Training visual attention in a naturalistic visual environment

The efficiency of training visual attention in the central and peripheral visual field was investigated by means of a visual detection task that was performed in a naturalistic visual environment including numerous, time-varying visual distractors. We investigated the minimum number of repetitions of the training required to obtain the top performance and whether intra-day training improved performance as efficiently as inter-day training. Additionally, our research aimed to find out whether exposure to a demanding task such as a microsurgical intervention may cancel out the effects of training.

Results showed that performance in visual attention peaked within three (for tasks in the central visual field) to seven (for tasks in the periphery) days subsequent to training. Intra-day training had no significant effect on performance. When attention training was administered after exposure to stress, improvement of attentional performance was more pronounced than when training was completed before the exposure. Our findings support the implementation of training in situ at work for more efficient results.

Practitioner Summary: Visual attention is important in an increasing number of workplaces, such as with surveillance, inspection, or driving. This study shows that it is possible to train visual attention efficiently within three to seven days. Because our study was executed in a naturalistic environment, training results are more likely to reflect the effects in the real workplace.     

An experimental study on individual and group affect in multi-tasking teams

Research has shown that affect can influence human performance in various settings. This study aimed to explore the effects of individual and group affect on task perceptions and performance under different stress conditions (task demand and technology reliability) and team training methods in multi-tasking environments. Seventy-two participants participated in the experiment in two-person teams. The participants’ affect was measured using facial expression recognition technology. Affect aggregated mean and affect similarity were used as indicators of group affect. Self-reports of workload, teamwork satisfaction, trust in team, and trust in technology were collected. The results demonstrated that different stress conditions and training methods altered individual and group affect. Individual affect did not significantly correlate with the task perception measures, while group affect was related to performance in the team-oriented task but not the individual-oriented tasks. These findings suggested that group affect may have an important role in both multi-tasking and team coordination.

Practitioner summary: Affect can influence human performance in various settings. This study explored how affect influences task perceptions and performance for teams in multi-tasking environments. The results demonstrated that individual affect was not correlated with self-reported task perceptions. Group affect was related to team performance in a team-oriented task.     

Effects of backpack weight on the performance of basic short-term/working memory tasks during flat-surface standing

This study empirically investigated the effects of backpack weight on the performance of three basic short-term/working memory (STM/WM) tasks during flat-surface standing. Four levels of backpack weight were considered: 0, 15, 25 and 40% of the body weight. The three STM/WM tasks were the Corsi block, digit span and 3-back tasks, corresponding to the visuo-spatial sketchpad, phonological loop and central executive of WM, respectively. Thirty participants conducted the STM/WM tasks while standing with loaded backpack. Major study findings were that (1) increased backpack weight adversely affected the scores of all three STM/WM tasks; and, (2) the adverse effect of backpack weight was less pronounced for the phonological loop STM task than the other STM/WM tasks. The study findings may help understand and predict the impacts of body-worn equipment weight on the worker’s mental task performance for various work activities requiring simultaneous performance of mental and physical tasks.

Practitioner summary: The current study empirically examined the effects of backpack weight on the performance of three basic STM/WM tasks. The study findings entail that reduces the weight of body-worn equipment can positively impact the worker’s mental task performance in addition to reducing the worker's bodily stresses.

Abbreviations: ACC: anterior cingulate cortex; AP: anterior-posterior; BW: body weight; CoP: centre of pressure; C-S: central executive working memory task and standing; DLPFC: dorsolateral prefrontal cortex; HIP: human information processing; ML: medio-lateral; PMC: premotor cortex; P-S: phonological loop short-term memory task and standing; SMA: supplementary motor area; STM: short-term memory; VLPFC: ventrolateral prefrontal cortex; V-S: visuo-spatial short-term memory task and standing; WM: working memory     

Comparison of visual fatigue caused by head-mounted display for virtual reality and two-dimensional display using objective and subjective evaluation

