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.

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.

Working memory updating of emotional stimuli predicts emotional intelligence in females.

Preliminary evidence concerning emotional intelligence (EI) and working memory (WM) showed that the relationship between them is dependent on the emotional content ('hot' or 'cool') of tasks involving WM. In this paper, we continue investigating the relationship between EI and WM, focusing on a crucial function of WM, i.e., the efficacy of updating its content. WM updating shows substantial correlations with general fluid intelligence (gF) and seems to be a significant predictor of cognitive performance and achievement. We assume that if updating is important for a wide range of higher-order processes, updating emotional content in WM could be essential for emotionally intelligent behavior. To test this hypothesis, we constructed two parallel versions of a task that requires WM updating: one with neutral and the other with emotional stimuli. In addition, performance-based measures of both gF and EI were used in the research. Using the structural equation approach, we sought to demonstrate that gF is dependent on the efficiency of WM updating for both emotional and neutral stimuli, whereas EI might depend only on the updating efficacy in the emotional context. The results are discussed in terms of the domain specificity of EI and the domain generality of gF. The main constraint of the study is its limited sample size (n = 123 for intelligence measures, n = 69 for WM updating tasks). Moreover, the study was based on a female sample; thus, the conclusions can be extrapolated only to women.

Professional mathematicians do not differ from others in the symbolic numerical distance and size effects.

The numerical distance effect (it is easier to compare numbers that are further apart) and size effect (for a constant distance, it is easier to compare smaller numbers) characterize symbolic number processing. However, evidence for a relationship between these two basic phenomena and more complex mathematical skills is mixed. Previously this relationship has only been studied in participants with normal or poor mathematical skills, not in mathematicians. Furthermore, the prevalence of these effects at the individual level is not known. Here we compared professional mathematicians, engineers, social scientists, and a reference group using the symbolic magnitude classification task with single-digit Arabic numbers. The groups did not differ with respect to symbolic numerical distance and size effects in either frequentist or Bayesian analyses. Moreover, we looked at their prevalence at the individual level using the bootstrapping method: while a reliable numerical distance effect was present in almost all participants, the prevalence of a reliable numerical size effect was much lower. Again, prevalence did not differ between groups. In summary, the phenomena were neither more pronounced nor more prevalent in mathematicians, suggesting that extremely high mathematical skills neither rely on nor have special consequences for analogue processing of symbolic numerical magnitudes.

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.

More intelligent extraverts are more likely to deceive.

The tendency to lie is a part of personality. But are personality traits the only factors that make some people lie more often than others? We propose that cognitive abilities have equal importance. People with higher cognitive abilities are better, and thus more effective liars. This might reinforce using lies to solve problems. Yet, there is no empirical research that shows this relationship in healthy adults. Here we present three studies in which the participants had free choice about their honesty. We related differences in cognitive abilities and personality to the odds of lying. Results show that personality and intelligence are both important. People low on agreeableness and intelligent extraverts are most likely to lie. This suggests that intelligence might mediate the relationship between personality traits and lying frequency. While personality traits set general behavioral tendencies, intelligence and environment set boundaries.

Working Memory Training for Schoolchildren Improves Working Memory, with No Transfer Effects on Intelligence.

Working memory contributes to many higher-order cognitive processes and predicts general cognitive skills. It is therefore important to know if its functions are trainable. In this study we investigated the malleability of working memory processes in schoolchildren whose cognitive functions are still developing. We also analyzed transfer effects to both general and specific intellectual skills. To address these issues, we examined the effectiveness of working memory training (10 training sessions) in terms of practice effects (trained tasks), near-transfer effects (working memory capacity), and far-transfer effects (psychometric intelligence). Sixty-nine children aged 8-10 participated in the study. The experimental group (42 children) participated in working memory training that intensely engaged the updating function of working memory. The training tasks, implemented as computer games, were based on the n-back and keep track paradigms. There was also an active control group (27 children). The results suggest that the experimental group improved their working memory capacity, as measured with both trained and untrained tasks. Regarding intelligence, far-transfer effects were weak and may be attributed to mere repetition of measurements. Moreover, whereas improvement in the training tasks could be observed after 15 months, the far-transfer effects disappeared in the delayed assessment.

Insightful Imagery is Related to Working Memory Updating.

