might contribute to other clinical forms of burnout syndromes.

The Perception of Available Resources Influences the After-Effect of Cognitive Control on Cognitive Performance and Pain

Abstract. In two experiments, we investigated the impact of perceived available cognitive resources using a sequential-task paradigm. First, participants worked on an easy or difficult cognitive task. Then, they received a cue suggesting that their cognitive resources were still optimal or they did not receive any information on their resources. Subsequently, they worked on a second difficult cognitive task (Experiment 1) or received painful electrical stimulations (Experiment 2). We predicted that the cue on optimal resources would neutralize the effect of the first difficult task on subsequent cognitive performance and pain. Overall, results supported our predictions. We interpret these findings as showing an important role of perceived available resources in the after-effect induced by the sequential-task paradigm.

Sweet Nothings

Abstract. Prior research has suggested that circulating levels of glucose in the bloodstream help to determine success at self-control. However, this idea has been challenged on multiple grounds. The current research added new evidence to the debate by testing (1) the extent to which exercising self-control reduces blood glucose levels, (2) whether consuming glucose, rinsing the mouth with glucose, or consuming aspartame (a sugar substitute) increases blood glucose levels, and (3) the extent to which measured blood glucose levels relate to emotional responding, delay discounting, and cognitive control, respectively. We found no evidence that blood glucose levels influence or are influenced by self-control.

The Past, Present, and Future of Ego Depletion

Abstract. At the center of social psychology just a few years ago, ego depletion is now widely seen as a controversial topic, one of the chief victims of the replication crisis. Despite over 600 studies of apparent support, many are now asking if ego depletion is even real. Here, we comment on the articles included in this Special Issue: Ego Depletion and Self-Control: Conceptual and Empirical Advances. Specifically, we delineate the contributions and limitations of these articles by embedding them in a brief history of ego depletion, describing the current state of uncertainty about ego depletion’s scientific status, and outlining necessary steps for the study of ego depletion to have a healthy future. To us, the most troubling aspect of this controversy is not what it suggests about ego depletion, but what it suggests about social psychology more broadly. If the mere existence of ego depletion is seriously doubted by many, what can be confidently regarded as real in social psychology? By increasing the precision of our theories, continuously validating our manipulations and measures, and practicing the full suite of open science practices, we have the potential to identify legitimate and robust effects and build a cumulative and trustworthy psychological science.

Listening effort: Are we measuring cognition or affect, or both?

Listening effort is increasingly recognized as a factor in communication, particularly for and with nonnative speakers, for the elderly, for individuals with hearing impairment and/or for those working in noise. However, as highlighted by McGarrigle et al., International Journal of Audiology, 2014, 53, 433-445, the term "listening effort" encompasses a wide variety of concepts, including the engagement and control of multiple possibly distinct neural systems for information processing, and the affective response to the expenditure of those resources in a given context. Thus, experimental or clinical methods intended to objectively quantify listening effort may ultimately reflect a complex interaction between the operations of one or more of those information processing systems, and/or the affective and motivational response to the demand on those systems. Here we examine theoretical, behavioral, and psychophysiological factors related to resolving the question of what we are measuring, and why, when we measure "listening effort." This article is categorized under: Linguistics > Language in Mind and Brain Psychology > Theory and Methods Psychology > Attention Psychology > Emotion and Motivation.

Regulation strategies and their impact on subsequent response inhibition: the moderating role of the self-control trait

Background

Much research has shown that effortful acts of self-control temporarily impair its subsequent exertion. The aim of our experi-ment was to examine whether this effect, called ego depletion, is influenced by application of certain strategies that help people to overcome impulses. Another purpose of our research was to investigate the role of self-control as a trait in this area. We fo-cused on amusement regulation because of its importance in everyday life.

Participants and procedure

Participants (N = 90) completed the Self-Control Scale (NAS-50) and were then asked to rate humorous cartoons (Task 1) while inducing the following self-regulatory strategies suggested by the instructions: cognitive change, response inhibition, or none (between-subjects manipulation). Subsequently, participants performed the Stop Signal Task (Task 2).

