AUDITORY ALARMS IN THE INTENSIVE CARE UNIT: EXPERIMENTAL AND OBSERVATIONAL STUDIES

There are many problems associated with the number of auditory warnings in hospital environments such as the Intensive Care Unit. As the amount of medical technology used to monitor a patient's condition increases, there is a concomitant increase in the number of auditory warnings. Each piece of equipment has its own alarm and often the sounds used are inappropriate. For example, the sounds are often too loud, too insistent and are irritating to staff, distracting them from other tasks. A further feature of sounds used for auditory alarms is that there is, at present, no agreement between manufacturers on the types of sounds used. This means that the same item of equipment can have different alarms if produced by different manufacturers. Subsequently there is the potential for confusion between alarms to occur if sounds are similar. The research presented in this thesis aims to investigate the psychological dimension of confusion between alarm sounds and the correct identification of a set of twelve auditory warnings currently in use in the I.C.U. Derriford Hospital, Plymouth. Hence, the first set of experiments examines the learning and retention of the set of auditory warnings in a laboratory setting. However, the many problems regarding auditory warnings should not be considered in isolation and in order to determine the types of activities undertaken by staff in the I.C.U. environment when alarms are activated, two observational studies were undertaken. The first study used a video camera and the second study involved direct observation using two observers. A series of tasks were developed that used the multiple resources literature as a framework and also represented tasks undertaken in the environment of the I.C.U. In the second experiment, participants were again required to learn and retain the set of auditory warnings. The tasks were introduced during the return stage of the experiment in order to examine first, whether there was an effect on the primary task of correctly identifying the sounds and whether the confusions between sounds increased or changed, and second to examine performance on the secondary tasks. The results showed that for all experiments in general participants required few trials to learn the sounds and the information was retained for a period of over one week. The results also showed that features of some sounds were easier to learn than other sounds and that certain sounds were consistently confused during each experiment. When the tasks were introduced performance on the primary task remained fairly constant, with no overall change or increase in the number of confusions between sounds. However, there was a decrement in the performance of the secondary tasks, as predicted by the dual-task literature. In conclusion, the results suggest that identification of sounds may depend on a global, overall label for a sound, such as a 'melodic' sound or a 'continuous' sound, with the more intricate details undetected by participants. The results also suggest that participants in the laboratory may alter their strategies to maintain performance on the primary task, by either responding more rapidly to task demands or by consciously deciding not to respond to one of the secondary tasks.Royal Aircraft Establishment, Farnboroug

Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Technical approaches for measurement of human errors

Human error is a significant contributing factor in a very high proportion of civil transport, general aviation, and rotorcraft accidents. The technical details of a variety of proven approaches for the measurement of human errors in the context of the national airspace system are presented. Unobtrusive measurements suitable for cockpit operations and procedures in part of full mission simulation are emphasized. Procedure, system performance, and human operator centered measurements are discussed as they apply to the manual control, communication, supervisory, and monitoring tasks which are relevant to aviation operations

The Role of Trust as a Mediator Between System Characteristics and Response Behaviors

There have been several theoretical frameworks that acknowledge trust as a prime mediator between system characteristics and automation reliance. Some researchers have operationally defined trust as the behavior exhibited. Other researchers have suggested that although trust may guide operator response behaviors, trust does not completely determine the behavior and advocate the use of subjective measures of trust. Recently, several studies accounting for temporal precedence failed to confirm that trust mediated the relationship between system characteristics and response behavior. The purpose of the current work was to clarify the roles that trust plays in response behavior when interacting with a signaling system. Forty-four participants interacted with a primary flight simulation task and a secondary signaling system task. The signaling system varied in reliability (90% and 60%) within subjects and error bias (false alarm prone and miss prone) between subjects. Analyses indicated that trust partially mediated the relationship between reliability and agreement rate. Trust did not, however, mediate the relationship between reliability and reaction time. Trust also did not mediate the relationships between error bias and reaction time or agreement rate. Analyses of variance generally supported specific behavioral and trust hypotheses, indicating that the paradigm employed produced similar effects on response behaviors and subjective estimates of trust observed in other studies. The results of this study indicate that other mediating variables may offer more predictive power in determining response behaviors. Additionally, strong assumptions of trust acting as the prime mediator and operationally defining trust as a type of behavior should be viewed with caution

A Quantitative analysis of the mental workload demands of MRAP vehicle drivers using physiological, subjective, and performance assessments