Available body of evidence concerning the relationship between insight problem solving and working memory (WM) is ambiguous. Several authors propose that restructuring of the problem representation requires controlled search processes, which needs planning and involvement of WM. Other researchers suggest that the restructuring is achieved through the automatic spread of activation in long-term memory, assigning a limited role to WM capacity. In the present study we examined the correlations between insight problem solving performance and measures of WM updating function (n-back task), including general intelligence (as measured by Raven's Advanced Progressive Matrices). The results revealed that updating function shared up to 30% of variance with the insight problem task performance, even when the influence of general mental ability was controlled for. These results suggest that insight problem solving is constrained by individual ability to update the content of WM.

Professional mathematicians differ from controls in their spatial-numerical associations.

While mathematically impaired individuals have been shown to have deficits in all kinds of basic numerical representations, among them spatial-numerical associations, little is known about individuals with exceptionally high math expertise. They might have a more abstract magnitude representation or more flexible spatial associations, so that no automatic left/small and right/large spatial-numerical association is elicited. To pursue this question, we examined the Spatial Numerical Association of Response Codes (SNARC) effect in professional mathematicians which was compared to two control groups: Professionals who use advanced math in their work but are not mathematicians (mostly engineers), and matched controls. Contrarily to both control groups, Mathematicians did not reveal a SNARC effect. The group differences could not be accounted for by differences in mean response speed, response variance or intelligence or a general tendency not to show spatial-numerical associations. We propose that professional mathematicians possess more abstract and/or spatially very flexible numerical representations and therefore do not exhibit or do have a largely reduced default left-to-right spatial-numerical orientation as indexed by the SNARC effect, but we also discuss other possible accounts. We argue that this comparison with professional mathematicians also tells us about the nature of spatial-numerical associations in persons with much less mathematical expertise or knowledge.

Explicit Instructions Increase Cognitive Costs of Deception in Predictable Social Context.

Convincing participants to deceive remains one of the biggest and most important challenges of laboratory-based deception research. The simplest and most prevalent method involves explicitly instructing participants to lie or tell the truth before presenting each task item. The usual finding of such experiments is increased cognitive load associated with deceptive responses, explained by necessity to inhibit default and automatic honest responses. However, explicit instructions are usually coupled with the absence of social context in the experimental task. Context plays a key role in social cognition by activating prior knowledge, which facilitates behaviors consistent with the latter. We hypothesized that in the presence of social context, both honest and deceptive responses can be produced on the basis of prior knowledge, without reliance on truth and without additional cognitive load during deceptive responses. In order to test the hypothesis, we have developed Speed-Dating Task (SDT), which is based on a real-life social event. In SDT, participants respond both honestly and deceptively to questions in order to appear similar to each of the dates. The dates are predictable and represent well-known categories (i.e., atheist or conservative). In one condition participants rely on explicit instructions preceding each question (external cue). In the second condition no explicit instructions are present, so the participants need to adapt based on prior knowledge about the category the dates belong to (internal cue). With internal cues, reaction times (RTs) are similar for both honest and deceptive responses. However, in the presence of external cues (EC), RTs are longer for deceptive than honest responses, suggesting that deceptive responses are associated with increased cognitive load. Compared to internal cues, deception costs were higher when EC were present. However, the effect was limited to the first part of the experiment, only partially confirming our initial hypothesis. The results suggest that the presence of social context in deception tasks might have a significant influence on cognitive processes associated with deception.

The contribution of working memory to fluid reasoning: capacity, control, or both?

Fluid reasoning shares a large part of its variance with working memory capacity (WMC). The literature on working memory (WM) suggests that the capacity of the focus of attention responsible for simultaneous maintenance and integration of information within WM, as well as the effectiveness of executive control exerted over WM, determines individual variation in both WMC and reasoning. In 6 experiments, we used a modified n-back task to test the amount of variance in reasoning that is accounted for by each of these 2 theoretical constructs. The capacity of the focus accounted for up to 62% of variance in fluid reasoning, while the recognition of stimuli encoded outside of the focus was not related to reasoning ability. Executive control, measured as the ability to reject distractors identical to targets but presented in improper contexts, accounted for up to 13% of reasoning variance. Multiple analyses indicated that capacity and control predicted non-overlapping amounts of variance in reasoning.