Work content influences on cognitive task load,emotional state and performance during a simulated 520-days' Mars mission

In high-risk domains such as human space flight, cognitive performances can be negatively affected by emotional responses to events and conditions in their working environment (e.g., isolation and health incidents). The COgnitive Performance and Error (COPE) model distinguishes effects of work content on cognitive task load and emotional state, and their effect on the professional's performance. This paper examines the relationships between these variables for a simulated Mars-mission. Six volunteers (well-educated and -motivated men) were isolated for 520 days in a simulated spacecraft in which they had to execute a (virtual) mission to Mars. As part of this mission, every other week, several computer tasks were performed. These tasks consisted of a negotiation game, a chat-based learning activity and an entertainment game. Before and after these tasks, and after post-task questionnaires, the participants rated their emotional state consisting of arousal, valence and dominance, and their cognitive task load consisting of level of information processing, time occupied and task-set switches. Results revealed significant differences between cognitive task load and emotional state levels when work content varied. Significant regression models were also found that could explain variation in task performance. These findings contribute to the validation of the COPE model and suggest that differences in appraisals for tasks may bring about different emotional states and task performances.     

Human motion coordination: a juggler as an example

This paper introduces a new method for the coordination of human motion based on planning and AI techniques. Motions are considered as black boxes that are activated according to preconditions and produce postconditions in a hybrid, continuous and discrete world. Each part of the body is an autonomous entity that cooperates with the others as determined by global criteria, such as occupation rate and distance to a goal (common to all the entities). With this technique, we can easily specify and solve the motion coordination problem of a juggler that juggles with a dynamic number of balls in real time.     

Knowledge sharing practices as a facilitating factor for improving organizational performance through human capital: A preliminary test

Organizational knowledge sharing, argued to be able to improve organizational performance and achieve competitive advantage, is often not induced successfully. How organizations should encourage and facilitate knowledge sharing to improve organizational performance is still an important research question. This study proposes and examines a model of organizational knowledge sharing that improves organizational performance. Organizational knowledge sharing practices are argued to be able to encourage and facilitate knowledge sharing, and are hypothesized to have a positive relationship with organizational human capital (employee competencies), which is hypothesized to have a positive relationship with organizational performance. Two organizational antecedents (innovation strategy and top management knowledge values) are hypothesized to lead to the implementation of organizational knowledge sharing practices. The hypotheses were examined with data collected from 256 companies in Taiwan. All the hypotheses are supported. This study has both theoretical and practical implications.     

The Alan Welford Memorial Lecture Ageing and human skill: a 40th anniversary

Even 40 years after it was published, a re-reading of Alan Welford's seminal book, Ageing and Human Skill, offers important and curiously neglected ideas. In particular, it shows that current ‘single factor’ models for cognitive ageing, and for general intellectual abilities neglect the complexity of even apparently very simple tasks; that older individuals can be impressively good at acquiring new skills; that the performance of older people on novel tasks is different from that of young adults not only in quantitative terms, because they are slower and less accurate, but also qualitatively, in ways similar to individuals who have suffered damage to the frontal lobes of their brains. We celebrate Alan's prescience in being the first to clearly raise these issues, and to discuss elegant but sadly neglected experimental paradigms and techniques of analysis that allow them to be explored.     

Integral constraints and performance limits on complementary sensitivity: discrete-time systems

We study performance limitation issues for multivariable discrete-time feedback systems. The complementary sensitivity function is employed as a performance measure, and Bode and Poisson-type integral inequalities and -type performance limits are derived. The results exhibit frequency-dependent constraints as well as best achievable limits on the complementary sensitivity function, which are shown to be determined by nonminimum phase zeros, unstable poles, and time delays. In particular, the directions of such zeros and poles are seen to play a central role to this effect.     

Effects of display design on performance in a simulated ship navigation environment

Although automation is playing an increasing role on the ship's bridge, empirical research on the effectiveness of alternative bridge designs is limited. In this paper, we describe an experimental study of the benefits of integrated information display, using a computerized simulation of a highly automated ship's bridge. The study compared three types of interface design, which presented radar and electronic chart information to the operator in different ways: (a) integrated display, (b) functionally-separate display, and (c) spatially-separate display. Effects were examined in relation to time on watch and scenario complexity. Following extensive training on the task, 39 participants were tested over a 4-h experimental session, during which they encountered a sequence of collision scenarios of varying complexity. Using a dual-task methodology, a range of measures of primary and secondary task performance were taken, together with assessment of information sampling behaviour and subjective operator state (workload, fatigue, anxiety and situation awareness). The results indicated slight navigational advantages of the integrated display over the two alternative display types, although it also incurred higher levels of operator cost, particularly fatigue. There were no marked effects of time on watch, but more complex scenarios were associated with impaired performance, increased workload and reduced situation awareness. Overall, the findings have suggested some benefits of integrating primary information sources in a ship's bridge environment. The study further confirms the value of experimental simulations as tools for investigating design issues for ship's bridge automation.     

