Hysteresis in Mental Workload and Task Performance: The Influence of Demand Transitions and Task Prioritization

Workload transition rate matters: Evidence from growth curve modeling

This research examined three specific gaps in the workload transition literature: (1) the impact of workload transition rate, (2) the applicability of current theoretical explanations, and (3) the variability of performance overall and over time. Sixty Naval flight students multitasked in an unmanned aerial vehicle control testbed and workload transitioned at three rates: slow, medium, or fast. Response time and accuracy were analyzed via growth curve modeling. Slow transitions had the largest decline in performance over time. Medium transitions had some of the slowest, but most accurate and consistent performance. Fast transitions had some of the fastest, but least accurate performance. However, all performance trends significantly varied, suggesting multiple theoretical explanations may apply and performance may also depend on the individual. Design guidance on how to maximize performance goals with transition rate is provided, but future research needs to study the theoretical explanations and impact of individual differences further.

Scan-based eye tracking measures are predictive of workload transition performance

Given there is no unifying theory or design guidance for workload transitions, this work investigated how visual attention allocation patterns could inform both topics, by understanding if scan-based eye tracking metrics could predict workload transition performance trends in a context-relevant domain. The eye movements of sixty Naval flight students were tracked as workload transitioned at a slow, medium, and fast pace in an unmanned aerial vehicle testbed. Four scan-based metrics were significant predictors across the different growth curve models of response time and accuracy. Stationary gaze entropy (a measure of how dispersed visual attention transitions are across tasks) was predictive across all three transition rates. The other three predictive scan-based metrics captured different aspects of visual attention, including its spread, directness, and duration. The findings specify several missing details in both theory and design guidance, which is unprecedented, and serves as a basis of future workload transition research.

Patterns in transitions of visual attention during baseline driving and during interaction with visual-manual and voice-based interfaces

Voice interfaces reduce visual demand compared with visual-manual interfaces, but the extent depends on design. This study compared visual demand during baseline driving with driving while using voice or manual inputs to place calls with Chevrolet MyLink, Volvo Sensus, or a smartphone. Mean glance duration and total eyes-off-road-time increased when using manual input compared with baseline driving; only eyes off road time increased with voice input. Confusion matrices developed with hidden Markov modelling characterise the similarity of glance sequences during baseline driving and while making phone calls. Glance sequences with the MyLink voice interface were misclassified as baseline driving more frequently than the other voice interfaces. Conversely, glance sequences with the Sensus and smartphone voice interfaces were more often misclassified as manual phone calling. Thus, the MyLink voice interface not only reduced the overall visual demand of placing calls, but produced glance patterns more similar to driving without another task. Practitioner Summary: The attention map and confusion matrix methodologies provide ways of characterising similarities and differences in glance behaviour across secondary task conditions, complementing traditional temporally based metrics (e.g. mean glance duration, long duration glances) while addressing some of the limitations of total-eyes-off-road-time (TEORT) for comparing secondary task behaviour to baseline driving.

Transitions Between Low and High Levels of Mental Workload can Improve Multitasking Performance

OCCUPATIONAL APPLICATIONS Complex and dynamic environments including military operations, healthcare, aviation, and driving require operators to transition seamlessly between levels of mental workload. However, little is known about how the rate of an increase in workload impacts multitasking performance, especially in the context of real-world tasks. We evaluated both gradual and sudden workload increases in the dynamic multitasking environment of an Unmanned Aerial Vehicle (UAV) command and control testbed and compared them to constant workload. Workload transitions were found to improve response time and accuracy compared to when workload was held constant at low or high. These results suggest that workload transitions may allow operators to better regulate mental resources. These findings can also inform the design of operations and technology to assist operators' management of cognitive resources, which include negating the adverse effects of vigilance decrements during low workload periods and data overload during high workload periods.