This study aimed to evaluate objective and subjective visual fatigue experienced before and after performing a visual task while using a head-mounted display for virtual reality (VR-HMD) and two-dimensional (2D) display. Binocular fusion maintenance (BFM) was measured using a binocular open-view Shack–Hartmann wavefront aberrometer equipped with liquid crystal shutters. Twelve healthy subjects performed the BFM test and completed a questionnaire regarding subjective symptoms before and after performing a visual task that induces low visually induced motion sickness (VIMS). BFM (p = .87) and total subjective eye symptom scores (p = .38) were not significantly different between both groups, although these values were significantly lower after the visual task than before the task within both groups (p < .05). These findings suggest that visual fatigue after using a VR-HMD is not significantly different from that after using a 2D display in the presence of low-VIMS VR content.

Practitioner summary: Objective and subjective evaluation of visual fatigue were not significantly different with the use of a head-mounted display for virtual reality (VR-HMD) and two-dimensional display. These results should be valuable not only to engineers developing VR content but also to researchers involved in the evaluation of visual fatigue using VR-HMD.

Abbreviations: VR: virtual reality; VR-HMD: head-mounted display for virtual reality; BFM: binocular fusion maintenance; BWFA: binocular open-view Shack–Hartmann wavefront aberrometer     

Sex differences in upper limb 3D joint contributions during a lifting task

Sex-related differences in work technique may contribute to increasing the risk of musculoskeletal joint disorders among women. In lifting tasks, sex differences have been reported for the trunk and lower limb, although women present a higher prevalence of shoulder disorders. We investigated sex differences in the upper limb technique during a lifting task. Trunk and upper limb kinematics were recorded in 27 women and 27 men lifting a box (6 or 12?kg) from hip to eye level. Work technique was quantified through the three-dimensional contribution of each joint to overall box height. The glenohumeral joint showed a higher contribution in women with a 6?kg box and wrist and elbow joints did with a 12?kg box, compared to men at either 6 or 12?kg. Sex differences occurred systematically above shoulder level. Our results argue for careful consideration of sex during ergonomic intervention, particularly during the overhead task.

Practitioner Summary: We investigated the sex-related differences in upper limb technique during lifting tasks. Results highlight a sex-specific kinematic strategy above the shoulder level on the glenohumeral joint and on the wrist and elbow joints. To help reduce women’s shoulder disorders in overhead task, ergonomic interventions should account for those differences.

Abbreviations: DoF: degree-of-freedom; WR/EL: wrist and elbow; GH: glenohumeral; SC/AC: sternoclavicular and acromioclavicular; TR/PE: pelvo-thoracic     

Functional near-infrared spectroscopy in the evaluation of urban rail transit drivers’ mental workload under simulated driving conditions

The objective of this study is to investigate the potential of functional near-infrared spectroscopy (fNIRS) combined with heart rate variability indices, for the evaluation of the mental workload of urban rail transit drivers under simulated driving conditions, particularly during task engagement and disengagement. Experienced metro drivers wearing fNIRS monitoring systems were asked to drive for 90?min in a professional metro driving simulator. Workload stimulus tasks were added and an n-back task (n?=?3) was implemented to induce workload in the simulated driving experiment. Experimental results indicate that fNIRS are sensitive to mental workload and reliable for discriminating the degree of mental workload. Research findings demonstrate the feasibility and reliability of fNIRS as a tool for real-time evaluating and monitoring driver mental workload along with task factors from a perspective of brain activations during simulated or actual driving.

Practitioner Summary: This study provides evidence for the potential of functional near-infrared spectroscopy (fNIRS) for the evaluation of the mental workload of urban rail transit drivers under simulated driving conditions. The first fNIRS application to mental workload evaluation in the field of urban rail transportation helps companies develop reasonable shiftwork schedule and ensure operation safety.