Work tolerance and physiological responses to thermal environment wearing protective NBC clothing

Abstract

Six young, healthy male subjects performed a series of experiments in a climatic chamber in different environmental conditions wearing protective ventilated NBC clothing. Ambient temperature, TA, ranged from -20 to 35°C, relative humidity, RH, from 20 to 85%, and air velocity, VA, from 0·1 to 5·0 ms^?1. In addition, thermal radiation, measured by the temperature of the globothermometer, TG, was artificially increased in some experiments. A total of 32 experiments were performed. The subject had to exercise on a bicycle ergometer at a mechanical power of 60 W for 120 min. Heart rate, HR, oxygen uptake, VO₂, skin temperature, T_sk and rectal temperature, T_re, were measured during the experiments together with the temperature of the space between skin and garment, T_u. Sweat loss was determined as the difference of the body weight before and after the experiment. T_u was well correlated with the chamber environmental parameters. During heat exposure work duration began to decrease progressively from a T_u 30°C, reducing to 40 min at the highest thermal load. About the same value of T_u, marked the departure of HR, VO₂, T_sk and T_re from the values measured during the same work load in neutral conditions. Also, during cold exposure at -20°C work duration was reduced below 1 h, but the limit appeared to be the cold at the extremities. From these findings it appears that T_u is a good indicator of the thermal load and is related to the environmental condition by the equation: T_u = 9·93 + 0·56 TA + 0·023 TG + 0·14 RH (T in °C, RH in %. For better comfort and performance T_u should be monitored whenever a subject has to work wearing an NBC garment and the ventilating system must be adequate to fulfil the needs imposed on the subject by an adverse environment, in particular a high relative humidity.     

Dynamic clothing insulation. Measurements with a thermal manikin operating under the thermal comfort regulation mode

The main objective of the present work is the assessment of the thermal insulation of clothing ensembles, both in static conditions and considering the effect of body movements. The different equations used to calculate the equivalent thermal resistance of the whole body, namely the serial, the global and the parallel methods, are considered and the results are presented and discussed for the basic, the effective and the total clothing insulations. The results show that the dynamic thermal insulation values are always lower than the corresponding static ones. The highest mean relative difference [(static-dynamic)/static] was obtained with the parallel method and the lowest with the serial. For I_cl the mean relative differences varied from 0.5 to 13.4% with the serial method, from 5.6 to 14.6% with the global and from 7.2 to 17.7% with the parallel method. In addition, the dynamic tests presents the higher mean relative differences between the calculation methods. The results also show that the serial method always presents the higher values and the parallel method the lowest ones. The relative differences between the calculation methods {[(serial-global)/global] and [(parallel-global)/global]} were sometimes significant and associated to the non-uniform distribution of the clothing insulation. In fact, the ensembles with the highest thermal insulation values present the highest differences between the calculation methods.     

Behavioural,physiological and psychological responses of passengers to the thermal environment of boarding a flight in winter

In practice, passengers actively respond to the thermal environment when they board an aircraft in winter, which is not considered in the current standards. In this study, the behavioural, physiological and psychological responses to the thermal environment were examined at 22 °C (with 68 subjects), 20 °C and 26 °C (with 32 subjects). The results showed that the three air temperature levels had significant effect on nozzle usage and clothing adjustment behaviours, surface skin temperature, and thermal sensation vote (TSV). The walking/waiting states prior to boarding the aircraft cabin had a significant effect on the proportion of jacket removal, TSV and thermal comfort vote. After 10 min in the aircraft cabin, the subjects maintained their comfort in a wider range of the thermal environment when the behavioural adjustments existed compared to when they did not. Thus, a suggestion was made for behavioural adjustments to be provided in aircraft cabins.

Practitioner Summary: Experimental investigation of human responses was conducted in an aircraft cabin. Analysis showed that the subjects maintained their comfort in a wider range of the thermal environment when the behavioural adjustments existed compared to when they did not. Thus, a suggestion was made for behavioural adjustments to be provided in aircraft cabins.     

Multimedia and firewalls: a performance perspective

Firewalls are a well-established security mechanism to restrict the traffic exchanged between networks to a certain subset of users and applications. In order to cope with new application types like multimedia, new firewall architectures are necessary. The performance of these new architectures is a critical factor because Quality of Service (QoS) demands of multimedia applications have to be taken into account. We show how the performance of firewall architectures for multimedia applications can be determined. We present a model to describe the performance of multimedia firewall architectures. This model can be used to dimension firewalls for usage with multimedia applications. In addition, we present the results of a lab experiment, used to evaluate the performance of a distributed firewall architecture and to validate the model.     

Display-control compatibility: the relationship between performance and judgments of performance

This study examined whether people can judge the usability of display-control mappings. Participants identified one of two alternatives which were presented in a questionnaire. Several types of stimuli were tested, ranging from simple shapes to semantic stimuli. Choices were found to be predominately correct when usability was defined by an unambiguous spatial relationship between displays and controls. In contrast, estimates were less accurate for items which did not solely rely on spatial congruence. The findings were interpreted in terms of the factors that need to be considered for judgments to be free of error.     

