Monitoring Cognitive and Emotional Processes Through Pupil and Cardiac Response During Dynamic Versus Logical Task

The paper deals with the links between physiological measurements and cognitive and emotional functioning. As long as the operator is a key agent in charge of complex systems, the definition of metrics able to predict his performance is a great challenge. The measurement of the physiological state is a very promising way but a very acute comprehension is required; in particular few studies compare autonomous nervous system reactivity according to specific cognitive processes during task performance and task related psychological stress is often ignored. We compared physiological parameters recorded on 24 healthy subjects facing two neuropsychological tasks: a dynamic task that require problem solving in a world that continually evolves over time and a logical task representative of cognitive processes performed by operators facing everyday problem solving. Results showed that the mean pupil diameter change was higher during the dynamic task; conversely, the heart rate was more elevated during the logical task. Finally, the systolic blood pressure seemed to be strongly sensitive to psychological stress. A better taking into account of the precise influence of a given cognitive activity and both workload and related task-induced psychological stress during task performance is a promising way to better monitor operators in complex working situations to detect mental overload or pejorative stress factor of error.     

Dissociation of cortisol and behavioral indicators of stress in an orangutan (Pongo pygmaeus) during a computerized task

Computerized testing can induce behavioral signs of frustration in apes. Three variations of a computer task were used to investigate the effects of inter-trial intervals and rate of cursor movement on frustrative behavior and cortisol in an orangutan. Behaviors were recorded during test sessions, and saliva was collected immediately after test sessions for cortisol assay. Behavioral results indicated that extended (20 sec) periods of delay between trials induced signs of frustration in the subject, including forceful manual manipulation of objects and self-scratching. However, cortisol results indicated that Hypothalamic-Pituitary-Adrenal (HPA) axis activity was not induced by task performance. Rather, cortisol levels were reduced during performance of computer tasks compared to baseline levels. Findings from this study suggest that behavioral and cortisol responses to stress induced by performance of computer testing can become dissociated. This study validates salivary cortisol as a measure of HPA activity in apes and demonstrates a normal circadian rhythm of cortisol release in an orangutan.     

Effects of vibration, feed force and exposure duration on operators performing drilling task

It has been shown that vibration level, feed force, and exposure duration cause unfavourable effects on the work performance when hand-held vibrating tools are used by operators. Present study analyzed the effects of these variables on the heart rate and blood pressure of the operators carrying out the drilling task. Under three different levels of vibration (0.3, 0.5, and 1 m/s2), the operators performed the drilling for 3 minutes with three different levels of feed force (100, 200, and 300 N) in study 1, and for three different durations (10, 15, and 20 min) with a feed force of 200 N in study 2. Thirty male subjects participated in the two studies and data were analyzed on the basis of two factor repeated measure kind of experimental design. Results showed that in the kind of drilling task undertaken the level of vibration was statistically significant. However, the main effects of feed force and vibration exposure duration were statistically insignificant. These findings are discussed in the light of previous researches conducted on the subject.     

An analysis of muscular load and performance in using a pen-tablet system

The present paper aims to investigate two characteristics; task performance and muscular load during skill process for the pen-tablet input system with the mouse input system on the PC in order to determine the comprehensive usability for the pen-tablet system. Two computer tasks were designed for the study: task SL and task PT. Task SL was a repetitive computer-drawing including typical mouse motions such as clicking and drag-dropping. Task PT was a polygon tracing task requiring fine-controlled movements with the input device. Surface electromyography (EMG) and performance data were measured during the task. When the pen-tablet was being used, low amplitudes of EMGs for the biceps brachii, the flexor digitorum superficialis, and the extensor digitorum were found, whereas no EMG difference for the trapezius was found for both tasks. On the first day, the performance with the mouse was much higher than the performance with the pen-tablet in terms of error rates and the number of completed trials. However, the performance with the pen-tablet exceeded the performance with the mouse from the second day on, and the subjects performed better with the pen-tablet than with the mouse. Current results imply that the skill process for the pen-tablet system was very short and the subjects felt comfortable to use the new system from the beginning.     

