Theoretical issues in physical ergonomics

There is a seemingly perennial debate in the literature about the relative merits of using a secondary task as a measure of spare attentional capacity. One of the main drawbacks is that it could adversely affect the primary task, or other measures of mental workload. The present experiment therefore addressed an important methodological issue for the dual-task experimental approach–that of secondary task interference. The current experiment recorded data in both single- and dual-task scenarios to ascertain the level of secondary task interference in the Southampton Driving Simulator. The results indicated that a spatial secondary task did not have a detrimental effect on driving performance, although it consistently inflated subjective mental workload ratings. However, the latter effect was so consistent across all conditions that it was not considered to pose a problem. General issues of experimental design, as well as wider implications of the findings for multiple resources theory, are discussed.     

Automation cueing modulates cerebral blood flow and vigilance in a simulated air traffic control task

Automation cueing of impending hazards or critical signals can have both beneficial and deleterious effects on the human operator, depending on automation reliability. To assess these effects, transcranial Doppler sonography (TCD), a low-cost non-invasive procedure that allows continuous monitoring of blood flow in the left and right cerebral hemispheres, was used to examine the influence of automation cues of varying reliability on vigilance performance in a 40-min simulated air traffic control task. Four levels of automation cue reliability (100, 80 and 40% reliable cueing and a no-cue control) were combined factorially with two levels of critical signal salience (high and low). For both levels of signal salience, the detection rate of critical signals was very high and remained stable over time with 100% cue-reliability, but declined over time in the remaining cue conditions, so that, by the end of the task, performance efficiency was best in the 100% condition followed in order by the 80%, 40%, and no-cue conditions. These performance effects for cueing were very closely mirrored by changes in cerebral blood flow in the right (but not the left) hemisphere in conjunction with low salience signals. The results fit well with an attentional resource model of vigilance and show that cerebral blood flow provides a metabolic index of the utilization of information-processing resources during sustained attention. The demonstration of systematic modulation of cerebral blood flow with time on task, automation cueing and signal salience also provides strong evidence for a right hemispheric brain system that is involved in the functional control of vigilance performance over time. Measurement of the activation of this system, as a reflection of operator mental workload, can, therefore, inform the design of optimal automation cueing.     

Engaging the human operator: a review of the theoretical support for the vigilance decrement and a discussion of practical applications

Abstract

Vigilance, or the ability to sustain attention for extended periods of time, has been of interest to the human factors and ergonomics community for 70 years. During this time, several theories have attempted to account for the performance effects commonly associated with vigilance (i.e. the decrement, which manifests in fewer correct detections and longer response times to targets over time). We provide a cohesive review of the current empirical support for the three major theories explaining the vigilance decrement and describe the limitations of each theory herein. The three overarching theories of vigilance performance and the vigilance decrement include: cognitive resource theory, mindlessness theory and mind-wandering theory. Importantly, each of these theories relies on unique definitions of task engagement to understand operator overload or underload. The differences in the operationalisation of task engagement are problematic in the application of vigilance research to the real world. In this article, we describe the utility of a unified definition of task engagement and demonstrate how resource theory is better poised to account for cognitive task engagement than physical task engagement, which is emphasised in other theories.     

Neuroergonomics: Opportunities and challenges of merging cognitive neuroscience with cognitive ergonomics

As with any merger of previously unrelated scientific disciplines, the usefulness of combining cognitive neuroscience and cognitive ergonomics to create the new field of 'neuroergonomics' depends on the significance of the research subjects that could not be addressed if the two fields remained separated. Situations characterized by a scarcity of overt operator behaviour and performance represent one driving force for combining the two fields. In those situations, neurobiological indices of cognitive processes and capacities may emerge as the main, or even exclusive, source of information about the operator's cognitive status and activities. This information is needed, for example, to support adaptive aiding and dynamic function allocation in the context of human-automation cooperation. The utilization of research approaches and measurements more typical of cognitive neuroscience will benefit the field of cognitive ergonomics to the extent that multidimensional psychological constructs (such as situation awareness and mental workload) are reduced to their underlying cognitive operations which are more isomorphic with activity changes in brain regions, circuits and distributed neuronal systems. The transformation of these constructs and paradigms will, in turn, enable cognitive ergonomics to contribute to progress in the field of cognitive neuroscience.     