Abbreviations: fNIRS: functional near-infrared spectroscopy; oxy-Hb: Oxy-hemoglobin; NASA-TLX: National Aeronautics and Space Administration Task Load Index; EEG: electroencephalogram; ECG: electrocardiogram; HRV: variability; LF: low-frequency power; HF: high-frequency power; PFC: prefrontal cortex; NIRS: near-infrared spectroscopy; DWT: discrete wavelet transform; EMG: electromyography; DT: determination test; TP: total power; LF_norm: standardized LF; HF_norm: standardized HF; VLF: very low frequency; deoxy-Hb: deoxy-hemoglobin.     

The stress and workload of virtual reality training: the effects of presence,immersion and flow

The present investigation evaluated the effects of virtual reality (VR) training on the performance, perceived workload and stress response to a live training exercise in a sample of Soldiers. We also examined the relationship between the perceptions of that same VR as measured by engagement, immersion, presence, flow, perceived utility and ease of use with the performance, workload and stress reported on the live training task. To a degree, these latter relationships were moderated by task performance, as measured by binary (Go/No-Go) ratings. Participants who reported positive VR experiences also tended to experience lower stress and lower workload when performing the live version of the task. Thus, VR training regimens may be efficacious for mitigating the stress and workload associated with criterion tasks, thereby reducing the ultimate likelihood of real-world performance failure.

Practitioner Summary: VR provides opportunities for training in artificial worlds comprised of highly realistic features. Our virtual room clearing scenario facilitated the integration of Training and Readiness objectives and satisfied training doctrine obligations in a compelling engaging experience for both novice and experienced trainees.     

Learning rate and subjective mental workload in five truck driving tasks

Both learning curve models and subjective mental workload are useful tools for determining the length of training for new workers and predicting future task performance. An experiment was designed to collect the task completion times and subjective mental workload of five driving tasks including (a) reverse into garage, (b) 3-point turn, (c) parallel parking, (d) S-curve and (e) up-down-hill. The results indicated that task completion times of truck driving can be predicted with a learning curve. Practice significantly reduced the mental workload rating. However, the novice trainees tended to have a more significant reduction because, compared to experienced trainees, they tended to give greater or lower workload scores than the experienced trainees before and after practice, respectively. The current study may not be complete enough to provide guidelines for a training programme, but it is adequate to suggest that learning rate and workload measure can serve as indexes for factoring in the individual differences.

Practitioner summary: Learning curves can be used to determine the length of training for new workers and performance standards for a particular task. Learning rate and mental workload were found to be important measures for comparing individual differences in order to better design a training programme. However, mental workload must be evaluated by experienced participants.     

Evaluating sociotechnical dynamics in a simulated remotely-piloted aircraft system: a layered dynamics approach

As coordination mechanisms change and technology failures occur, a sociotechnical system must reorganise itself across human and technological layers to maintain effectiveness. We present a study examining reorganisation across communication, controls and vehicle layers of a remotely-piloted aircraft system (RPAS) using a layered dynamics approach. Team members (pilot; navigator; photographer) performed 5 simulated RPAS missions using different operator configurations, including all-human and human-autonomy teams. Reorganization (operationally defined using entropy) time series measured the changing system reorganisation profiles under different operator configurations and following autonomy failures. Correlations between these reorganisation profiles and team effectiveness scores describe the manner in which the system had to be coordinated to maintain effectiveness under these changing conditions. Four unplanned autonomy failures were analysed to visualise system reorganisation following a technology failure. With its objective and real-time modelling and measurement capabilities, layered dynamics complements existing systems thinking tools for understanding sociotechnical complexity and enhancing system effectiveness.

Practitioner summary: A layered dynamics approach for understanding how a sociotechnical system dynamically reorganises itself is presented. The layered dynamics of RPAS were analysed under different operator configurations and following autonomy failures. Layered dynamics complements existing system-thinking tools for modelling sociotechnical system complexity and effectiveness.

