Cognitive performance is enhanced if one knows when the task will end

External workload and cognitive performance of a tactical military scenario-based field exercise

INTRODUCTION

Military personnel must manage a multitude of competing physiological and cognitive stressors while maintaining high levels of performance. Quantifying the external workload and cognitive demands of tactical military field exercises closely simulating operational environments, will provide a better understanding of stressors placed on personnel to inform evidence-based interventions.

METHODS

Thirty-one soldiers completing a dismounted 48 hours tactical field exercise, participated in the study. External workload was quantified using a wrist-worn triaxial accelerometer, with cognitive function (Go-/No-Go, N-back, psychomotor vigilance task and subjective workload ratings (NASA-TLX) assessed pre-exercise, mid-exercise and postexercise. Physical activity was described using Euclidian Norm Minus One (mg), with moderate vigorous physical activity (MVPA) and sedentary light physical activity (SLPA) as ≥ or <113 mg, respectively. Changes in general cognitive performance (total accuracy-speed trade-off (ASTO) % change) and function outcome variables (overall mean reaction time, ASTO and number of correct and missed responses) were calculated for each assessment from pre-exercise, to mid-exercise and postexercise.

RESULTS

For the exercise duration (50:12±02:06 hh:mm) participants spent more time completing SLPA compared with MVPA (1932±234 vs 1074±194 min; p<0.001), equating to 33% of the time spent completing MVPA. Overall cognitive performance decreased over the exercise (pre-to-post: -249). However, the largest decrement was observed pre-to-mid (-168). Perceived mental demand associated with the cognitive assessments significantly increased over the duration of the exercise (pre-: 33; mid-: 38 and post-: 51; χ2 F(2) = 26.7, p = <0.001, W=0.477) which could suggest that participants were able to attenuate a further decline in cognitive performance by investing more effort/mental resources when completing assessments.

CONCLUSION

The study successfully quantified the physical activity, and subsequent impact on cognitive function, in soldiers completing a 48 hours tactical field exercise. Further research is needed to better understand how physiological stressors interact with cognitive function during military operations.

Dysfunctional feedback processing in male methamphetamine abusers: Evidence from neurophysiological and computational approaches

Methamphetamine use disorder (MUD) as a major public health risk is associated with dysfunctional neural feedback processing. Although dysfunctional feedback processing in people who are substance dependent has been explored in several behavioral, computational, and electrocortical studies, this mechanism in MUDs requires to be well understood. Furthermore, the current understanding of latent components of their behavior such as learning speed and exploration-exploitation dilemma is still limited. In addition, the association between the latent cognitive components and the related neural mechanisms also needs to be explored. Therefore, in this study, the underlying neurocognitive mechanisms of feedback processing of such impairment, and age/gender-matched healthy controls are evaluated within a probabilistic learning task with rewards and punishments. Mathematical modeling results based on the Q-learning paradigm suggested that MUDs show less sensitivity in distinguishing optimal options. Additionally, it may be worth noting that MUDs exhibited a slight decrease in their ability to learn from negative feedback compared to healthy controls. Also through the lens of underlying neural mechanisms, MUDs showed lower theta power at the medial-frontal areas while responding to negative feedback. However, other EEG measures of reinforcement learning including feedback-related negativity, parietal-P300, and activity flow from the medial frontal to lateral prefrontal regions, remained intact in MUDs. On the other hand, the elimination of the linkage between value sensitivity and medial-frontal theta activity in MUDs was observed. The observed dysfunction could be due to the adverse effects of methamphetamine on the cortico-striatal dopamine circuit, which is reflected in the anterior cingulate cortex activity as the most likely region responsible for efficient behavior adjustment. These findings could help us to pave the way toward tailored therapeutic approaches.

A novel protocol to induce mental fatigue

Mental fatigue is a commonplace human experience which is the focus of a growing body of research. Whilst researchers in numerous disciplines have attempted to uncover the origins, nature, and effects of mental fatigue, the literature is marked by many contradictory findings. We identified two major methodological problems for mental fatigue research. First, researchers rarely use objective measures of mental fatigue. Instead, they rely heavily on subjective reports as evidence that mental fatigue has been induced in participants. We aimed to develop a task which led to not only a subjective increase in mental fatigue, but a corresponding performance decrement in the mentally fatiguing task as an objective measure. Secondly, current mental fatigue paradigms have low ecological validity - in most prior studies participants have been fatigued with a single repetitive task such as the n-back or Stroop. To move towards a more ecologically valid paradigm, our participants undertook a battery of diverse cognitive tasks designed to challenge different aspects of executive function. The AX-CPT, n-back, mental rotation, and visual search tasks were chosen to challenge response inhibition, working memory, spatial reasoning, and attention. We report results from 45 participants aged 19 to 63 years who completed a two-hour battery comprising four different cognitive tasks. Subjective fatigue ratings and task performance were measured at the beginning and end of the battery. Our novel method resulted in an increase in subjective ratings of fatigue (p < 0.001) and a reduction in task performance (p = 0.008). Future research into mental fatigue may benefit from using this task battery.

