An integrated measure of display clutter based on feature content, user knowledge and attention allocation factors.

Existing measures of display clutter in the literature generally exhibit weak correlations with task performance, which limits their utility in safety-critical domains. A literature review led to formulation of an integrated display data- and user knowledge-driven measure of display clutter. A driving simulation experiment was conducted in which participants were asked to search 'high' and 'low' clutter displays for navigation information. Data-driven measures and subjective perceptions of clutter were collected along with patterns of visual attention allocation and driving performance responses during time periods in which participants searched the navigation display for information. The new integrated measure was more strongly correlated with driving performance than other, previously developed measures of clutter, particularly in the case of low-clutter displays. Integrating display data and user knowledge factors with patterns of visual attention allocation shows promise for measuring display clutter and correlation with task performance, particularly for low-clutter displays. Practitioner Summary: A novel measure of display clutter was formulated, accounting for display data content, user knowledge states and patterns of visual attention allocation. The measure was evaluated in terms of correlations with driver performance in a safety-critical driving simulation study. The measure exhibited stronger correlations with task performance than previously defined measures.

Cockpit displays of traffic information and pilot bias in time-to-contact judgments.

INTRODUCTION: Pilots are susceptible to over-reliance on distance when making relative time-to-contact (TTC) judgments of surrounding intruders, referred to as "the distance bias." We tested the effect of adding perceptual cues and an information feature to cockpit displays of traffic information to mitigate this bias. METHOD: There were 14 general aviation pilots who participated in a simulated flight scenario and were asked to make relative TTC judgments. Three levels of perceptual cue (blinking, color-change, and no-cue) were crossed with two levels of velocity data tag (present and absent) with identification of the highest risk intruder as a response. RESULTS: Perceptual cues were associated with more accurate high-risk intruder selection (color = 95.95% correct, blinking = 95.98%, no-cue = 87.89%), decreased response time (color = 3.68 s, blinking = 3.19 s, no-cue = 6.08 s), reduced visual attention demand (color = 57% of attention, blinking = 58%, no-cue = 62%), lower workload ratings (color = 28.38/100, blinking = 29.66/100, no-cue = 48.91/100), and higher performance confidence ratings (color = 83.92/100, blinking = 82.71/100, no-cue = 58.85/100) than the no-cue displays. There was no difference between blinking and color cue displays. The data tag was associated with lower response times (present = 4.13 s, absent = 4.50 s) and higher confidence ratings (present = 78.69/100, absent = 71.63/100) than displays without. Displays including the blinking cue, color-change cue, and data tag were preferred over displays that did not include these features (color = 8 pilots, blinking = 6, no-cue = 0). DISCUSSION: The added display features were effective in mitigating the effect of the distance bias on pilot performance measures and received favorable subjective ratings.

An empirical assessment of driver motivation and emotional states in perceived safety margins under varied driving conditions.

Motivation models in driving behaviour postulate that driver motives and emotional states dictate risk tolerance under various traffic conditions. The present study used time and driver performance-based payment systems to manipulate motivation and risk-taking behaviour. Ten participants drove to a predefined location in a simulated driving environment. Traffic patterns (density and velocity) were manipulated to cause driver behaviour adjustments due to the need to conform with the social norms of the roadway. The driving environment complexity was investigated as a mediating factor in risk tolerance. Results revealed the performance-based payment system to closely relate to risk-taking behaviour as compared with the time-based payment system. Drivers conformed with social norms associated with specific traffic patterns. Higher roadway complexity led to a more conservative safety margins and speeds. This research contributes to the further development of motivational models of driver behaviour. PRACTITIONER SUMMARY: This study provides empirical justification for two motivation factors in driver risk-taking decisions, including compliance with social norm and emotions triggered by incentives. Environment complexity was identified as a mediating factor in motivational behaviour model. This study also recommended safety margin measures sensitive to changes in driver risk tolerance.

Effects of handicraft sitting postures on lower trunk muscle fatigue.