Abbreviation: RPAS: remotely-piloted aircraft system; HIS: human-systems integration; EAST: event analysis of systemic teamwork; H1: hypothesis 1; H2: hypothesis 2; H3: hypothesis 3; CERTT-STE: cognitive engineering research on team tasks--synthetic task environment; AVO: air vehicle operator; PLO: payload operator; DEMPC: data exploitation, mission planning, and communications; ACT-R: adaptive control of thought-rational; sec: seconds; ANOVA: analysis of variance     

Medium-term effects of a two-desk sit/stand workstation on cognitive performance and workload for healthy people performing sedentary work: a secondary analysis of a randomised controlled trial

Implementing sit/stand workstations in sedentary work environments is a common way to reduce sedentary time, but their medium-term effect on cognitive performance is unclear. To address this circumstance, eighteen office workers participated in a two-arm, randomised controlled cross-over trial (ClinicalTrials.gov Identifier: NCT02825303), either working at a traditional (sit) or an interventional (sit/stand) workplace for 23 weeks. Cognitive performance (working speed, reaction time, concentration performance, accuracy), workload and relevant covariates (salivary cortisol level, heart rate, physical activity, sitting time) were measured pre- and post-intervention under laboratory conditions. MANOVA and RMANOVA results did not show differences in performance parameters and workload, respectively, between sit/stand and traditional workplace users. Differences in text editing accuracy and cortisol levels for sit/stand workstation users indicate potential connectivity to cognitive parameters which should be further examined with large-scale studies. Practitioner summary: Medium-term effects of working at sit/stand workstations on cognitive performance and workload are unexplored. This randomised controlled trial suggests that cognitive performance and workload are unaffected for sit/stand workstation users after 23?weeks of use. However, accuracy appeared to improve and physiological stress appeared to be altered.

Abbreviations: BMI: body mass index; IPAQ: International physical activity questionnaire; MET: metabolic equivalent of task; MANOVA: multivariate ANOVA; NASA TLX: NASA task load index; RMANOVA: repeated measures ANOVA     

Forecasting Ranking in Harness Racing Using Probabilities Induced by Expected Positions

Ranked events are pivotal in many important AI-applications such as Question Answering and recommendations systems. This paper studies ranked events in the setting of harness racing.

For each horse there exists a probability distribution over its possible rankings. In the paper, it is shown that a set of expected positions (and more generally, higher moments) for the horses induces this probability distribution.

The main contribution of the paper is a method, which extracts this induced probability distribution from a set of expected positions. An algorithm is proposed where the extraction of the induced distribution is given by the estimated expectations. MATLAB code is provided for the methodology.

This approach gives freedom to model the horses in many different ways without the restrictions imposed by for instance logistic regression. To illustrate this point, we employ a neural network and ordinary ridge regression.

The method is applied to predicting the distribution of the finishing positions for horses in harness racing. It outperforms both multinomial logistic regression and the market odds.

The ease of use combined with fine results from the suggested approach constitutes a relevant addition to the increasingly important field of ranked events.     

Using a smart textile system for classifying occupational manual material handling tasks: evidence from lab-based simulations

Physical monitoring systems represent potentially powerful assessment devices to detect and describe occupational physical activities. A promising technology for such use is smart textile systems (STSs). Our goal in this exploratory study was to assess the feasibility and accuracy of using two STSs to classify several manual material handling (MMH) tasks. Specifically, commercially-available ‘smart’ socks and a custom ‘smart’ shirt were used individually and in combination. Eleven participants simulated nine separate MMH tasks while wearing the STSs, and task classification accuracy was quantified subsequently using several common models. The shirt and socks, both individually and in combination, could classify the simulated tasks with greater than 97% accuracy. Thus, using STSs appears to have potential utility for discriminating occupational physical tasks in the work environment.

Practitioner summary: A smart textile system could classify diverse MMH tasks with high accuracy. This technology may help in developing future ergonomic exposure assessment systems, with the goal of preventing occupational injuries.     

Introducing ergonomics requirements in the eco-design of energy-related products from users’ behaviour approach

Ergonomics has been a very important activity in the design process. However, ergonomics rarely includes the environmental requirements into the design of products. The article proposes and presents the Eco-Ergo model through its application to a real-world product, a washing machine, to allow designers and ergonomists to establish product design requirements in order to minimise environmental impacts related to user–product interaction during the use stage. This model uses a visual language of representation, Blueprinting-based, that helps designers explore problems they have not previously considered during the market research when a wide variety of products with different interaction elements is analysed. The application of this model allows direct efforts and attention on the user analysis phase in the most influential user’s actions on the environmental performance of energy-related products during use, establishing ergonomics requirements related to users behaviour at the initial design phase.

