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.

Multiple Reprocessing of Conductive PLA 3D-Printing Filament: Rheology, Morphology, Thermal and Electrochemical Properties Assessment

Additive manufacturing technologies are gaining more and more attention, resulting in the development or modification of 3D printing techniques and dedicated materials. On the other hand, economic and ecological aspects force the industry to develop material recycling strategies. In this work, the multiple reprocessing of a commercially available PLA conductive composite with carbon black filler, dedicated to 3D printing, was investigated. The effects of extrusion temperature (190 °C and 200 °C) and reprocessing steps (1-5 steps) on the rheology, morphology, thermal and electrochemical properties of the conductive PLA 3D-printing filament were evaluated. The results showed deterioration of the thermal stability and material strength, as well as the influence of reprocessing on the melting point, which increases after initial melting. The electronic conduction mechanism of the composite depends on the percolation paths and it is also affected by the multiple processing. The reversibility of the [Fe(CN)₆]^3-/4- redox process diminishes with a higher degradation level of the conductive PLA. Importantly, the material fluidity was too high after the multiple reprocessing, which should be considered and suitably corrected during CB-PLA application as a 3D-printed electrode material.

Says Who? Credibility Effects in Self-Verification Strivings

Research shows that people prefer self-consistent over self-discrepant feedback-the self-verification effect. It is not clear, however, whether the effect stems from striving for self-verification or from the preference for subjectively accurate information. We argue that people prefer self-verifying feedback because they find it to be more accurate than self-discrepant feedback. We thus experimentally manipulated feedback credibility by providing information on its source: a student (control condition) or an experienced psychologist (experimental condition). In line with our expectations, the results of two preregistered studies with 342 adults showed that people preferred self-verifying feedback only in the control condition. In the experimental condition, the effect disappeared (or reversed, in Study 1). Study 2 showed that individual differences in credibility (epistemic authority) ascribed to the self and to psychologists matter as well. These findings suggest that feedback credibility, rather than the desire for self-verification, often drives the self-verification effect.

The level of sexual satisfaction and life satisfaction during second the wave of the COVID-19 pandemic in Poland

INTRODUCTION

The COVID-19 pandemic has unquestionably changed the lives of Polish people, creating anxiety and uncertainty. Life satisfaction and sexual satisfaction are subjective evaluations of life and the sexual sphere. Previous research indicates a relationship between sexual satisfaction and life satisfaction.

AIM

The purpose of this study is to demonstrate what level of sexual satisfaction was present during the second wave of the COVID-19 pandemic, taking into account gender, sexual orientation, and relational status, and to examine the relationship between sexual satisfaction and life satisfaction.

MATERIAL AND METHODS

There were 440 participants, aged between 18 and 40 (M = 24.31, SD = 4.90). The study was conducted online. The Sexual Satisfaction Questionnaire developed by Dolińskia-Zygmunt and Nomejko was used to measure sexual satisfaction, while the Satisfaction with Life Scale developed by Diner et al. was used to measure subjective aspect of life satisfaction.

RESULTS

Most of the respondents are satisfied with their life (33%) and sexual sphere (42%). Relationship status is important for the sense of both sexual and life satisfaction, while gender and sexual identity were not associated with any other variable. There is a positive correlation between life satisfaction and sexual satisfaction (r = 0.438, p <0.001). Regression analysis showed that significant predictors of life satisfaction are: sexual satisfaction (p <0.001) and relationship status. (p <0.001).

CONCLUSIONS

During the COVID-19 pandemic, respondents self-rated their life satisfaction and sexual satisfaction highly, although being single can lower both types of satisfaction.