What Is Mental Effort: A Clinical Perspective

Although mental effort is a frequently used term, it is poorly defined and understood. Consequently, its usage is frequently loose and potentially misleading. In neuroscience research, the term is used to mean both the cognitive work that is done to meet task demands and the subjective experience of performing that work. We argue that conflating these two meanings hampers progress in understanding cognitive impairments in neuropsychiatric conditions because cognitive work and the subjective experience of it have distinct underlying mechanisms. We suggest that the most coherent and clinically useful perspective on mental effort is that it is a subjective experience. This makes a clear distinction between cognitive impairments that arise from changes in the cognitive apparatus, as in dementia and brain injury, and those that arise from subjective difficulties in carrying out the cognitive work, as in attention-deficit/hyperactivity disorder, depression, and other motivational disorders. We review recent advances in neuroscience research that suggests that the experience of effort has emerged to control task switches so as to minimize costs relative to benefits. We consider how these advances can contribute to our understanding of the experience of increased effort perception in clinical populations. This more specific framing of mental effort will offer a deeper understanding of the mechanisms of cognitive impairments in differing clinical groups and will ultimately facilitate better therapeutic interventions.

A goal-centric outlook on learning

Goals play a central role in human cognition. However, computational theories of learning and decision-making often take goals as given. Here, we review key empirical findings showing that goals shape the representations of inputs, responses, and outcomes, such that setting a goal crucially influences the central aspects of any learning process: states, actions, and rewards. We thus argue that studying goal selection is essential to advance our understanding of learning. By following existing literature in framing goal selection within a hierarchy of decision-making problems, we synthesize important findings on the principles underlying goal value attribution and exploration strategies. Ultimately, we propose that a goal-centric perspective will help develop more complete accounts of learning in both biological and artificial agents.

Automatic or controlled: How does disbelief in free will influence cognitive functioning?

Most people believe in free will. Past research has indicated that reducing this belief has numerous downstream consequences including everyday outcomes as well as neural and cognitive correlates associated with a reduction of self-control. However, the exact mechanisms through which a reduction in free will belief affects self-control are still a matter of investigation. In the present registered report, we used a task switching paradigm to examine whether reducing belief in free will makes people less controlled or whether it enhances their reliance on automatic impulses. Using Bayesian sequential analysis, we failed to conceptually replicate the previous link between free will belief and cognitive control. Our registered report plan mostly accumulated substantial evidence supporting the null hypothesis. That is, diminished belief in free will does neither impact control nor automaticity. Theoretical implications of this finding are discussed.

Information on Averted Infections Increased Perceived Efficacy of Regulations and Intentions to Follow Them

The coronavirus 2019 (COVID-19) pandemic presented policymakers with the need to change people’s behavior in a fundamental way and for an extended period of time. Changing habits is difficult and requires sustained effort, and sustaining effort is especially difficult when it does not seem to yield conspicuous results. The COVID-19 pandemic presented exactly this difficulty, as numbers of infected people continued to rise despite the public’s efforts. In a representative sample from Israel ( N = 600), collected online during the first outbreak of the pandemic, we found that compared to control conditions in which information on only actual infection cases was presented, counterfactual information on the number of averted cases enhances the perceived effectiveness of following the guidelines, which, in turn, enhances perceived importance and intention of doing so (e.g., intention to restrict mobility), but only among those who understood the information. The findings align with self-regulation theories and have practical implications for policymakers.

Inhibition of the supplementary motor area affects distribution of effort over time

In tasks that extend over time, people tend to exert much effort at the beginning and the end, but not in the middle, exhibiting the stuck-in-the-middle pattern (STIM). To date, little is known about the neural mechanisms underlying this effect. As the supplementary motor area (SMA) was previously implicated in coding prospective task-demands, we tested its role in producing the STIM pattern. Participants first underwent an SMA-localization session in which they tapped their fingers repeatedly while fMRI-scanned. In the next two sessions, before playing a 10-min computer game that measured effort-engagement, participants underwent inhibitory 1-Hz repetitive transcranial magnetic stimulation over the SMA, or over a control precuneus location. Three control experiments and a pretest confirmed that this task yields a STIM, which can be eliminated when the task lacks a salient end-point, or is too short. The results of the main experiment showed a more pronounced STIM following inhibitory SMA stimulation compared to control. A control analysis showed that overall level of effort was similar in both conditions, rendering alternative accounts in terms of motor inhibition unlikely. These findings are consistent with the possibility that the SMA may play a role in moment-to-moment coding of effort value, or in related sub-processes, which can cause effort to be distributed more equally over the course of a task.