United States Special Operations Command (USSOCOM) Operators and vehicle Commanders are specially trained United States military Warfighters that have the demanding task of operating or working onboard Mine Resistant Ambush Protected (MRAP) All Terrain Vehicles (M-ATVs). Their missions encounter significant mental demands resulting from fatigue, highly stressful situations, and interactions with Government Furnished Equipment (GFE). Excessive mental demands can be the primary factor leading to compromised vehicle communication, missed improvised explosive device (IED) detection, and increased incidents of vehicle roll-over. Research has demonstrated the consequences of mental overloading including increased errors, performance decrements, distraction, cognitive tunneling and inadequate time to appropriately process information. The objectives of this thesis were to evaluate the extent to which task-related factors impact the mental workload of Warfighters and to evaluate the consistency among the three categories of mental workload metrics. The 14 participants studied in this research were Marine Corps personnel who had heavy vehicle driving experience. Physiological, subjective and performance measures were collected during a four-segment course that progressed in difficulty and analyzed across all participants to assess changes in mental workload. It was found that task-related factors impacted the mental workload of Warfighters. The subjective metric was able to capture changes in workload more accurately than biosignals. Due to technical problems with the biosignal data, comparison of consistency across metrics was inconclusive. The subjective workload ratings were significantly different between course segments and experience levels. The experiment resulted in workload ratings that increased by as much as 94% between segments and were 18% higher among novice drivers. This study showed that mental workload fluctuates while driving in a stressful situation, despite training and experience, and consequently, detection performance will be impacted which could have very adverse consequences. There is the need for additional research to have a better understanding of the true impact of mental workload on MRAP vehicle drivers, especially in an operational environment

Making intelligent systems team players: Case studies and design issues. Volume 1: Human-computer interaction design

Initial results are reported from a multi-year, interdisciplinary effort to provide guidance and assistance for designers of intelligent systems and their user interfaces. The objective is to achieve more effective human-computer interaction (HCI) for systems with real time fault management capabilities. Intelligent fault management systems within the NASA were evaluated for insight into the design of systems with complex HCI. Preliminary results include: (1) a description of real time fault management in aerospace domains; (2) recommendations and examples for improving intelligent systems design and user interface design; (3) identification of issues requiring further research; and (4) recommendations for a development methodology integrating HCI design into intelligent system design

A Comparison Of Attentional Reserve Capacity Across Three Sensory Modalities

There are two theoretical approaches to the nature of attentional resources. One proposes a single, flexible pool of cognitive resources; the other poses there are multiple resources. This study was designed to systematically examine whether there is evidence for multiple resource theory using a counting task consisting of visual, auditory, and tactile signals using two experiments. The goal of the first experiment was the validation of a multi-modal secondary loading task. Thirty-two participants performed nine variations of a multi-modal counting task incorporating three modalities and three demand levels. Performance and subjective ratings of workload were measured for each of the nine conditions of the within-subjects design. Significant differences were found on the basis of task demand level, irrespective of modality. Moreover, the perceived workload associated with the tasks differed by task demand level and not by modality. These results suggest the counting task is a valid means of imposing task demands across multiple modalities. The second experiment used the same counting task as a secondary load to a primary visual monitoring task, the system monitoring component of the Multi-Attribute Task Battery (MATB). The experimental conditions consisted of performing the system monitoring task alone as a reference and performing system monitoring combined with visual, auditory, or tactile counting. Thirty-one participants were exposed to all four experimental conditions in a within-subjects design. Performance on the primary and secondary tasks was measured, and subjective workload was assessed for each condition. Participants were instructed to maintain performance on the primary task, irrespective of condition, which they did so effectively. Secondary task performance for the visual-auditory and visual-tactile conditions was significantly better than for the visual-visual dual task condition. Subjective workload ratings were also consistent with the performance measures. These results clearly indicate that there is less interference for cross-modal tasks than for intramodal tasks. These results add evidence to multiple resource theory. Finally, these results have practical implications that include human performance assessment for display and alarm development, assessment of attentional reserve capacity for adaptive automation systems, and training

Measuring working memory load effects on electrophysiological markers of attention orienting during a simulated drive