Results

The results indicate that the depletion effect is absent unless trait self-control is included in the analysis. We observed the interac-tion between the self-control trait and the effectiveness of the adopted self-regulatory strategy. Participants with poor self-control did not differ in their performance in Task 2, regardless of the adopted strategy. With the increase in the self-control trait, we observed differences in Task 2 that indicated that the cognitive change strategy guarded against depletion in participants with a medium level of self-control. Participants with a high self-control trait level obtained better scores in both regulatory groups, compared to the condition without any strategy.

Conclusions

We discuss these findings in terms of the competing explanations of the ‘ego depletion’ effect, as well as in terms of the trait versus state approach to self-control.

Does Depleting Self-Control Result in Poorer Vigilance Performance?

OBJECTIVE

To investigate whether depleting self-control prior to vigilance results in a steeper vigilance decrement.

BACKGROUND

The resource-control theory of vigilance asserts that an inherent bias toward self-generated mind-wandering draws attentional resources away from the primary task. This study seeks to test whether depleting self-control, the potential mechanism of self-generated mind-wandering, results in poorer vigilance performance.

METHOD

This study featured a between-subjects design where participants either completed a typing task that depleted self-control resources or a standard typing task that did not require self-control before performing a vigilance task. In the self-control depletion condition, participants typed a passage while omitting any "e" and "space" keys. In the standard typing task, participants typed the same passage without skipping any keys. Following both typing tasks, participants in both conditions completed an identical 12-min vigilance task.

RESULTS

Results demonstrated decreased accuracy and increased reaction times over time for both groups. Depleting self-control did not result in significant differences in accuracy, reaction time, nor a steeper vigilance decrement.

CONCLUSION

These results provide evidence against resource-control theory and self-control as an explanation for vigilance, and provide further support for cognitive resource theory as the predominant explanation for vigilance impairments.

APPLICATION

It is still unclear exactly what constitutes a "resource." A better understanding of the nature of these resources can help researchers and practitioners identify how they can be replenished, which could enhance human performance in situations requiring vigilance such as baggage screening.

The Effect of Preceding Self-Control on Prosocial Behaviors: The Moderating Role of Awe

The exertion of self-control is known to result in subsequent detrimental effects on prosocial behaviors. Moreover, certain studies have demonstrated that positive emotions could drive people to allocate more attentional resources for conducting prosocial behaviors. However, whether and how awe - one important type of positive incidental emotion - moderates the effect of exerting self-control on subsequent prosocial behaviors remains unclear yet. The anonymous economic dictator game is an effective index of prosocial behaviors. We examined the influence of exerting self-control on prosocial behavior and the moderating role of awe on the effect of exerting self-control on prosocial behaviors in two experiments (N = 280). We adopted the incongruent Stroop task to induce the exertion of self-control and participants were required to allocate money to others in the anonymous dictator game (Experiment 1). We used the narrative recall task paradigm to elicit the emotion of awe during the interval between Stroop tasks and the dictator game (Experiment 2). Results indicated that the exertion of self-control was detrimental to prosocial behaviors and awe weakened the detrimental effects of exerting self-control on prosocial behavior. We interpreted these results in terms of the protective inhibition of self-regulation and motivation (PRISM) model.

Ego depletion and the use of force: Investigating the effects of ego depletion on police officers' intention to use force

The current study aims to investigate corresponding self-control and self-control failures that are the result of ego depletion and its impact on police officers' decision to use force. For that purpose, a total of 200 German police recruits were randomly assigned to either an experimental or control group. Ego depletion was manipulated using the "e" crossing task. Participants then worked through a video-based scenario exercise, in which they encountered a provocative citizen. They were required to indicate the time that they would take to resort to using force to resolve the situation. Results showed that ego depleted officers intended to use force earlier than controls. This indicates that circumstances that produce ego depletion could lead to the inappropriate use of force by reducing self-control. This has major implications for the police use of force and how we understand police officers' decision making in response to provocation.