Cusp catastrophe models for cognitive workload and fatigue in teams

The use of two cusp catastrophe models has been effective for untangling the effects of cognitive workload, fatigue, and other complications on the performance of individuals. This study is the first to use the two models to separate workload and fatigue effects on team performance. In an experiment involving an emergency response simulation, 360 undergraduates were organized into 44 teams. Workload was varied by team size, number of opponents, and time pressure. The cusp models for workload and fatigue were more accurate for describing trends in team performance criteria compared to linear alternatives. Individual differences in elasticity-rigidity were less important than subjective workload and experimental conditions as control variables. Fluid intelligence within the team was an important compensatory ability in the fatigue model. Results further supported the nonlinear paradigm for the assessment of cognitive workload and fatigue and demonstrated its effectiveness for understanding team phenomena.

Workload and Performance: Associations, Insensitivities, and Dissociations

OBJECTIVE

The aim of this study was to distill and define those influences under which change in objective performance level and the linked cognitive workload reflections of subjective experience and physiological variation either associate, dissociate, or are insensitive, one to another.

BACKGROUND

Human factors/ergonomics frequently employs users' self-reports of their own conscious experience, as well as their physiological reactivity, to augment the understanding of changing performance capacity. Under some circumstances, these latter workload responses are the only available assessment information to hand. How such perceptions and physiological responses match, fail to match, or are insensitive to the change in primary-task performance can prove critical to operational success. The reasons underlying these associations, dissociations, and insensitivities are central to the success of future effective human-machine interaction.

METHOD

Using extant research on the relations between differing methods of workload assessment, factors influencing their association, dissociation, and insensitivity are identified.

RESULTS

Dissociations and insensitivities occur more frequently than extant explanatory theories imply. Methodological and conceptual reasons for these patterns of incongruity are identified and evaluated.

APPLICATION

We often seek convergence of results in order to provide coherent explanations as bases for future prediction and practical design implementation. Identifying and understanding the causes as to why different reflections of workload diverge can help practitioners toward operational success.

Subjective and Objective Quantification of the Effect of Distraction on Physician's Workload and Performance During Simulated Laparoscopic Surgery

Background

Distracting interference cognitive tasks place undeniable pressure on the minds of people who need high precision and attention during the tasks, such as those tasks performed during surgery; these tasks might affect current surgical procedures. We measured the effect of additional cognitive tasks on the mental load of the physician by measuring the mean change in pupil size, blink rate, and subjective assessment during surgery.

Material/Methods

We recruited 24 participants with different levels of laparoscopic surgery to perform a complete appendectomy using a standardized virtual reality laparoscopic surgery simulator. The participants then performed the cognitive task (arithmetic problem), after that they performed an appendectomy surgery task while completing the cognitive task on the simulator. All participants wore trackers to monitor pupil size and blink rate during surgery and the cognitive task. The National Aeronautics and Space Administration (NASA) Task Load Index (TLX) score also recorded performance parameters during the surgical mission.

Results

The double-task pupil size and the blink rate were significantly increased compared to the single-task observation, and the associated increase in psychological load might have been affected by surgical performance, and the performance parameters were also statistically significant. However, for the aforementioned parameters, experienced surgeons had some differences compared with inexperienced surgeons, but these differences did not reach statistical significance.

Conclusions

Distracted cognitive task stimulation in the operating room can increase the surgeon’s psychological burden while also affecting their operational skills, thereby threatening patient safety; reduced cognitive costs might be obtained by improving or managing cognitive deficits.

Neural Correlates of Workload Transition in Multitasking: An ACT-R Model of Hysteresis Effect

This study investigated the effect of task demand transitions at multiple levels of analysis including behavioral performance, subjective rating, and brain effective connectivity, while comparing human data to Adaptive Control of Thought-Rational (ACT-R) simulated data. Three stages of task demand were designed and performed sequentially (Low-High-Low) during AF-MATB tasks, and the differences in neural connectivity during workload transition were identified. The NASA Task Load Index (NASA-TLX) and the Instantaneous Self-Assessment (ISA) were used to measure the subjective mental workload that accompanies the hysteresis effect in the task demand transitions. The results found significant hysteresis effects on performance and various brain network measures such as outflow of the prefrontal cortex and connectivity magnitude. These findings would assist in clarifying the direction and strength of the Granger Causality under demand transitions. As a result, these findings involving the neural mechanisms of hysteresis effects in multitasking environments may be utilized in applications of neuroergonomics research. The ability to compare data derived from human participants to data gathered by the ACT-R model allows researchers to better account for hysteresis effects in neuro-cognitive models in the future.