The purpose of this study was to assess trunk muscle fatigue in seated handicraft tasks using surface electromyography (sEMG) and visual analogue scale (VAS) ratings for trunk discomfort, and to assess the relationship of these responses. Twenty-three participants were randomly assigned to assumed crossed-leg and heel sitting postures for 30 min. Normalised median frequency (NMF) slopes for lumbar multifidus (LM) and internal oblique (IO) muscles and VAS ratings were recorded. Results revealed that the crossed-leg posture produced significantly steeper NMF slopes for both sides of the LM and IO muscles than heel sitting. Greater VAS ratings were found in crossed-leg sitting posture than the heel sitting posture. The NMF slopes and the VAS ratings had significant negative correlations for both postures. Findings support heel sitting in handicraft tasks over crossed-leg sitting due to greater trunk muscle fatigue and discomfort during the latter posture. Results support VAS ratings as a complementary method to sEMG for identifying trunk muscle fatigue. Practitioner Summary: Trunk muscle fatigue in handicraft work is a potential risk for low back pain. Based on EMG and discomfort analyses, heel sitting is preferred to crossed-leg posture. Discomfort ratings are consistent with EMG measures in identifying trunk muscle fatigue in such postures.

Multidimensional measure of display clutter and pilot performance for advanced head-up display.

INTRODUCTION: This study was conducted to: develop a multidimensional measure of display clutter for advanced head-up displays (HUDs) incorporating enhanced and synthetic vision; assess the influence of HUD configuration on perceptions of display clutter, workload, and flight performance; model clutter scores in terms of visual display properties; and model flight performance in terms of subjective and objective clutter indices. METHODS: In a flight simulator, 18 pilots with different levels of flight experience flew approaches divided into three segments. Three HUD configuration sets were presented under two levels of flight workload. Pilot ratings of overall display clutter, its underlying dimensions, and mental workload were recorded along with flight performance measures. Display image analysis software was used to measure visual properties of the HUDs. RESULTS: The multidimensional measure of clutter showed internal consistency with overall perceived clutter. Calculated clutter scores were sensitive to HUD configurations and in agreement with a priori display classifications. There was a trend for the extremes of display clutter to cause higher workload and less stable performance due to cognitive complexity and a lack of information for high and low clutter displays, respectively. Multiple linear regression models of perceived clutter were developed based on HUD visual properties with predictive utility. Models of flight performance based on the clutter score and workload ratings were also developed, but with less predictive power. DISCUSSION: Measures and models of display clutter are expected to be applicable to the evaluation of a range of display concepts.

Smartphone-based systems for physical rehabilitation applications: A systematic review.

Tele-(remote) rehabilitation is attracting increased attention from society, including the research community and commercial marketplace with an estimated global market value of $160 billion. Meanwhile, mobile device-based healthcare ("mHealth") has appeared as a revolutionary approach to tele-rehabilitation practice. This paper presents a systematic review of the literature on smartphone-based systems designed for remote facilitation of physical rehabilitation. A total of 74 documents from Web of Science search results were reviewed. Systems were classified based on target medical conditions, and a taxonomy of technology was created along with identification of monitored activities. Beyond monitoring, some systems also provide patient-caregiver communication and progress management functions. The review identifies major research interests in stroke, cardiac disease, balance impairment and joint/limb rehabilitation; however, there is a lack of attention to other diseases. There are also few systems that have computerized existing clinical tests. On the basis of the review, design recommendations are formulated to encourage implementation of advanced functionalities, usability considerations, and system validation based on clinical evidence. Results of this study may help researchers and companies to design functions and interactions of smartphone-based rehabilitation systems or to select technology.

Effects of corrective insole on leg muscle activation and lower extremity alignment in rice farmers with pronated foot: a preliminary report.