Resource Signaling via Blood Glucose in Embodied Decision Making

Food, money, and time are exchangeable resources essential for survival and reproduction. Individuals live within finite budgets of these resources and make tradeoffs between money and time when making intertemporal choices between an immediate smaller reward and a delayed lager reward. In this paper, I examine signaling functions of blood glucose in regulating behaviors related to resource regulations beyond caloric metabolisms. These behavioral regulations include choices between energy expenditure and energy conservation, monetary intertemporal choices, and self-control in overcoming temptations. I begin by comparing potential embodied signals for resource forecasting and proactive decision making in terms of their pros and cons as a signal for regulating both metabolism and behavioral decision making and self-control. Based on this analysis, circulating glucose emerges as not only the designated fuel for brain metabolism but also a privileged resource forecasting signal for regulating immediate, short-term, and long-term behavioral adaptations to the resource budget of the decision maker. In the context of an on-going debate between the limited resource model and the motivation accounts of behavioral effects of blood glucose, I propose a dual functions (caloric provision and resource forecasting) and dual signaling (glucose taste and ingestion) hypothesis of circulating glucose in resource management, and provide behavioral and neurophysiological evidence of the separate effects of glucose taste to motivate effort for resource acquisition and glucose ingestion to promote resource conservation and future orientation. Accumulating evidence indicates that the body is able to detect fake signals of non-caloric sweeteners and react to such "caloric crisis" with an enhanced preference for immediate rewards over future rewards, revealing the wisdom of the body.

Bridging Exercise Science, Cognitive Psychology, and Medical Practice: Is "Cognitive Fatigue" a Remake of "The Emperor's New Clothes"?

Fatigue is such a multifaceted construct it has sprouted specific research fields and experts in domains as different as exercise physiology, cognitive psychology, human factors and engineering, and medical practice. It lacks a consensus definition: it is an experimental concept, a symptom, a risk, a cause (e.g., of performance decrement) and a consequence (e.g., of sleep deprivation). This fragmentation of knowledge leads to slower dissemination of novel insights, and thus to a poorer research. Indeed, what may seem as a novel result in one field, may very well be old news in another, hence leading to this "innovation" being a scientific equivalent to the emperor's new clothes. The current paper aims to describe the common denominator in the different areas of expertise where fatigue is investigated. Indeed, rather than focusing on the differences in semantics and conceptualization, we hope that identifying common concepts may be inductive of easier multidisciplinary research. Considering the vastness of fatigue research in all areas identified as relevant-cognitive science, exercise physiology, and medical practice, this analysis has not the ambition to be an exhaustive review in all domains. We have reviewed the fatigue concepts and research in these areas and report the ones that are used to describe the proposed common model to be further investigated. The most promising common feature to cognitive science, exercise physiology and clinical practice is the notion of "perceived effort." This allows to account for interindividual differences, as well as for the situational variations in fatigue. It is applicable to both mental and physical constructs. It integrates motivational and emotional dimensions. It overcomes current polemics in various research fields, and it does not draw on any semantic ambiguity. We thus suggest a new model of fatigue and performance, whether this performance is mental or physical; and whether it is in a clinical range or relates to optimal functioning.

Drive in Sports: How Mental Fatigue Affects Endurance Performance

Performance in endurance sports relies on athletes' drive, which is the sum of all factors pushing athletes to exert effort during exercise. Mental fatigue can influence endurance performance by decreasing athletes' drive to exercise. From a psychological point of view, mental fatigue has two separate components: it can affect drive by increasing the perceived effort necessary for a given task ("I cannot do this, I am too exhausted"), or by decreasing the perceived value of the reward that can be obtained ("I do not want to do this, it is not worth it"). Neurophysiological theories confirm this dual nature of mental fatigue. It is suggested that mental fatigue can activate the inhibition centers of the brain, increasing perceived effort for a given task, hence decreasing drive and willingness to act. On the other hand, it may also deactivate facilitative brain centers (normally responsible for motivated behavior and increased drive toward a reward), also resulting in decreased drive. In this Perspective we will adopt a multidimensional approach, describing how mental fatigue interacts with drive and performance in endurance exercise. We aim to show how mental fatigue affects endurance performance via two main mechanisms: perceived effort and reward. We will study the interaction between mental fatigue and other factors impacting on drive, such as perceived exertion and motivation, and examine how these factors combined result in athletes' exercise behavior (such as pacing) and performance. This will provide researchers, coaches, and athletes with useful tools in order to understand, influence and enhance athletes' drive in exercise, which is of high relevance in elite endurance sports, where mental fatigue, motivation, and stakes all are of the highest level.