Quantitative Evaluations of the Effects of Noise on Mental Workloads Based on Pupil Dilation during Laparoscopic Surgery

Noise can exert undeniable pressure on human minds, especially during tasks that require high precision and attention, such as those performed during surgery. To investigate whether auditory stimuli increases mental loads during laparoscopic surgery, we examined the effects of operating room (OR) noises and music by measuring mean changes in pupil sizes and subjectively assessing performances during surgery. We recruited 24 subjects with varying laparoscopic surgery experience levels to perform complete appendectomy using a laparoscopic simulator. Wearable eye trackers were worn by all subjects to monitor pupil sizes during surgery, and surgical tasks were performed under conditions of silence, background OR noise, and music. National Aeronautics and Space Administration-Task Load Index scores and performance parameters were also recorded during surgical tasks. Noise distractions were associated with significant increases in pupil sizes compared with those observed in silence, and the related increases in mental loads may have affected surgical performance. However, more experienced operators had smaller changes in pupil sizes because of auditory disturbances than moderately experienced surgeons. Noise stimulation in the OR increases surgeon's mental workload and performance. Auditory regulation of the OR may be better standardized using data from studies of the effects of acoustic stimulation in the OR, and mental stresses during surgery could be considered in a more humane manner. Further investigations are necessary to determine the cognitive consequences of various auditory stimuli.

Correlative Evaluation of Mental and Physical Workload of Laparoscopic Surgeons Based on Surface Electromyography and Eye-tracking Signals

Surgeons’ mental and physical workloads are major focuses of operating room (OR) ergonomics, and studies on this topic have generally focused on either mental workload or physical workload, ignoring the interaction between them. Previous studies have shown that physically demanding work may affect mental performance and may be accompanied by impaired mental processing and decreased performance. In this study, 14 participants were recruited to perform laparoscopic cholecystectomy (LC) procedures in a virtual simulator. Surface electromyography (sEMG) signals of the bilateral trapezius, bicipital, brachioradialis and flexor carpi ulnaris (FCU) muscles and eye-tracking signals were acquired during the experiment. The results showed that the least square means of muscle activity during the LC phases of surgery in an all-participants mixed effects model were 0.79, 0.81, and 0.98, respectively. The observed muscle activities in the different phases exhibited some similarity, while marked differences were found between the forearm bilateral muscles. Regarding mental workload, significant differences were observed in pupil dilation between the three phases of laparoscopic surgery. The mental and physical workloads of laparoscopic surgeons do not appear to be generally correlated, although a few significant negative correlations were found. This result further indicates that mental fatigue does markedly interfere with surgeons’ operating movements.

Measuring Resilience

OBJECTIVE

As human factors and ergonomics (HF/E) moves to embrace a greater systems perspective concerning human-machine technologies, new and emergent properties, such as resilience, have arisen. Our objective here is to promote discussion as to how to measure this latter, complex phenomenon.

BACKGROUND

Resilience is now a much-referenced goal for technology and work system design. It subsumes the new movement of resilience engineering. As part of a broader systems approach to HF/E, this concept requires both a definitive specification and an associated measurement methodology. Such an effort epitomizes our present work.

METHOD

Using rational analytic and synthetic methods, we offer an approach to the measurement of resilience capacity.

RESULTS

We explicate how our proposed approach can be employed to compare resilience across multiple systems and domains, and emphasize avenues for its future development and validation.

CONCLUSION

Emerging concerns for the promise and potential of resilience and associated concepts, such as adaptability, are highlighted. Arguments skeptical of these emerging dimensions must be met with quantitative answers; we advance one approach here.

APPLICATION

Robust and validated measures of resilience will enable coherent and rational discussions of complex emergent properties in macrocognitive system science.