BACKGROUND: Execution of strenuous activities in conjunction with slippery and viscous muddy working terrain in rice cultivation leads to a high prevalence of farmer musculoskeletal disorders and malalignments. Recommended intervention strategies originally designed for congenitally disabled individuals may also be applicable to farmers, including simple corrective wedges to reduce foot eversion. The objective of the present study was to conduct a preliminary investigation of the effects of corrective wedges on lower extremity muscle activity and alignment when subjects stood on flat rigid ground or muddy terrain, simulating typical work conditions encountered by the unique but populous Thai rice farming workforce. METHODS: Nine healthy farmers with pronated feet were recruited to participate and wedges were custom fabricated for each farmer based on physical therapy assessment and use of rapid prototyping techniques. Participants were asked to stand barefoot or with wedges on the two surface types. RESULTS: Results revealed foot pronation and knee valgus to improve (ranging, on average between 5.5 and 16.1 degrees) when participants were equipped with corrective wedges. The muscle activity of the peroneus longus and the tibialis anterior increased for muddy terrain, as compared with the rigid surface. In general, the wedges induced less tibialis anterior activity and greater peroneus longus activity, compared to when participants were standing barefoot. An elevation in evertor muscle activity may reflect stretching of the shortened muscle as a result of the reduced degree of foot pronation. CONCLUSIONS: Findings demonstrate potential benefits of corrective insole usage for farmers with pronated feet, including improved lower extremity alignment and invertor muscle activity reduction for both rigid and muddy terrains.

Effects of stretching on muscle activation in gas cylinder handling.

BACKGROUND: Previously, a stretching regimen was designed for manual material handling (MMH) of gas cylinders as a potential ergonomic solution for reducing occupational injury. No studies have made use of objective process measures, such as muscle activation levels, for evaluation of effects of stretching programs. OBJECTIVE: Examine acute effects of stretching on muscle activation levels and driver perceived level of exertion in gas cylinder handling during simulated delivery operations. METHODS: A within-subject experiment was conducted with eight male participants being subjected randomly to two conditions over a two-day period: stretching before delivery trials and no stretching. Surface electromyography and the Borg CR-10 scale for perceived exertion were used. RESULTS: Generally, results were variable among muscle responses. The extensor muscle bundle in the forearm was found to show a significant decrease (p = 0.0464) in activation level because of stretching. The anterior deltoid and trapezius significantly increased (p < .0001) the EMG activation level with stretching. Also counter to expectations, participants rated perceived exertion significantly higher (p = 0.0423) for trials preceded by stretching. CONCLUSIONS: This research indicates a muscle stretching regimen in advance of MMH activities has mixed effects on activation levels across muscles. It is possible that effects are attributable to body posture positions, or manner of muscle use, during actual work activities. Findings indicate that stretching prior to work activity does have an impact on specific muscle activation.

A usability assessment of riding lawn-mowing equipment with varying levels of design standards compliance.

The use of riding lawn equipment (RLE) is related to a significant number of accidents every year. To provide basis for product design and enhance user performance and safety, a usability and performance assessment of modern riding lawn-mowing tractor designs and features was conducted in a real-world test environment. Five current commercially available RLEs were tested with response measures including task performance time and accuracy, physiological workload, system usability scores (SUS), and subjective rankings of RLE models. This data was used to identify sensitivity of responses to variations in RLE design features and functionality. The data was also used to assess the validity of new tractor design standard conformance tool, the RLEval methodology. This tool made comprehensive evaluation of RLE models compliance with over 70 specific design standards and was applied by human factors experts. Experiment results revealed sensitivity of all response measures to design differences among the five RLE models, except the objective workload measures. Response measures including task performance, SUSs and subjective rankings showed partial agreement with the RLEval scores. In general, the study results demonstrated a comprehensive experimental methodology for usability and performance evaluations of RLEs as well as merit of using the RLEval as preliminary method to compare design features. Some aspects of the usability experimentation and the RLEval method appear to be complementary.

Perceived clutter in advanced cockpit displays: measurement and modeling with experienced pilots.