Psychophysiological measurement of affective responses during speech perception

When people make decisions about listening, such as whether to continue attending to a particular conversation or whether to wear their hearing aids to a particular restaurant, they do so on the basis of more than just their estimated performance. Recent research has highlighted the vital role of more subjective qualities such as effort, motivation, and fatigue. Here, we argue that the importance of these factors is largely mediated by a listener's emotional response to the listening challenge, and suggest that emotional responses to communication challenges may provide a crucial link between day-to-day communication stress and long-term health. We start by introducing some basic concepts from the study of emotion and affect. We then develop a conceptual framework to guide future research on this topic through examination of a variety of autonomic and peripheral physiological responses that have been employed to investigate both cognitive and affective phenomena related to challenging communication. We conclude by suggesting the need for further investigation of the links between communication difficulties, emotional response, and long-term health, and make some recommendations intended to guide future research on affective psychophysiology in speech communication.

Mental Work Requires Physical Energy: Self-Control Is Neither Exception nor Exceptional

The brain’s reliance on glucose as a primary fuel source is well established, but psychological models of cognitive processing that take energy supply into account remain uncommon. One exception is research on self-control depletion, where debate continues over a limited-resource model. This model argues that a transient reduction in self-control after the exertion of prior self-control is caused by the depletion of brain glucose, and that self-control processes are special, perhaps unique, in this regard. This model has been argued to be physiologically implausible in several recent reviews. This paper attempts to correct some inaccuracies that have occurred during debate over the physiological plausibility of this model. We contend that not only is such limitation of cognition by constraints on glucose supply plausible, it is well established in the neuroscience literature across several cognitive domains. Conversely, we argue that there is no evidence that self-control is special in regard to its metabolic cost. Mental processes require physical energy, and the body is limited in its ability to supply the brain with sufficient energy to fuel mental processes. This article reviews current findings in brain metabolism and seeks to resolve the current conflict in the field regarding the physiological plausibility of the self-control glucose-depletion hypothesis.

The feeling of effort during mental activity

The feeling of effort is familiar to most, if not all, humans. Prior research shows that the feeling of effort shapes judgments (e.g., of agency) and decisions (e.g., to quit the current task) in various ways, but the proximal causes of the feeling of effort are not well understood. In this research, I address these proximal causes. In particular, I conducted two preregistered experiments in which participants performed a difficult vs. easy cognitive task, while I measured effort-related phenomenology (feeling of effort) and physiology (pupil dilation) on a moment-to-moment basis. In both experiments, difficult tasks increased the feeling of effort; however, this effect could not be explained by concurrent increases in physiological effort. To explain these findings, I suggest that the feeling of effort during mental activity stems from the decision to exert physiological effort, rather than from physiological effort itself.

Effects of blood glucose on delay discounting, food intake and counterregulation in lean and obese men

BACKGROUND

Delay discounting as a measure of impulsivity has been shown to be higher in obesity with an association of increased food intake. Moreover, obese humans showed a higher wanting for high-calorie food than lean men when blood glucose concentrations were low. First studies linking blood glucose levels to delay discounting yielded mixed results. We hypothesized that obese people - in comparison to lean men - have a relative lack of energy, especially when blood glucose levels are low, that results in higher levels of delay discounting, food intake and hormonal counterregulation.

METHODS

We investigated 20 lean and 20 obese healthy young men in a single-blind balanced cross-over design. With a standardized glucose clamp technique, subjects underwent a hypoglycemic state in one condition and a euglycemic state in the control condition. Regularly, blood was sampled for assessment of hormonal status, and questionnaires were filled out to assess delay discounting and symptom awareness. After normalizing blood glucose concentrations, subjects were free to eat from a standardized test buffet, followed by a snack test.

RESULTS

Delay discounting was higher in obese than in lean men throughout experiments (p < 0.03). However, we did not observe significant discounting differences between glucose conditions (p > 0.1). Furthermore, the discounting performance did not correlate with food intake from the test buffet or snack test (p > 0.3). As a response to hypoglycemia, hormonal counterregulation was pronounced in both weight groups (p < 0.03), but responses of ACTH, norepinephrine and glucagon were stronger in obese compared to lean men (p < 0.03). Also, intake from the high-calorie buffet after hypoglycemia compared to euglycemia was higher in obese subjects (p < 0.02) but comparable in lean men (p > 0.5).