Fatigue effects on tracking performance and muscle activity

It has been suggested that fatigue affects proprioception and consequently movement accuracy, the effects of which may be counteracted by increased muscle activity. To determine the effects of fatigue on tracking performance and muscle activity in the M. extensor carpi radialis (ECR), 11 female participants performed a 2-min tracking task with a computer mouse, before and immediately after a fatiguing wrist extension protocol. Tracking performance was significantly affected by fatigue. Percentage time on target was significantly lower in the first half of the task after the fatigue protocol, but was unaffected in the latter half of the task. Mean distance to target and the standard deviation of the distance to target were both increased after the fatigue protocol. The changed performance was accompanied by higher peak EMG amplitudes in the ECR, whereas the static and the median EMG levels were not affected.

The results of this study showed that subjects changed tracking performance when fatigued in order to meet the task instruction to stay on target. Contrary to our expectations, this did not lead to an overall higher muscle activity, but to a selective increase in peak muscle activity levels of the ECR.     

Automatic Combination of Operators in a Genetic Algorithm to Solve the Traveling Salesman Problem

Genetic algorithms are powerful search methods inspired by Darwinian evolution. To date, they have been applied to the solution of many optimization problems because of the easy use of their properties and their robustness in finding good solutions to difficult problems. The good operation of genetic algorithms is due in part to its two main variation operators, namely, crossover and mutation operators. Typically, in the literature, we find the use of a single crossover and mutation operator. However, there are studies that have shown that using multi-operators produces synergy and that the operators are mutually complementary. Using multi-operators is not a simple task because which operators to use and how to combine them must be determined, which in itself is an optimization problem. In this paper, it is proposed that the task of exploring the different combinations of the crossover and mutation operators can be carried out by evolutionary computing. The crossover and mutation operators used are those typically used for solving the traveling salesman problem. The process of searching for good combinations was effective, yielding appropriate and synergic combinations of the crossover and mutation operators. The numerical results show that the use of the combination of operators obtained by evolutionary computing is better than the use of a single operator and the use of multi-operators combined in the standard way. The results were also better than those of the last operators reported in the literature.     

The Influence of Individual and Team Cognitive Ability on Operators’ Task and Safety Performance: A Multilevel Field Study in Nuclear Power Plants

While much research has investigated the predictors of operators’ performance such as personality, attitudes and motivation in high-risk industries, its cognitive antecedents and boundary conditions have not been fully investigated. Based on a multilevel investigation of 312 nuclear power plant main control room operators from 50 shift teams, the present study investigated how general mental ability (GMA) at both individual and team level can influence task and safety performance. At the individual level, operators’ GMA was predictive of their task and safety performance and this trend became more significant as they accumulated more experience. At the team level, we found team GMA had positive influences on all three performance criteria. However, we also found a “big-fish-little-pond” effect insofar as team GMA had a relatively smaller effect and inhibited the contribution of individual GMA to workers’ extra-role behaviors (safety participation) compared to its clear beneficial influence on in-role behaviors (task performance and safety compliance). The possible mechanisms related to learning and social comparison processes are discussed.     

Flexible ligand docking using evolutionary algorithms: investigating the effects of variation operators and local search hybrids

The docking of ligands to proteins can be formulated as a computational problem where the task is to find the most favorable energetic conformation among the large space of possible protein-ligand complexes. Stochastic search methods such as evolutionary algorithms (EAs) can be used to sample large search spaces effectively and is one of the commonly used methods for flexible ligand docking. During the last decade, several EAs using different variation operators have been introduced, such as the ones provided with the AutoDock program. In this paper we evaluate the performance of different EA settings such as choice of variation operators, population size, and usage of local search. The comparison is performed on a suite of six docking problems previously used to evaluate the performance of search algorithms provided with the AutoDock program package. The results from our investigation confirm that the choice of variation operators has an impact on the search-capabilities of EAs. The introduced DockEA using the best settings found obtained the overall best docking solutions compared to the Lamarckian GA (LGA) provided with AutoDock. Furthermore, the DockEA proved to be more robust than the LGA (in terms of reproducing the results in several runs) on the more difficult problems with a high number of flexible torsion angles.     