INTRODUCTION: Synthetic and enhanced vision systems (SVS and EVS) are being introduced into the cockpit to promote safety under workload conditions. Integration of existing iconic imagery with SVS and EVS displays may lead to perceptions of clutter. This research evaluated head-up display (HUD) features, including SVS, EVS, traffic collision avoidance system symbology, flight pathway (TUNNEL) guidance, and different primary flight display symbol sets, on pilot perceptions of clutter. A perceptual decomposition of the construct of clutter was also conducted. METHOD: During a simulated landing, 4 expert pilots viewed images of 16 HUD configurations. Pilots rated clutter for each image and the utility of pairs of terms for describing clutter. RESULTS: Results revealed all HUD features and two-way interactions to be significant in perceived clutter. Ratings increased with additional features. The presence of EVS, TUNNEL, and an expanded symbol set contributed the most. Regression models were developed to predict the likelihood of clutter ratings based on pilot perceptions of display characteristics. Pairs of terms found to have the greatest use for describing clutter included "redundant/orthogonal," "monochromatic/colorful," "salient/not salient," "safe/unsafe," and "dense/sparse" (in that order). A factor analysis revealed underlying display qualities explaining approximately 78% of variability in perceived clutter, including global density, feature similarity, feature clarity, and the dynamic nature of displays. These qualities corresponded with the display descriptor terms plus the terms "static/dynamic." DISCUSSION: The study provided information on the relationship of display features and pilot perceptions of clutter. We identified terminology pilots use to describe clutter and latent display variables that drive perceived clutter.

Muscle loading in exoskeletal orthotic use in an activity of daily living.

Strokes are the leading cause of major adult disability with up to 85% of U.S. survivors experiencing hemiparesis. Physical characteristics of upper-extremity exoskeletal orthotics, used in stroke rehabilitation, were evaluated in terms of performance of activities of daily living (ADL), perceived exertion, and muscle load. Simulated orthotic weight distributions, with total extremity loads of 0.81 kg, 1.25 kg and 2.27 kg, were evaluated along with a 0 kg control condition. Response measures included average shoulder/elbow muscle surface electromyography (sEMG) signal amplitude, quality of task completion and total rest time during performance, and Borg CR-10 scale ratings. Device weight distribution, or imposed shoulder moment, was found to have a significant effect on biceps brachii and anterior deltoid activation levels, percent task completion, total rest time, and perceived exertion ratings. Results suggest that heavier upper-extremity orthotics could cause undesirable effects in terms of muscle loading, performance and exertion; such adverse effects could potentially lead to lack of use during patient's rehabilitation.

Driver performance and attention allocation in use of logo signs on freeway exit ramps.

The objective of this research was to quantify the effects of driver age, ramp signage configuration, including number of panels, logo format and sign familiarity, on driver performance and attention allocation when exiting freeways. Sixty drivers participated in a simulator study and analysis of variance models were used to assess response effects of the controlled manipulations. Results revealed elderly drivers to demonstrate worse performance and conservative control strategies as compared to middle-aged and young drivers. Elderly drivers also exhibited lower off-road fixation frequency and shorter off-road glance durations compared to middle-aged and young drivers. In general, drivers adopted a more conservative strategy when exposed to nine-panel signs as compared to six-panel signs and were more accurate in target detection when searching six-panels vs. nine and with familiar vs. unfamiliar logos. These findings provide an applicable guide for agency design of freeway ramp signage accounting for driver demographics.

The role of driver age in performance and attention allocation effects of roadway sign count, format and familiarity.

White-on-blue logo signs are used to inform drivers of food, gas, lodging, and attraction businesses at highway interchanges. In this study, 60 drivers were asked to look for food and attraction targets on logo signs while driving in a realistic freeway simulation. The objective of the study was to quantify effects of the number of sign panels (six vs. nine), logo familiarity (familiar vs. unfamiliar), logo format (text vs. pictorial), and driver age (young, middle, and elderly) on performance, attention allocation and target identification accuracy. Results revealed elderly drivers to exhibit worse performance in comparison to middle-age and young groups even though they adopted a more conservative driving strategy. There was no significant effect of the number of panels, logo familiarity, and logo format on driver performance or attention allocation. In target identification, drivers were more accurate with familiar or text-based panels appearing in six-panel signs.

Biometric validation of a virtual reality-based psychomotor test for motor skill training.