CONCLUSIONS

Our data suggest that augmented delay discounting is a robust feature in obesity that is not linked to glucose levels or actual food intake. With our systematically controlled approach, combining performance in delay discounting with regard to distinct blood glucose levels, different weight groups, counterregulatory behavior and food intake, our results imply that delay discounting is not susceptible to fluctuations of blood glucose and do not support the assumption that a low body's energy content leads to increased impulsivity. Further replications including women and larger sample sizes are needed to corroborate our data.

Fairness, fast and slow: A review of dual process models of fairness

Fairness, the notion that people deserve or have rights to certain resources or kinds of treatment, is a fundamental dimension of moral cognition. Drawing on recent evidence from economics, psychology, and neuroscience, we ask whether self-interest is always intuitive, requiring self-control to override with reasoning-based fairness concerns, or whether fairness itself can be intuitive. While we find strong support for rejecting the notion that self-interest is always intuitive, the literature has reached conflicting conclusions about the neurocognitive systems underpinning fairness. We propose that this disagreement can largely be resolved in light of an extended Social Heuristics Hypothesis. Divergent findings may be attributed to the interpretation of behavioral effects of ego depletion or neurostimulation, reverse inference from brain activity to the underlying psychological process, and insensitivity to social context and inter-individual differences. To better dissect the neurobiological basis of fairness, we outline how future research should embrace cross-disciplinary methods that combine psychological manipulations with neuroimaging, and that can probe inter-individual, and cultural heterogeneities.

The Effects of Carbohydrates, in Isolation and Combined with Caffeine, on Cognitive Performance and Mood-Current Evidence and Future Directions

This review examines the effects of carbohydrates, delivered individually and in combination with caffeine, on a range of cognitive domains and subjective mood. There is evidence for beneficial effects of glucose at a dose of 25 g on episodic memory, but exploration of dose effects has not been systematic and the effects on other cognitive domains is not known. Factors contributing to the differential sensitivity to glucose facilitation include age, task difficulty/demand, task domain, and glucoregulatory control. There is modest evidence to suggest modulating glycemic response may impact cognitive function. The evidence presented in this review identifies dose ranges of glucose and caffeine which improve cognition, but fails to find convincing consistent synergistic effects of combining caffeine and glucose. Whilst combining glucose and caffeine has been shown to facilitate cognitive performance and mood compared to placebo or glucose alone, the relative contribution of caffeine and glucose to the observed effects is difficult to ascertain, due to the paucity of studies that have appropriately compared the effects of these ingredients combined and in isolation. This review identifies a number of methodological challenges which need to be considered in the design of future hypothesis driven research in this area.

Susceptibility to unconscious influences is unaffected by a challenging inhibitory task or mental exhaustion

Unconscious influences have been demonstrated in a variety of behavioural contexts, however, a key question remains - to what extent do such influences vary with our changing mental states? We examine whether a prior inhibitory challenge increases susceptibility to subliminal priming in a stem completion task employing neutral (Experiment 1) and reward salient terms (Experiment 2). Results show stem completions to be significantly influenced by unconscious priming, and the challenging inhibitory task (the Stroop) to be significantly more mentally exhausting than the control task. However, neither the degree of inhibitory challenge, trait self-control, nor task-related mental exhaustion significantly influenced unconscious priming. Bayesian analysis provides strong evidence that prior inhibitory challenge does not affect susceptibility to unconscious priming. The study supports the conclusion that unconscious processing can be independent of consciously experienced mental states and provides reassurance that inhibitory impairment, common to mood disorders, should not increase susceptibility to unconscious influences.

Does Short-Term Hunger Increase Trust and Trustworthiness in a High Trust Society?

We build on the social heuristics hypothesis, the literature on the glucose model of self-control, and recent challenges on these hypotheses to investigate whether individuals exhibit a change in degree of trust and reciprocation after consumption of a meal. We induce short-term manipulation of hunger followed by the trust game and a decision on whether to leave personal belongings in an unlocked and unsupervised room. Our results are inconclusive. While, we report hungry individuals trusting and reciprocating more than those who have just consumed a meal in a high trust society, we fail to reject the null with small number of observations (N = 101) and experimental sessions (N = 8). In addition, we find no evidence of short-term hunger having an impact on charitable giving or decisions in public good game.