Nonstationarity and duration of the R-R-segment in the diagnostics of functional states of operators

The effect of the nonstationarity of R-R interval series on the diagnostics of functional states of operators has been analyzed. The functional states were diagnosed by means of a factor model of heart rate variability. The heart rate was recorded in the supine position, before the performance of an important task, and after its completion. A high resistance of the diagnostics of functional states to nonstationarity was found for all periods. Indices of heart rate variability resistant to nonstationarity were defined. Also, the effect of R-R segment duration on functional states diagnostics was explored. The results obtained allow one to conclude that the diagnostics of functional states based on the three-factor model of heart rate variability can be used on short segments within a range of 256 divided 32 R-R intervals. The indices of the factor model of heart rate variability must be normalized for corresponding R-R segment duration before diagnostics. In addition, the effect of the duration of R-R segment on the indices of heart rate variability was analyzed for different functional states. The indices resistant to the duration of R-R segments and conditions necessary for heart rate recording were defined.     

Cross-modal identification: Effects of contingent changes in the stimulus series

Two computer controlled experiments in an olfactory cross-modal matching task, using two-component odour mixtures matched against bar diagrams, were designed so that stimulus presentation was contingent upon the recent performance of the subject; stimuli that were relatively poorly (in experiment 1) or well (in experiment 2) matched were more frequently presented. Analysis shows that the autoregressive structure of the performance is modified by such contingent presentation and that there is a weak relationship between transmitted information in matching and the time series structure of the matching errors. It is suggested that the process is nonlinear.     

Features of learning voluntary control of posture after pyramidal and nigrostriatal lesions

The study was aimed at investigation of a deficit of learning the center-of-pressure voluntary control in patients with lesions of corticospinal and nigrostriatal systems. Thirty three patients with Parkinson's disease and 20 patients with hemiparesis after cerebrovascular accidents in the MCA participated in the investigation. The subjects stood on a force platform and in the form of a computer game were trained to match the projection of the center of pressure (a cursor) with a target on the screen under the visual feedback control. Two different postural tasks were presented. In the first task the direction of the center-of-pressure shift was not known before, so the subject learned the general strategy of the center-pressure control. In the other task a precise postural coordination should be formed. The voluntary control of the center-of-pressure position was found to be impaired in both groups of patients. In the task of moving the center of pressure in various directions (general strategy), no differences in the initial deficit of the task performance were found between the groups, but the learning was more efficient in the group of hemiparetic patients. However, in the task with precise postural coordination, despite the greater initial deficit in the parkinsonian patients, the learning in this group of patients was substantially more efficient than in hemiparetic patients. The results suggest both common and different features of the involvement of the corticospinal and nigrostriatal systems in learning voluntary control of posture.     

The Sense of Agency during Continuous Action: Performance Is More Important than Action-Feedback Association

The sense of agency refers to the feeling that one is controlling events through one’s own behavior. This study examined how task performance and the delay of events influence one’s sense of agency during continuous action accompanied by a goal. The participants were instructed to direct a moving dot into a square as quickly as possible by pressing the left and right keys on a keyboard to control the direction in which the dot traveled. The interval between the key press and response of the dot (i.e., direction change) was manipulated to vary task difficulty. Moreover, in the assisted condition, the computer ignored participants’ erroneous commands, resulting in improved task performance but a weaker association between the participants’ commands and actual movements of the dot relative to the condition in which all of the participants’ commands were executed (i.e., self-control condition). The results showed that participants’ sense of agency increased with better performance in the assisted condition relative to the self-control condition, even though a large proportion of their commands were not executed. We concluded that, when the action-feedback association was uncertain, cognitive inference was more dominant relative to the process of comparing predicted and perceived information in the judgment of agency.     