Psychomotor tests have been applied in clinical therapy and laboratory research as tools for evaluating motor and cognitive skills. Some studies have developed computerized versions of such tests using virtual reality (VR) systems with haptic interface controls. These systems allow for increased flexibility in test delivery and accuracy in performance assessment. In this study, a VR-based computer simulation of the block design (BD) test (a standardized psychomotor task as part of an adult IQ test) was developed and compared with the physical version of the test. Performance was evaluated based on four types of muscle activation collected using electromyography (EMG), time spent in completing the task, and subjective ratings of workload. Results verified the VR-based task as physically comparable to the conventional BD test. The validated computerized psychomotor task may be applied for both experimental and clinical use in future studies.

Usability and Safety in Electronic Medical Records Interface Design: A Review of Recent Literature and Guideline Formulation.

OBJECTIVE: The objectives of this study were to (a) review electronic medical record (EMR) and related electronic health record (EHR) interface usability issues, (b) review how EMRs have been evaluated with safety analysis techniques along with any hazard recognition, and (c) formulate design guidelines and a concept for enhanced EMR interfaces with a focus on diagnosis and documentation processes. BACKGROUND: A major impact of information technology in health care has been the introduction of EMRs. Although numerous studies indicate use of EMRs to increase health care quality, there remain concerns with usability issues and safety. METHOD: A literature search was conducted using Compendex, PubMed, CINAHL, and Web of Science databases to find EMR research published since 2000. Inclusion criteria included relevant English-language papers with subsets of keywords and any studies (manually) identified with a focus on EMR usability. RESULTS: Fifty studies met the inclusion criteria. Results revealed EMR and EHR usability problems to include violations of natural dialog, control consistency, effective use of language, effective information presentation, and customization principles as well as a lack of error prevention, minimization of cognitive load, and feedback. Studies focusing on EMR system safety made no objective assessments and applied only inductive reasoning methods for hazard recognition. CONCLUSION: On the basis of the identified usability problems and structure of safety analysis techniques, we provide EMR design guidelines and a design concept focused on the diagnosis process and documentation. APPLICATION: The design guidelines and new interface concept can be used for prototyping and testing enhanced EMRs.

Ergonomics-related risk identification and pain analysis for farmers involved in rice field preparation.

BACKGROUND: A previous ergonomic screening of rice field preparation revealed farmer exposure to high risks of musculoskeletal disorders at the shoulders, hands, wrists and back. The screening method was not applied to muddy soil farming in which analysts could not observe farmer legs and feet. This study analyzed farmer pain in all stages of field preparation. OBJECTIVE: To examine the relationship of farmer experience and demographics to perceptions of pain and to identify body areas exposed to ergonomics risks, unknown to farmers. Results were expected to support interventions and guidelines for famers on physical behaviors towards minimizing risk of injury as well as validation of the screening approach. METHODS: Comparison of analyst screening results and farmer pain ratings using self-ratings and interviews. RESULTS: Farmer experience and age were significantly correlated with occurrence of pain and cramping. Less experienced farmers reported less pain in high-risk body parts (e.g., neck and lower back). More experienced farmers reported more pain in the legs, as compared with analyst risk ratings. CONCLUSIONS: Results demonstrated less experienced farmers to be unaware of critical areas of exposure to ergonomics risks. Correlation of farmer ratings of pain with analyst risk assessments support validity of the screening method for hazard identification and control.

The effects of visual and cognitive distractions on operational and tactical driving behaviors.

OBJECTIVE: This study tested the effects of two fundamental forms of distraction, including visual-manual and cognitive-audio distraction, with comparison under both operational and tactical driving. Strategic control remains for future study. BACKGROUND: Driving is a complex control task involving operational, tactical, and strategic control. Although operational control, such as lead-car following, has been studied, the influence of in-vehicle distractions on higher levels of control, including tactical and strategic, remains unclear. METHOD: Two secondary tasks were designed to independently represent visual-manual and cognitive-audio distractions, based on multiple resource theory. Drivers performed operational vehicle control maneuvers (lead-car following) or tactical control maneuvers (passing) along with the distraction tasks in a driving simulator. Response measures included driving performance and visual behavior. RESULTS: Results revealed drivers' ability to accommodate either visual or cognitive distractions in following tasks but not in passing. The simultaneous distraction condition led to the greatest decrement in performance. CONCLUSION: Findings support the need to assess the impacts of in-vehicle distraction on different levels of driving control. Future study should investigate driver distraction under strategic control.