Resource forecasting: Differential effects of glucose taste and ingestion on delay discounting and self-control

We tested a novel hypothesis that glucose taste acts as a signal for resource acquisition, motivating preference for immediate rewards while actual glucose ingestion prompts resource conservation, promoting future-orientated self-regulation. In Study 1, participants were engaged in a delay-discounting task and a grip-control task before and after a beverage intervention (glucose drink, water drink, or glucose mouth-rinse). Glucose ingestion decreased delay discounting, making larger-and-later rewards more attractive. In contrast, glucose rinse increased delay discounting. Water ingestion had none of the effects. In the grip-control task, only glucose ingestion improved the performance. Study 2 using fMRI revealed that glucose rinse and glucose ingestion resulted in distinct brain activational patterns. Compared to glucose rinse, glucose ingestion deactivated a few brain regions (e.g., the anterior cingulate gyrus and inferior frontal gyrus) that are previously shown to be more active when making more difficult intertemporal choices, suggesting that glucose ingestion eases the process of making intertemporal choice. In sum, our behavioral and neuroimaging findings together suggest a dual signaling role of glucose sensation and ingestion in regulating delay discounting and self-control.

Restoring Agency to the Human Actor

A cursory read of the social psychological literature suggests that when people find themselves in strong situations, they fail to display agency. The early classic studies of conformity, obedience, and bystander intervention, for example, are renowned for showing that when challenged by strong situational pressures, participants acquiesced—even if it meant abandoning their moral principles or disregarding their own sensory data. Later studies of learned helplessness, ego depletion, and stereotype threat echoed this “power of the situation” theme, demonstrating that exposure to (or the expectation of) a frustrating or unpleasant experience suppressed subsequent efforts to actualize goals and abilities. Although this work has provided many valuable insights into the influence of situational pressures, it has been used to buttress an unbalanced and misleading portrait of human agency. This portrait fails to recognize that situations are not invariably enemies of agency. Instead, strong situational forces often allow for, and may even encourage, expressions of human agency. We examine the nature, causes, and consequences of this phenomenon. We endorse a broader approach that emphasizes how responding to situational pressure can coexist with agency. This new emphasis should create greater convergence between social psychological models and the experience of agency in everyday life.

A temporary deficiency in self-control: Can heightened motivation overcome this effect?

Self‐control is important for everyday life and involves behavioral regulation. Self‐control requires effort, and when completing two successive self‐control tasks, there is typically a temporary drop in performance in the second task. High self‐reported motivation and being made self‐aware somewhat counteract this effect—with the result that performance in the second task is enhanced. The current study explored the relationship between self‐awareness and motivation on sequential self‐control task performance. Before employing self‐control in an antisaccade task, participants initially applied self‐control in an incongruent Stroop task or completed a control task. After the Stroop task, participants unscrambled sentences that primed self‐awareness (each started with the word “I”) or unscrambled neutral sentences. Motivation was measured after the antisaccade task. Findings revealed that, after exerting self‐control in the incongruent Stroop task, motivation predicted erroneous responses in the antisaccade task for those that unscrambled neutral sentences, and high motivation led to fewer errors. Those primed with self‐awareness were somewhat more motivated overall, but motivation did not significantly predict antisaccade performance. Supporting the resource allocation account, if one was motivated—intrinsically or via the manipulation of self‐awareness—resources were allocated to both tasks leading to the successful completion of two sequential self‐control tasks.

Glucose Increases Risky Behavior and Attitudes in People Low in Self-Control

Abstract. People low in self-control have a strong proclivity toward risk-taking. Risk-taking behavior provides an opportunity to obtain some form of reward. Glucose, on the other hand, seems to facilitate reward and goal-directed behavior. In a pilot study executed in the laboratory, we investigated whether consuming a glucose drink would increase risky behavior and attitudes in people low in self-control. Our findings revealed that a dose of glucose compared to placebo increased risk-taking on a behavioral and cognitive level in participants low in self-control but not in participants high in self-control. The findings may shed some light on the psychological underpinnings of glucose: By showing glucose’s association with high-risk behavior, they support the assumption of glucose driving a goal-directed motivation.