Division of labour and social insect colony performance in relation to task and mating number under two alternative response threshold models

Some social insects exhibit an exceptionally high degree of polyandry. Alternative hypotheses exist to explain the benefits of multiple mating through enhanced colony performance. This study critically extends theoretical analyses of the hypothesis that enhanced division of labour confers fitness benefits to the queen that are sufficient to explain the observed mating frequencies of social insects. The effects of widely varying numbers of tasks and matings were systematically investigated in two alternative computer simulation models. One model was based on tasks that have to be performed to maintain an optimal trait value, while the other model was based on tasks that only have to be sufficiently performed to exceed a minimum trait value to confer full fitness returns. Both model versions were evaluated assuming a broad and a narrow response threshold distribution. The results consistently suggest a beneficial effect of multiple mating on colony performance, albeit with quickly diminishing returns. An increasing number of tasks decreased performance of colonies with few patrilines but not of more genetically diverse colonies. Instead, a performance maximum was found for intermediate task numbers. The results from the two model versions and two response threshold distributions did not fundamentally differ, suggesting that the type of tasks and the breadth of response thresholds do not affect the benefit of multiple mating. In general, our results corroborate previous models that have evaluated simpler task/patriline scenarios. Furthermore, selection for an intermediate number of tasks is indicated that could constrain the degree of division of labour. We conclude that enhanced division of labour may have favoured the evolution of multiple mating but is insufficient to explain the extreme mating numbers observed in some social insects, even in complex task scenarios.     

A decision-making approach to the operation of flexible manufacturing systems

This paper introduces a generic decision-making framework for assigning resources of a manufacturing system to production tasks. Resources are broadly defined production units, such as machines, human operators, or material handling vehicles; and tasks are activities performed by resources. In the specific context of FMS, resources correspond to individual machines; tasks correspond to operations to be performed on parts. The framework assumes a hierarchical structure of the system and calls for the execution of four consecutive steps to make a decision for the assignment of a resource to a task. These steps are 1) establishment of decision-making criteria, 2) formation of alternative assignments, 3) estimation of the consequences of the assignments, and 4) selection of the best alternative assignment. This framework has been applied to an existing FMS as an operational policy that decides what task will be executed on which resource of this FMS. Simulation runs provide some initial results of the application of this policy. It is shown that the policy provides flexibility in terms of system performance and computational effort.     

Influence of VDT monitor positions on discomfort and performance of users with or without bifocal lenses

The difficulty of video display terminal users with bifocal lenses through a traditional workstation increases the complaints and risks for upper extremity cumulative trauma disorders. Furthermore, the regular and no lens users also have problems with traditionally designed workstations over prolonged periods of video display terminal use. A study was conducted on 14 subjects to investigate the effect of computer monitor location for video display terminal users with or without bifocals on subjective assessment and performance. The two monitor locations were 15 degrees and 40 degrees below horizontal eye level. The experimental task consisted of reading words from computer screens and typing them from the reverse side to the next column. Each experimental session lasted one hour. Males with bifocal lenses had less discomfort in the neck, shoulders, forearms, and wrists, less tiredness and eyestrain and higher performance with a 40 degrees angle monitor than with a 15 degrees angle monitor. A similar conclusion has been reached for females. Users with bifocal lenses had significantly higher neck discomfort and lower performance than nonbifocal users. The 40 degrees angle monitor caused less neck discomfort than the 15 degrees angle monitor did. Overall, females had less physical discomfort, less tiredness, and higher performance than males.     

A cross-sectional study of the relation between symptoms and physical findings in computer operators

Background  

The character of upper limb disorder in computer operators is subject to debate. A peripheral nerve-involvement is suggested from the common presence of a triad of symptoms consisting of pain, paraestesiae and subjective weakness, and from physical findings suggesting neuropathy. This study aimed to examine the outcome of a detailed neurological examination in computer operators and to compare findings with the presence of symptoms.     