The Effects of Working Memory Training on Brain Activity

This study aimed to investigate if two weeks of working memory (WM) training on a progressive N-back task can generate changes in the activity of the underlying WM neural network. Forty-six healthy volunteers (23 training and 23 controls) were asked to perform the N-back task during three fMRI scanning sessions: (1) before training, (2) after the half of training sessions, and (3) at the end. Between the scanning sessions, the experimental group underwent a 10-session training of working memory with the use of an adaptive version of the N-back task, while the control group did not train anything. The N-back task in the scanning sessions was relatively easy (n = 2) in order to ensure high accuracy and a lack of between-group differences at the behavioral level. Such training-induced differences in neural efficiency were expected. Behavioral analyses revealed improved performance of both groups on the N-back task. However, these improvements resulted from the test-retest effect, not the training outside scanner. Performance on the non-trained stop-signal task did not demonstrate any transfer effect. Imaging analysis showed changes in activation in several significant clusters, with overlapping regions of interest in the frontal and parietal lobes. However, patterns of between-session changes of activation did not show any effect of training. The only finding that can be linked with training consists in strengthening the correlation between task performance accuracy and activation of the parietal regions of the neural network subserving working memory (left superior parietal lobule and right supramarginal gyrus posterior). These results suggest that the effects of WM training consist in learning that, in order to ensure high accuracy in the criterion task, activation of the parietal regions implicated in working memory updating must rise.

The (In)significance of Executive Functions for the Trait of Self-Control: A Psychometric Study

Self-control (SC) is an individual trait defined as the ability to pursue long-distance goals in spite of the obstacles generated by current desires, innate or learned automatisms, and physiological needs of an organism. This trait is relatively stable across the life span and it predicts such important features as level of income, quality of social relationships, and proneness to addictions. It is widely believed that the cognitive substrate of SC involves the executive functions (EFs), such as inhibitory control, shifting of attention, and working memory updating. However, the empirical evidence concerning the relationships between trait SC and EFs is not convincing. The present study aims to address two questions: (1) what is the strength of relationships between trait SC and EFs, and (2) which aspects of SC are predicted by particular EFs, if at all. In order to answer these questions, we carried out a psychometric study with 296 participants (133 men and 163 women, mean age 23.31, SD 3.64), whom we investigated with three types of tools: (1) a battery SC scales and inventories, (2) a battery of EFs tasks, and (3) two general intelligence tests. Structural equation modeling approach was used to analyze the data. We found that the latent variables representing SC and the latent variable representing EFs did not show any relationship. The standardized path coefficient between EFs and general intelligence turned out rather strong. We conclude that the trait of SC, measured with questionnaires, does not depend on the strength of cognitive control, measured with EFs tasks.

Effect of selected antioxidants in beta-cyfluthrin-induced oxidative stress in human erythrocytes in vitro

beta-Cyfluthrin is one of the most widely used type II pyrethroid in agriculture. The aim of this study was to examine (1) the possibility of beta-cyfluthrin to induce oxidative stress in human erythrocytes in vitro and its effect on catalase (CAT) and superoxide dismutase (SOD) activities as well as (2) the role of melatonin (MEL; 2mM), its precursor--N-acetylserotonin (NAS; 1mM), quercetin (Q; 80 microM) and rutin (R; 80 microM) in alleviating the cytotoxic effects of beta-cyfluthrin. Erythrocytes were divided into portions. The first portion was incubated for 4h at 37 degrees C with different concentrations (0, 43, 215, 1075 ppm) of beta-cyfluthrin. The other portions were preincubated with selected antioxidant, respectively for 30 min and followed by beta-cyfluthrin incubation for 4h. Malondialdehyde (MDA) concentrations, CAT and SOD activities, as well as haemolysis percentage (H) were measured in all treatment portions of erythrocytes. It could be concluded that the in vitro toxicity of beta-cyfluthrin may be associated with oxidative stress. Significant reduction in the activities of CAT was observed at all beta-cyfluthrin concentrations, while SOD activities were significantly decreased only in erythrocytes incubated with the highest beta-cyfluthrin concentration. SOD activity of the non-pretreated erythrocytes exposed to the lowest dose of beta-cyfluthrin was significantly greater when compared to comparably beta-cyfluthrin-exposed antioxidant pretreated cells. The highest concentration of beta-cyfluthrin has caused over 35% haemolysis, and the lowest concentration about 15%. MEL pretreatment had no effect on H and MDA induction by beta-cyfluthrin. NAS, Q and R reduced H and MDA level, but could not prevent induction of these parameters. Compared to other antioxidants NAS appeared to maintain better the CAT activity at control levels for all doses of beta-cyfluthrin. Pretreatment with Q was found to protect against the decrease in SOD activity induced by beta-cyfluthrin.