Intersection accidents result in a significant proportion of road fatalities, and attention allocation likely plays a role. Attention allocation may depend on (limited) working memory (WM) capacity. Driving is often combined with tasks increasing WM load, consequently impairing attention orienting. This study (n = 22) investigated WM load effects on event-related potentials (ERPs) related to attention orienting. A simulated driving environment allowed continuous lane-keeping measurement. Participants were asked to orient attention covertly towards the side indicated by an arrow, and to respond only to moving cars appearing on the attended side by pressing a button. WM load was manipulated using a concurrent memory task. ERPs showed typical attentional modulation (cue: contralateral negativity, LDAP; car: N1, P1, SN and P3) under low and high load conditions. With increased WM load, lane-keeping performance improved, while dual task performance degraded (memory task: increased error rate; orienting task: increased false alarms, smaller P3). Practitioner Summary: Intersection driver-support systems aim to improve traffic safety and flow. However, in-vehicle systems induce WM load, increasing the tendency to yield. Traffic flow reduces if drivers stop at inappropriate times, reducing the effectiveness of systems. Consequently, driver-support systems could include WM load measurement during driving in the development phase

Traffic Alert and Collision Avoidance System (TCAS): Cockpit Display of Traffic Information (CDTI) investigation. Phase 1: Feasibility study

The possibility of the Threat Alert and Collision Avoidance System (TCAS) traffic sensor and display being used for meaningful Cockpit Display of Traffic Information (CDTI) applications has resulted in the Federal Aviation Administration initiating a project to establish the technical and operational requirements to realize this potential. Phase 1 of the project is presented here. Phase 1 was organized to define specific CDTI applications for the terminal area, to determine what has already been learned about CDTI technology relevant to these applications, and to define the engineering required to supply the remaining TCAS-CDTI technology for capacity benefit realization. The CDTI applications examined have been limited to those appropriate to the final approach and departure phases of flight

The Effect of Task Load, Automation Reliability, and Environment Complexity on UAV Supervisory Control Performance

Over the last decade, military unmanned aerial vehicles (UAVs) have experienced exponential growth and now comprise over 40% of military aircraft. However, since most military UAVs require multiple operators (usually an air vehicle operator, payload operator, and mission commander), the proliferation of UAVs has created a manpower burden within the U.S. military. Fortunately, simultaneous advances in UAV automation have enabled a switch from direct control to supervisory control; future UAV operators will no longer directly control a single UAV subsystem but, rather, will control multiple advanced, highly autonomous UAVs. However, research is needed to better understand operator performance in a complex UAV supervisory control environment. The Naval Research Lab (NRL) developed SCOUT™ (Supervisory Control Operations User Testbed) to realistically simulate the supervisory control tasks that a future UAV operator will likely perform in a dynamic, uncertain setting under highly variable time constraints. The study reported herein used SCOUT to assess the effects of task load, environment complexity, and automation reliability on UAV operator performance and automation dependence. The effects of automation reliability on participants’ subjective trust ratings and the possible dissociation between task load and subjective workload ratings were also explored. Eighty-one Navy student pilots completed a 34:15 minute pre-scripted SCOUT scenario, during which they managed three helicopter UAVs. To meet mission goals, they decided how to best allocate the UAVs to locate targets while they maintained communications, updated UAV parameters, and monitored their sensor feeds and airspace. After completing training on SCOUT, participants were randomly sorted into low and high automation reliability groups. Within each group, task load (the number of messages and vehicle status updates that had to be made and the number of new targets that appeared) and environment complexity (the complexity of the payload monitoring task) were varied between low and high levels over the course of the scenario. Participants’ throughput, accuracy, and expected value in response to mission events were used to assess their performance. In addition, participants rated their subjective workload and fatigue using the Crew Status Survey. Finally, a four-item survey modeled after Lee and Moray’s validated (1994) scale was used to assess participants’ trust in the payload task automation and their self-confidence that they could have manually performed the payload task. This study contributed to the growing body of knowledge on operator performance within a UAV supervisory control setting. More specifically, it provided experimental evidence of the relationship between operator task load, task complexity, and automation reliability and their effects on operator performance, automation dependence, and operators’ subjective experiences of workload and fatigue. It also explored the relationship between automation reliability and operators’ subjective trust in said automation. The immediate goal of this research effort is to contribute to the development of a suite of domain-specific performance metrics to enable the development and/or testing and evaluation of future UAV ground control stations (GCS), particularly new work support tools and data visualizations. Long-term goals also include the potential augmentation of the current Aviation Selection Test Battery (ASTB) to better select future UAV operators and operational use of the metrics to determine mission-specific manpower requirements. In the far future, UAV-specific performance metrics could also contribute to the development of a dynamic task allocation algorithm for distributing control of UAVs amongst a group of operators