Consideration of several mental workload categories: perspectives for elaboration of new ergonomic recommendations concerning shiftwork

In this article, a reflection is presented concerning consideration of several mental workloads in ergonomics to describe work situation. For that, results of three experiments are recalled and put into perspective to understand relationships between mental workload and performance, and between different measures of mental workload. A integrative model IWA for individual – mental workload – activity is presented to explain interactions between task parameters, individual characteristics and contextual characteristics showing relevance to consider all the elements of a work situation to can estimate the more correctly possible mental workload supported by operator. Then, discussion on relevance of mental workload measures permits to highlight the lack of exhaustive measures of different components of mental workload. Finally, methodological propositions with a diagnostic or prognostic approach are presented in order to consider all elements described in model IWA.     

A proposed psychological model of driving automation

This paper considers psychological variables pertinent to driver automation. It is anticipated that driving with automated systems is likely to have a major impact on the drivers and a multiplicity of factors needs to be taken into account. A systems analysis of the driver, vehicle and automation served as the basis for eliciting psychological factors. The main variables to be considered were: feed-back, locus of control, mental workload, driver stress, situational awareness and mental representations. It is expected that anticipating the effects on the driver brought about by vehicle automation could lead to improved design strategies. Based on research evidence in the literature, the psychological factors were assembled into a model for further investigation.     

Commentary

Mental workload measurement has been an important issue in human factors/ergonomics efforts over the last half century. Recent advances in technological capabilities, analytical techniques and the increasing availability of equipment for non-invasive, real-time assessment of human brain function have led to revolutionary advances in mental workload measurement. Research from several laboratories brought together in this special issue document the feasibility and potential application of these advances for enhancing human performance and safety in a variety of work and leisure environments. Measures of brain function have several advantages over alternative measurement techniques, so long as they are used appropriately and their limitations are understood. These advantages include increased sensitivity to both transient and continuous fluctuations in mental demand without the need to introduce an additional task as well as the ability to discern the relative contributions of various brain mechanisms as a result of task dynamics. Neurophysiological measures offer several advantages and, used in conjunction with behavioural indices, are providing converging and, in some cases, diverging evidence that enable the refinement of theoretical models of longstanding historical significance to the field of ergonomics.     

How to keep drivers engaged while supervising driving automation? A literature survey and categorisation of six solution areas

Abstract

This work aimed to organise recommendations for keeping people engaged during human supervision of driving automation, encouraging a safe and acceptable introduction of automated driving systems. First, heuristic knowledge of human factors, ergonomics, and psychological theory was used to propose solution areas to human supervisory control problems of sustained attention. Driving and non-driving research examples were drawn to substantiate the solution areas. Automotive manufacturers might (1) avoid this supervisory role altogether, (2) reduce it in objective ways or (3) alter its subjective experiences, (4) utilize conditioning learning principles such as with gamification and/or selection/training techniques, (5) support internal driver cognitive processes and mental models and/or (6) leverage externally situated information regarding relations between the driver, the driving task, and the driving environment. Second, a cross-domain literature survey of influential human-automation interaction research was conducted for how to keep engagement/attention in supervisory control. The solution areas (via numeric theme codes) were found to be reliably applied from independent rater categorisations of research recommendations. Areas (5) and (6) were addressed by around 70% or more of the studies, areas (2) and (4) in around 50% of the studies, and areas (3) and (1) in less than around 20% and 5%, respectively. The present contribution offers a guiding organisational framework towards improving human attention while supervising driving automation.     

The benefits of imperfect diagnostic automation: a synthesis of the literature

This review of the literature examines, in a quantitative fashion, how the level of imperfection or unreliability of diagnostic automation affects the performance of the human operator who is jointly consulting that automation and the raw data itself. The data from 20 different studies were used to generate 35 different data points that compared performance with varying levels of unreliability, with that of a non-automated baseline condition. A regression analysis of benefits/costs relative to baseline was carried out, and revealed a strong linear function of benefits with reliability. The analysis revealed that a reliability of 0.70 was the ‘crossover point’ below which unreliable automation was worse than no automation at all. The analysis also revealed that performance was more strongly affected by reliability in high workload conditions, implicating the role of workload-imposed automation dependence in producing this relationship, and suggesting that humans tend to protect performance of concurrent tasks from imperfection of diagnostic automation.     