Role of the right brain hemisphere in training for the operator work

Functional state of the human right brain hemisphere was studied during simulation of 4-hour operator's training work with a computer in novel conditions. Participants of the experiments differed in the degree of extraversion and baseline level of cortical activity. The obtained results suggest that the role of the right hemisphere in the process of simulated activity consists in reception and primary processing of information. This hemisphere is not involved in the correction of cortical activation to the optimal level of activity, which is necessary for the efficient performance of a task.     

The Effect of a Stroop-like Task on Postural Control in Dyslexic Children

The influence of a secondary task on concurrent postural control was explored in twenty-one dyslexic children (mean age: 10.4±0.3 years). Data were compared with twenty age-matched non-dyslexic children. As a secondary task, a modified Stroop test was used, in which words were replaced with pictures of fruits. The postural control of children was recorded in standard Romberg condition as the children were asked to name the colour of fruits appearing consecutively on a computer screen. Two conditions were tested: a congruent condition, in which the fruit was drawn in its natural ripe colour, and a non-congruent colour condition (NC), in which the fruit was drawn in three abnormal colours. A fixating condition was used as baseline. We analyzed the surface, length and mean speed of the center of pressure and measured the number of correct responses in the Stroop-like tasks. Dyslexic children were seen to be significantly more unstable than non-dyslexic ones. For both groups of children, the secondary task significantly increased postural instability in comparison with the fixating condition. The number of correct responses in the modified Stroop task was significantly higher in the non-dyslexic than in the dyslexic group. The postural instability observed in dyslexic children is in line with the cerebellar hypothesis and supports the idea of a deficit in automatic performance in such children. Furthermore, in accordance with cross domain competition model, our findings show that attentional resources are used to a greater extent by the secondary task than in controlling body stability.     

Exploring the Impact of Target Eccentricity and Task Difficulty on Covert Visual Spatial Attention and Its Implications for Brain Computer Interfacing

Objective

Covert visual spatial attention is a relatively new task used in brain computer interfaces (BCIs) and little is known about the characteristics which may affect performance in BCI tasks. We investigated whether eccentricity and task difficulty affect alpha lateralization and BCI performance.

Approach

We conducted a magnetoencephalography study with 14 participants who performed a covert orientation discrimination task at an easy or difficult stimulus contrast at either a near (3.5°) or far (7°) eccentricity. Task difficulty was manipulated block wise and subjects were aware of the difficulty level of each block.

Main Results

Grand average analyses revealed a significantly larger hemispheric lateralization of posterior alpha power in the difficult condition than in the easy condition, while surprisingly no difference was found for eccentricity. The difference between task difficulty levels was significant in the interval between 1.85 s and 2.25 s after cue onset and originated from a stronger decrease in the contralateral hemisphere. No significant effect of eccentricity was found. Additionally, single-trial classification analysis revealed a higher classification rate in the difficult (65.9%) than in the easy task condition (61.1%). No effect of eccentricity was found in classification rate.

Significance

Our results indicate that manipulating the difficulty of a task gives rise to variations in alpha lateralization and that using a more difficult task improves covert visual spatial attention BCI performance. The variations in the alpha lateralization could be caused by different factors such as an increased mental effort or a higher visual attentional demand. Further research is necessary to discriminate between them. We did not discover any effect of eccentricity in contrast to results of previous research.     

Effects of spatial-imagery task performance on the heart rate variability

Effects of the efficiency of spatial task performance on the autonomic heart control were studied. Dynamic changes in autonomic balance diagnosed on the heart rate variability during maze-model task performance (the type of spatial-imagery activity) showed that the type of heart rate regulation depended on the performance efficiency. The results suggest that in subjects with low performance efficiency, problems in performance are associated with negative emotions that produce the emotional psychogenic stress. In subjects with high efficiency, the autonomic contour of the heart rate regulation prevailed. This was presumable associated with the adequacy of the maze-model task.