A Cognitive Modeling Approach to Decision Support Tool Design for Anesthesia Provider Crisis Management.

Prior research has revealed existing operating room (OR) patient monitors to provide limited support for prompt and accurate decision making by anesthesia providers during crises. Decision support tools (DSTs) developed for this purpose typically alert the anesthesia provider to existence of a problem but do not recommend a treatment plan. There is a need for a human-centered approach to the design and development of a crisis management DST. A hierarchical task analysis was conducted to identify anesthesia provider procedures in detecting, diagnosing, and treating a critical incident and a cognitive task analysis to elicit goals, decisions, and information requirements. This information was coded in a computational cognitive model using GOMS (Goals, Operators, Methods, Selection rules) Language. An OR monitor interface was prototyped to present output from the cognitive model following ecological interface design principles. A preliminary assessment of the DST was performed with anesthesiology and usability experts. The anesthesiologists indicated they would use the tool in the perioperative environment and would recommend its use by junior anesthesia providers. Future research will focus on formal validation of the DST design approach and comparison of tool output to actual anesthesia provider decisions in real or simulated crises.

Effect of visual displays and locations on laparoscopic surgical training task.

The number of minimally invasive surgical (MIS) procedures has substantially increased since its introduction due to health and recovery benefits for patients. However, there are potential performance issues in MIS for surgeons due to perceptual processing demands associated with supporting technologies. Monitor location has been identified as a major factor influencing performance in these types of procedures. This study examined the effect of multiple monitors on performance during a laparoscopic surgical training task (peg transfer among instruments). Twenty-four novice subjects were exposed to different monitor conditions including a default position, a biomechanically compatible position, and a position collocated with the operating surface as well as the combination of the latter two. Subjective rankings and cognitive workload were also assessed. Results revealed a significant effect of monitor position on task time when compared to subjects' baseline training task time using the default monitor setup. Collocating the monitor with the operating surface was shown to be superior in terms of task time. There were no significant differences among monitor positions in terms of perceived workload. The results of this study provide an applicable guide for the design of MIS setups in the operating room to promote surgeon performance.

Analysis of alternative keyboards using learning curves.

OBJECTIVE: To quantify learning percentages for alternative keyboards (chord, contoured split, Dvorak, and split fixed angle) and understand how physical, cognitive, and perceptual demand affect learning. BACKGROUND: Alternative keyboards have been shown to offer ergonomic benefits over the conventional, single-plane QWERTY keyboard design, but productivity-related challenges may hinder their widespread acceptance. METHOD: Sixteen participants repeatedly typed a standard text passage using each alternative keyboard. Completion times were collected and subsequent learning percentages were calculated. Participants were asked to subjectively rate the physical, cognitive, and perceptual demands of each keyboard, and these values were then related to the calculated learning percentages. RESULTS: Learning percentage calculations revealed the percentage for the split fixed-angle keyboard (90.4%) to be significantly different (p < .05) from the learning percentages for the other three keyboards (chord, 77.3%; contour split, 76.9%; Dvorak, 79.1%). The average task completion time for the conventional QWERTY keyboard was 40 s, and the average times for the fifth trial on the chord, contoured split, Dvorak, and split fixed-angle keyboards were 346, 69, 181, and 42 s, respectively. CONCLUSIONS: Productivity decrements can be quickly regained for the split fixed-angle and contour split keyboard but will take considerably longer for Dvorak and chord keyboards. The split fixed-angle keyboard involved physical learning, whereas the others involved some combination of physical and cognitive learning, a result supported by the subjective responses. APPLICATION: Understanding the changes in task performance time that come with learning can provide additional information for a cost-benefit analysis when considering the implementation of ergonomic interventions.