On the theory of fuzzy signal detection: Theoretical and practical considerations

This work examines the foundations for and explores the implications of fuzzy signal detection (Fuzzy SDT), a theory that represents the marriage of two powerful extant theories, fuzzy set theory and signal detection theory. Fuzzy SDT permits the modelling and prediction of human, machine, and human-machine performance in a wide range of settings. Fuzzy SDT exploits the strengths of each theory to provide new and dynamic insights into performance. Fuzzy SDT explicitly recognizes that the binary decision states of classic signal detection represent two ends of a single continuum whose uncertainty decreases towards such end states and is maximized in its centre. It is shown how Fuzzy SDT has its origins in some more general concepts of human performance, and companion works are referenced which provide the mathematical foundation for Fuzzy SDT and its application in a specific domain. The present work examines the wider implications of Fuzzy SDT by illustrating the relevance of fuzzification in the larger cycle of design, configuration, and use of technology. It also examines the broader concerns of the temporal relationship between signal and response, showing time to be a crucial, if neglected, dimension of action, the exploration and exploitation of which can produce a deeper understanding of human behaviour in psychology, machine behaviour in engineering and human-machine behaviour in ergonomics.     

Towards ecological validity of research in cognitive ergonomics

Psychology is one of the main disciplines that have been implied in the development of cognitive ergonomics. For a long time, at least from the 1960s, some researchers in psychology have contributed to research in cognitive ergonomics with the aim of elaborating basic psychological knowledge, (a) with high ecological validity, and (b) with clear relevance to application. This paper stresses the value of this perspective for psychology as well as cognitive ergonomics, and evaluates the results of such an enterprise. Ecological validity is considered as a particular aspect of external validity that enables researchers to transfer findings from experimental situations ('artificial' ones or designed for research purpose) to real work situations ('natural' (obviously, in this context 'natural' includes 'cultural') ones or imposed by comprehension needs). This aspect is discussed as regards classical distinctions like basic/applied research and research/practice. Attention is particularly devoted to the necessary (ecological) context needed by expert operators to implement their work expertise, which is the target of the comprehension aim of cognitive ergonomics. Conclusions are drawn in terms of methods to design and evaluate ecological validity, not only to understand cognitive mechanisms, but also to improve cognitive work conditions and the overall performance of human-machine systems.     

A brain-based system for adaptive automation

Adaptive automation refers to technology that can change its mode of operation dynamically. Further, both the technology and the operator can initiate changes in the level or mode of automation. One of the important issues surrounding this technology concerns the method for initiating changes in the state of automation. The present paper considers the potential of using brain activity to drive an adaptive automation system. Relevant research on EEG is presented followed by a review of several experiments in which EEG is used to trigger changes among system modes in an adaptive automation system. The system moderates operator task load based upon an index derived from a ratio of EEG power bands. The research shows that it may be feasible to build an adaptive automation system and use this index of brain activity to drive the system. The paper concludes with a discussion of several issues that still need to be addressed before this approach can move beyond the laboratory.     

Providing practitioners with techniques for cognitive work analysis

Contributing to the advancement of cognitive ergonomics, both as a scientific discipline and as a field of professional activity, is a major challenge for the future of ergonomics. It is to advance this objective that I want to make my contribution: while cognitive ergonomics has undoubtedly become established as a scientific discipline, it is still only applied in an approximate fashion by consultant ergonomists in their day-to-day work of analysing and improving socio-technical systems. The cognitive analysis of work is still too close to a research activity rather than a practice. Beyond the protected frontiers of university laboratories and research departments of large corporations, cognitive engineering often draws more on intuition derived from operators' cognitive activities than from the results of rigorous methodological approaches. This hampers the expansion of cognitive ergonomics as a vehicle for transforming socio-technical systems. Developing practical means of applying cognitive ergonomics within the context of operation on the ground is, thus, a challenge to be met, if this scientific discipline is to contribute fully to the improvement of working systems on a daily basis.     

Changes in stress and subjective workload over time following a workload transition

Workload transitions present individuals with sudden changes in workload. These transitions may affect stress and coping behaviour. Two experiments were performed using a digit detection task that shifted between low and high workload levels to examine transition effects on performance, stress, and effort. The first experiment used a large magnitude transition and resulted in decreased estimates of task engagement and effort. Over time, the levels of subjective stress observed in the transitioned groups approached those of the non-transitioned control groups. The second experiment used a transition more moderate in magnitude. The results were similar to those from the first experiment except that the transition resulted in higher, sustained task engagement and effort. These findings indicate that over time, the perceived stress of transitioned individuals will approach those of non-transitioned individuals; however, the magnitude of the transition may influence individuals to either increase or decrease task-oriented, effortful coping.