Practitioner summary: This study provides a proposal to incorporate ergonomics into the practice of eco-design through the use of human factors in the establishment of initial eco-design requirements. This blueprint-based model combines an empirical and theoretical approach, based on the product test developed by designers, ergonomists and environmentalists.

Abbreviations: CO2: carbon dioxide; DBIM: design behaviour intervention model; DfSB: design for sustainable behaviour; DwI Method: design with intent method; LCA: life cycle assessment; LCD: liquid cristal display; MJ: megajoule; MTM: methods-time measurement; PSS: product-service system; RPM: revolutions per minute     

Posture normalisation of 3D body scans

For product developers that design near-body products, virtual mannequins that represent realistic body shapes, are valuable tools. With statistical shape modelling, the variability of such body shapes can be described. Shape variation captured by statistical shape models (SSMs) is often polluted by posture variations, leading to less compact models. In this paper, we propose a framework that has low computational complexity to build a posture invariant SSM, by capturing and correcting the posture of an instance. The posture-normalised SSM is shown to be substantially more compact than the non-posture-normalised SSM.

Practitioner summary: Statistical shape modelling is a technique to map out the variability of (body) shapes. This variability is often polluted by variations in posture. In this paper, we propose a framework to build a posture invariant statistical shape model.

Abbreviations: SSM: statistical shape model; 1D: one-dimensional; 3D: three-dimensional; DHM: digital human model; LBS: linear blend skinning; PCA: princial component analysis; PC: principal component; TTR: thumb tip reach.     

The impact of external facial features on the construction of facial composites

Witnesses may construct a composite face of a perpetrator using a computerised interface. Police practitioners guide witnesses through this unusual process, the goal being to produce an identifiable image. However, any changes a perpetrator makes to their external facial-features may interfere with this process. In Experiment 1, participants constructed a composite using a holistic interface one day after target encoding. Target faces were unaltered, or had altered external-features: (i) changed hair, (ii) external-features removed or (iii) naturally-concealed external-features (hair, ears, face-shape occluded by a hooded top). These manipulations produced composites with more error-prone internal-features: participants’ familiar with a target’s unaltered appearance less often provided a correct name. Experiment 2 applied external-feature alterations to composites of unaltered targets; although whole-face composites contained less error-prone internal-features, identification was impaired. Experiment 3 replicated negative effects of changing target hair on construction and tested a practical solution: selectively concealing hair and eyes improved identification.

Practitioner Summary: The research indicates that when a target identity disguises or changes hair, this can lead to a witness (or victim) constructing a composite that is less readily identified. We assess a practical method to overcome this forensic issue.

Abbreviation: GEE: Generalized Estimating Equations     

Fighter pilots’ heart rate,heart rate variation and performance during instrument approaches

Fighter pilots’ heart rate (HR), heart rate variation (HRV) and performance during instrument approaches were examined. The subjects were required to fly instrument approaches in a high-fidelity simulator under various levels of task demand. The task demand was manipulated by increasing the load on the subjects by reducing the range at which they commenced the approach. HR and the time domain components of HRV were used as measures of pilot mental workload (PMWL). The findings of this study indicate that HR and HRV are sensitive to varying task demands. HR and HRV were able to distinguish the level of PMWL after which the subjects were no longer able to cope with the increasing task demands and their instrument landing system performance fell to a sub-standard level. The major finding was the HR/HRV’s ability to differentiate the sub-standard performance approaches from the high-performance approaches.

Practitioner Summary:

This paper examined if HR and HRV were sensitive to varying task demands in a fighter aviation environment and if these measures were related to variations in pilot’s performance.     

