Individual differences and ergonomic factors in performance on a videotex-type task

This study manipulated ergonomic aspects of a videotex-type task and attempted to relate paper and pencil measures of field dependence-independence, intelligence, capacity to complete a computer science curriculum and attitudes toward computers, to the performance of novice users. Results indicated that fault-tolerant aspects of the software and the use of self-defined commands resulted in superior performance. In addition, field independence and higher intelligence were associated with better performance. No substantial relationship was found between ability to complete a computer science curriculum and performance on the task. Those subjects who expressed an 'awesome' view of the nature of computers appeared to perform less well and it was suggested that this may be related to their lack of experience, although it was not possible to statistically verify this interpretation.     

Fighter pilots’ heart rate,heart rate variation and performance during instrument approaches

Fighter pilots’ heart rate (HR), heart rate variation (HRV) and performance during instrument approaches were examined. The subjects were required to fly instrument approaches in a high-fidelity simulator under various levels of task demand. The task demand was manipulated by increasing the load on the subjects by reducing the range at which they commenced the approach. HR and the time domain components of HRV were used as measures of pilot mental workload (PMWL). The findings of this study indicate that HR and HRV are sensitive to varying task demands. HR and HRV were able to distinguish the level of PMWL after which the subjects were no longer able to cope with the increasing task demands and their instrument landing system performance fell to a sub-standard level. The major finding was the HR/HRV’s ability to differentiate the sub-standard performance approaches from the high-performance approaches.

Practitioner Summary:

This paper examined if HR and HRV were sensitive to varying task demands in a fighter aviation environment and if these measures were related to variations in pilot’s performance.     

Individual differences and the effects of an information aid in performance of a fault diagnosis task

Two experiments are reported that investigated the performance of operators in a fault diagnosis task. Naval engineers working in the Ship's Control Centre (SCC) on board of frigates of the Royal Netherlands Navy were asked to solve a number of unfamiliar fault problems. In the first experiment, it was shown that there was a high correlation (0·85) between the number of problems correctly solved and the availability of system knowledge. In addition there was an effect of the level of formal education. In a second experiment it was shown that the provision of a simple help facility that compensates for a lack of system knowledge leads to a substantial increase in the number of problems that were correctly solved. The percentage of correct solutions increased from 62 to 89%. This increase was the same for operators with either an electrical engineering or a mechanical engineering background although the former group performed slightly better than the latter. These results show that the conclusion of Morris and Rouse (1985a) that instruction in the theoretical principles on which a system is based is less effective than the training of diagnostic procedures, underestimates the importance of system knowledge for the solution of fault diagnosis problems.     

Quantitative assessment of effects of visual scanning on concurrent task performance

Much of the research in visual scanning has adopted a single task experimental paradigm. The characteristics of visual scanning in multi-task situations are largely unknown. A quantitative assessment of the effects of visual scanning on concurrent task performance was gained from two experiments. Subjects were required to perform a simulated driving task, which involved a primary pursuit tracking task and a discrete response task. The response task was one of simple information acquisition in the first experiment and of complex information integration in the second. The information acquisition task required subjects to search for a spatial or verbal target. The information integration task required them to search for a spatial or verbal target and then make a rule-based decision by integrating the information carried by current and previous targets. The two types of task involved either spatial or verbal material, whose location was displayed with 4 levels of spatial uncertainty. The results of the two experiments which were: 2 (single/dual task) × 2 (spatial/verbal material) × 4 (levels of uncertainty of target location) revealed unique characteristics of visual scanning in multi-task performance. The effects of visual scanning on task performance and subjective workload were more pronounced in the dual task conditions than in the single. Increases in scanning demand produced greater interference with a concurrent spatial task than with a verbal one when the location uncertainty of visual scanning was sufficiently high. Implications for multi-task human-machine interface design are discussed.     