Relevance to human factors/ergonomics theory

Previous research on the effect of workload transitions on experienced stress has produced conflicting results. Drawing upon transactional stress theory and motivational intensity theory, two experiments were conducted which resolve some of those conflicting findings. This research adds to our understanding of how workload transitions may affect individuals' experienced stress.     

Probing the effects of culture on the communication of websites design

Cultural diversity makes it impossible for designers to depend on instinctive knowledge or personal experiences. Therefore, it is vital to understand the requirements, communication patterns, and mental models of users from diverse cultures. The aim of this research is to probe whether incorporating cultural factors into web design can improve the web communication (usability). In this research, two cultures are selected based on Hofstede's cultural dimension model, and the local website audit is further constructed to check if there are significantly different preferences for a web interface design between two cultures (Taiwanese and Australian cultures). The web usability experiment is then established to test if those culturally preferred characteristics can improve the web communication (usability). The results of the usability test reveal that cultural preferences can facilitate the web communication. Furthermore, the suggestions for cross-cultural interaction design are concluded based on the results of the web communication evaluation.

Relevance to human factors/ergonomics theory

This research is relevant to human factors/ergonomics theory.     

Paying attention behind the wheel: a framework for studying the role of attention in driving

Driver inattention is thought to cause many automobile crashes. However, the research on attention is fragmented, and the applied research on driving and attention is further split between three largely independent traditions: the experimental research, the differential crash rate research, and the automation research. The goal of this review is to provide a conceptual framework to unify the research—a framework based on the combination of two fundamental dimensions of attentional selection: selection with and without conscious awareness (controlled and automatic), and selection by innate and acquired cognitive mechanisms (exogenous and endogenous). When applied to studies chosen to represent a broad range within the experimental literature, it reveals links between a variety of factors, including inexperience, inebriation, distracting stimuli, heads-up displays, fatigue, rumination, and secondary tasks such as phone conversations. This framework also has clear implications for the differential crash literature and the study of automated systems that support or replace functions of the driver. We conclude that driving research and policy could benefit from consideration of the different modes of attentional selection insofar as they integrate literatures, reveal directions for future research, and predict the effectiveness of interventions for crash-prevention.     

The technology of ergonomics

Attempts by the US Air Force, Human Factors and Ergonomics Society, and Board of Certification in Professional Ergonomics in the US, the Harmonization of European Training Programs for the Ergonomics Profession project group in Europe, and the International Ergonomics Association to determine the scope of ergonomics and its technology are reviewed. Based on these data, and the author's own observations of ergonomics internationally, the technology of ergonomics is defined as human-system interface technology (HSIT). HSIT is proposed to have five identifiable components. Each of these components is described, including a brief history of its development. Because it has developed a unique technology, the author concludes that ergonomics has evolved into a unique, stand-alone discipline that can be defined most directly by its technology. Further, that educating the general public about HSIT will increase public understanding of the nature and scope of ergonomics and its potential for enhancing organizational performance and the quality of human life.     

Workload control and optimised order release: an assessment by simulation

An important scheduling function of manufacturing systems is controlled order release. While there exists a broad literature on order release, reported release procedures typically use simple sequencing rules and greedy heuristics to determine which jobs to select for release. While this is appealing due to its simplicity, its adequateness has recently been questioned. In response, this study uses an integer linear programming model to select orders for release to the shop floor. Using simulation, we show that optimisation has the potential to improve performance compared to ‘classical’ release based on pool sequencing rules. However, in order to also outperform more powerful pool sequencing rules, load balancing and timing must be considered at release. Existing optimisation-based release methods emphasise load balancing in periods when jobs are on time. In line with recent advances in Workload Control theory, we show that a better percentage tardy performance can be achieved by only emphasising load balancing when many jobs are urgent. However, counterintuitively, emphasising urgency in underload periods leads to higher mean tardiness. Compared to previous literature we further highlight that continuous optimisation-based release outperforms periodic optimisation-based release. This has important implications on how optimised-based release should be designed.