Ergonomics
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Randomized Controlled Trial Clinical Trial
Use of auditory icons as emergency warnings: evaluation within a vehicle collision avoidance application.
In the context of emergency warnings, auditory icons, which convey information about system events by analogy with everyday events, have the potential to be understood more quickly and easily than abstract sounds. To test this proposal, an experiment was carried out to evaluate the use of auditory icons for an in-vehicle collision avoidance application. Two icons, the sounds of a car horn and of skidding tyres, were compared with two conventional warnings, a simple tone and a voice saying 'ahead'. ⋯ The auditory icons produced significantly faster reaction times than the conventional warnings, but suffered from more inappropriate responses, where drivers reacted with a brake press to a non-collision situation. The findings are explained relative to the perceived urgency and inherent meaning of each sound. It is argued that optimal warnings could be achieved by adjusting certain sound attributes of auditory icons, as part of a structured, user-centred design and evaluation procedure.
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This report presents the results of an ergonomics investigation into human thermal comfort using an automobile seat heated with an encapsulated carbonized fabric (ECF). Subjective and objective thermal comfort data were recorded while participants sat for 90 min in a heated and a non-heated automobile seat in an environmental chamber. Eight male participants each completed eight experimental sessions in a balanced order repeated measures experimental design. ⋯ Hand and foot comfort, sensation and temperature were similar in both seats. Asymmetric torso and thigh skin temperatures were higher in the heated seat although no significant discomfort was found in the front and back of the torso and thigh in either seat. Participants reported no significant difference in alertness between the control and heated seat.
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The purpose of this study was to examine the relationship between ratings of perceived exertion (RPE) and activity intensity, as determined by heart rate. Fifteen participants completed a standardized treadmill protocol in order to establish a heart rate--RPE calibration profile. These participants then completed two simulated occupational tasks--box carrying and sweeping. ⋯ There was a moderate, but statistically significant, correlation between monitored heart rate and heart rate predicted from RPE scores for both the box carrying (r = 0.70) and sweeping (r = 0.73) simulations. Direct prediction of task heart rate from RPE reported during the task was not as strongly correlated for the box carry (r = 0.11), as it was for the sweeping activity (r = 0.68). Results from this study suggested that heart rate monitoring alone does not account for enough of the variability resulting from both local and central mediation of RPE.
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Various levels of automation (LOA) designating the degree of human operator and computer control were explored within the context of a dynamic control task as a means of improving overall human/machine performance. Automated systems have traditionally been explored as binary function allocations; either the human or the machine is assigned to a given task. More recently, intermediary levels of automation have been discussed as a means of maintaining operator involvement in system performance, leading to improvements in situation awareness and reductions in out-of-the-loop performance problems. ⋯ Joint human/system option generation significantly degraded performance in comparison to human or automated option generation alone. Lower operator workload and higher situation awareness were observed under automation of the decision making portion of the task (i.e. selection of options), although human/system performance was only slightly improved. The implications of these findings for the design of automated systems are discussed.
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Accurate reporting of work-related conditions is necessary to monitor workplace health and safety, and to identify the interventions that are most needed. Reporting systems may be designed primarily for external agencies (OSHA or workers' compensation) or for the employer's own use. Under-reporting of workplace injuries and illnesses is common due to a variety of causes and influences. ⋯ A variety of influences may contribute to under-reporting; because of under-reporting, worker surveys and symptom reports may provide more valuable and timely information on risks than recordable injury logs. Safety incentive programmes should be carefully designed to ensure that they provide a stimulus for safety-related changes, and to discourage under-reporting. A case-control study of similar establishments, or data before and after instituting safety incentives, would be required to more clearly establish the role of these programmes in under-reporting.