The effect of a passive trunk exoskeleton on metabolic costs during lifting and walking

The objective of this study was to assess how wearing a passive trunk exoskeleton affects metabolic costs, movement strategy and muscle activation during repetitive lifting and walking. We measured energy expenditure, kinematics and muscle activity in 11 healthy men during 5?min of repetitive lifting and 5?min of walking with and without exoskeleton. Wearing the exoskeleton during lifting, metabolic costs decreased as much as 17%. In conjunction, participants tended to move through a smaller range of motion, reducing mechanical work generation. Walking with the exoskeleton, metabolic costs increased up to 17%. Participants walked somewhat slower with shortened steps while abdominal muscle activity slightly increased when wearing the exoskeleton. Wearing an exoskeleton during lifting decreased metabolic costs and hence may reduce the development of fatigue and low back pain risk. During walking metabolic costs increased, stressing the need for a device that allows disengagement of support depending on activities performed.

Practitioner summary: Physiological strain is an important risk factor for low back pain. We observed that an exoskeleton reduced metabolic costs during lifting, but had an opposite effect while walking. Therefore, exoskeletons may be of benefit for lifting by decreasing physiological strain but should allow disengagement of support when switching between tasks.

Abbreviations: COM: centre of mass; EMG: electromyography; LBP: low back pain; MVC: maximum voluntary isometric contraction; NIOSH: National Institute for Occupational Safety and Health; PLAD: personal lift augmentation device; PWS: preferred walking speed without exoskeleton; PWSX: preferred walking speed with exoskeleton; ROM: range of motion; RER: respiratory exchange ratio; V ?O2max: maximum rate of oxygen consumption     

Automation transparency: implications of uncertainty communication for human-automation interaction and interfaces

Operators of highly automated driving systems may exhibit behaviour characteristic for overtrust issues due to an insufficient awareness of automation fallibility. Consequently, situation awareness in critical situations is reduced and safe driving performance following emergency takeovers is impeded. A driving simulator study was used to assess the impact of dynamically communicating system uncertainties on monitoring, trust, workload, takeovers, and physiological responses. The uncertainty information was conveyed visually using a stylised heart beat combined with a numerical display and users were engaged in a visual search task. Multilevel analysis results suggest that uncertainty communication helps operators calibrate their trust and gain situation awareness prior to critical situations, resulting in safer takeovers. In addition, eye tracking data indicate that operators can adjust their gaze behaviour in correspondence with the level of uncertainty. However, conveying uncertainties using a visual display significantly increases operator workload and impedes users in the execution of non-driving related tasks.

Practitioner Summary: This article illustrates how the communication of system uncertainty information helps operators calibrate their trust in automation and, consequently, gain situation awareness. Multilevel analysis results of a driving simulator study affirm the benefits for trust calibration and highlight that operators adjust their behaviour according to multiple uncertainty levels.     

Does skill retention benefit from retentivity and symbolic rehearsal? – two studies with a simulated process control task

Two experiments were designed to compare two symbolic rehearsal refresher interventions (imaginary practice, a hidden introspective process) and investigate the role of retentivity in skill retention. Retentivity is investigated as the ability to memorise and reproduce information and associations that were learned a short time ago. Both experiments comprised initial training (week 1), a symbolic rehearsal for the experimental group (week 2) and a retention assessment (week 3). In the first study, the experimental group received a symbolic rehearsal, while the control group received no rehearsal. In the second study, the experimental group received the same symbolic rehearsal used in study 1, enhanced with rehearsal tasks addressing human–computer interaction. The results showed that both symbolic rehearsal interventions were equally likely to mitigate skill decay. The retentivity showed medium to high correlations with skill retention in both studies, and the results suggest that subjects high in retentivity benefit more from a symbolic rehearsal refresher intervention.

Practitioner Summary: Skill decay becomes a problem in situations in which jobs require the correct mastery of non-routine situations. Two experimental studies with simulated process control tasks showed that symbolic rehearsal and retentivity can significantly mitigate skill decay and that subjects higher in retentivity benefit more from refresher interventions.