Human reliability analysis and optimization of manufacturing systems through Bayesian networks and human factors experiments: A case study in a flexible intermediate bulk container manufacturing plant

Human reliability analysis (HRA) and optimization in manufacturing systems are effective to reduce system failure. The purpose of this study is to examine the HRA and optimization through a Bayesian network (BN) model and human factors experiments (HFEs). This study was applied to a flexible intermediate bulk container manufacturing plant. The human physiological and psychological factors consisting of personal abilities of flexibility, coordination, memory, and attention were regarded as the only performance shaping factors in this study. With the BN model, the relationship between human factors and human errors was described qualitatively and the impact of the human factor on system failures was judged quantitatively. Then the workers’ abilities training with HFEs based on the fault diagnosis results was carried out. The total numbers of errors have been decreased by 69.06% and the system failure rate has been reduced significantly after training.     

Retention of a standard operating procedure under the influence of social stress and refresher training in a simulated process control task

In a simulated process control task, we investigated the effects of refresher training and acute social stress on performing a standard operating procedure (SOP) containing a production and monitoring task and knowledge recall after a retention interval of two weeks. In a 2?×?2 between-group design (Factor 1: induced social stress, Factor 2: refresher training), 76 engineering students performed an SOP at t1 in week 1 and at t2 in week 3. A MANOVA in week three (t2) indicated a main effect of the refresher training for the SOP execution containing a production and a monitoring task and an impairing effect of stress on the monitoring task. That means that after a retention interval, stress mainly affects the SOP’s monitoring task. An additional correlational analysis showed that knowledge test performance is negatively associated with cortisol level and that retentivity is a strong predictor for knowledge test performance and production task performance, too.

Practitioner Summary: We investigated effects of social stress and refresher training on performing a standard operating procedure (SOP) after a retention interval of two weeks. The impact of social stress reduced the monitoring task performance as part of the SOP, but not the production outcome. Without refresher training, performance is significantly worse.

Abbreviation: SOP: Standard Operating Procedure; MANOVA: Multivariate Analysis of Variance; CSB: Chemical Safety and Hazard Investigation Board; TSST: Trierer Social Stress Test; P-TSST: Placebo Trierer Social Stress Test; WaTrSim: Water Treatment Simulation; HPA axis: hypothalamic pituitary adrenal axis; WIT-2: Wilde Intelligenztest – 2; SPSS: Statistical Package for the Social Sciences; ANOVA: Analysis of Variance.     

Human performance in a multiple-task environment: Effects of automation reliability on visual attention allocation

Diagnostic automation has been posited to alleviate the high demands of multiple-task environments; however, mixed effects have been found pertaining to performance aid success. To better understand these effects, attention allocation must be studied directly. We developed a multiple-task environment to study the effects of automation on visual attention. Participants interacted with a system providing varying levels of automation and automation reliability and then were transferred to a system with no support. Attention allocation was measured by tracking the number of times each task was viewed. We found that participants receiving automation allocated their time according to the task frequency and that tasks that benefited most from automation were most harmed when it was removed. The results suggest that the degree to which automation affects multiple-task performance is dependent on the relative attributes of the tasks involved. Moreover, there is an inverse relationship between support and cost when automation fails.     

Ratings of perceived exertion (RPE) as an index of aerobic endurance during local and general exercises

The main purpose of this study was to assess the correlations of RPE with indicators of endurance (critical power), exhaustion time and the electromyographic activity of a relevant muscle during general and local exercises. Eight healthy subjects participated in the study. During the first session, Maximal Aerobic Power (MAP) was measured by means of an incremental cycling exercise on a Monark ergometer. At 1-week intervals the participants performed a general or local exhausting exercise, which consisted of a cycle exercise (60, 73, 86 or 100% MAP) and a knee extension exercise (lifting a load between 17.5 and 32.5 kg every 3 s), respectively. The critical powers corresponding to cycling (CP_cycling) and knee extension (CP_knee) were calculated from the slope of the linear relationship between exhaustion time (t _lim) and work. Rate of perceived exertion, concerning the whole body (overall RPE [RPE_ov]), RPE concerning the exercising muscles (muscular RPE [RPE_mu]) and exhaustion time were measured. During the last session, the integrated electromyogram of the right Vastus Lateralis (iEMG s^?1) was measured during short (20 s) cycling and knee extension nonexhausting exercises, with the same electrode location, at the different power outputs used during the exhausting exercises. The relationships between RPE_mu at the fifth minute and log t _lim and between iEMG% (percentage of the iEMG s^?1 corresponding to 100% MAP during cycling) and log t _lim were similar for the cycling and knee extension exercises. The mean values of RPE_mu at the fifth minute of exercise calculated for CP_cycling and CP_knee were almost equal (12.3 ± 1.7 versus 12.2 ± 0.9). Similarly, the mean values of iEMG% corresponding to CPcycling and CPknee were equal (78.44 versus 79.02%). These results suggest that RPE_mu is related to aerobic endurance and that the possibility of sustaining a high percentage of maximal aerobic power during a general exercise is mainly related to local muscular factors.