Impact of automated decision aids on performance,operator behaviour and workload in a simulated supervisory control task

In studies reporting automation effects on overall system performance and on the operator, the methods used to measure workload often did not appropriately reflect the complexity of this construct. The present study addresses the impact of automation on operator workload and behaviour in process control fault management. Workload effects were assessed with subjective, cardiovascular and secondary task performance indicators. Interactions with the interface of the process control simulation directed at gathering information and controlling the system were recorded. Automation made operators more efficient, allowing faster fault management with less information sampling and control actions. Subjective workload ratings were significantly lower in the assisted conditions as compared to manual, which was not reflected in cardiovascular and secondary task measures. Participants' information sampling activity did not differ between medium and high level of automation. Results suggest that participants paid constantly high attention to their task even with highly automated support.     

Ergonomic factors on task performance in laparoscopic surgery training

This paper evaluates the effect of ergonomic factors on task performance and trainee posture during laparoscopic surgery training. Twenty subjects without laparoscopic experience were allotted into 2 groups. Group 1 was trained under the optimal ergonomic simulation setting according to current ergonomic guidelines (Condition A). Group 2 was trained under non-optimal ergonomic simulation setting that can often be observed during training in a skills lab (Condition B). Posture analysis showed that the subjects held a much more neutral posture under Condition A than under Condition B (p < 0.001). The subjects had less joint excursion and experienced less discomfort in their neck, shoulders, and arms under Condition A. Significant difference in task performance between Conditions A and B (p < 0.05) was found. This study shows that the optimal ergonomic simulation setting leads to better task performance. In addition, no significant differences of task performance, for Groups 1 and 2 using the same test setting were found. However, better performance was observed for Group 1. It can be concluded that the optimal and non-optimal training setting have different learning effects on trainees’ skill learning.     

The effects of data model representation method on task performance

Data models are frequently created with little thought about their layout. Our research examined how data models organized in a columnar fashion compared to equivalent data models which did not, by improving novice designer's performance in error detection, comprehension, and query construction.     

Investigation of task performance variations according to task requirements and alertness across the 24-h day in shift workers

The study investigated time-of-day effects on task performance in shift workers in different tasks (reaction time, discrimination, probe recognition, free recall), by varying task-specific features. On each of six recordings, each programmed on a different day and in a randomised order, operators rated alertness and performed different tasks. Self-rated alertness varied according to a typical diurnal trend. Time of day also affected reaction time (slower responses at 03:00 hours), discrimination performance (lower accuracy at 03:00 hours in the most difficult condition) and recall (superior recall at 07:00 and 11:00 hours following deeper processing at encoding). The data demonstrated time-of-day effects on cognitive processes also involved in many real-job activities, despite the lack of control for a number of exogenous factors known to interfere with performance in work settings. Since in the cognitively more loaded tasks, time-of-day effects depended on task conditions, the findings are of operational concern in shift-work situations involving differential task requirements. In a real-job setting, performance variations were observed according to time of day and task requirements in a set of cognitively more or less demanding tasks. Task-specific research across the 24-h day enables a better understanding of operators' tasks and the development of supporting technology.     

Investigation of task performance variations according to task requirements and alertness across the 24-h day in shift workers

The study investigated time-of-day effects on task performance in shift workers in different tasks (reaction time, discrimination, probe recognition, free recall), by varying task-specific features. On each of six recordings, each programmed on a different day and in a randomised order, operators rated alertness and performed different tasks. Self-rated alertness varied according to a typical diurnal trend. Time of day also affected reaction time (slower responses at 03:00 hours), discrimination performance (lower accuracy at 03:00 hours in the most difficult condition) and recall (superior recall at 07:00 and 11:00 hours following deeper processing at encoding). The data demonstrated time-of-day effects on cognitive processes also involved in many real-job activities, despite the lack of control for a number of exogenous factors known to interfere with performance in work settings. Since in the cognitively more loaded tasks, time-of-day effects depended on task conditions, the findings are of operational concern in shift-work situations involving differential task requirements. In a real-job setting, performance variations were observed according to time of day and task requirements in a set of cognitively more or less demanding tasks. Task-specific research across the 24-h day enables a better understanding of operators' tasks and the development of supporting technology.     

提高老人医护安全的可穿戴心率测护仪设计

为实现对患有心梗的老年人身体状况的自动化管理以及减轻监护人对特殊人群的监护压力,文章设计了一种老年人的实时监测系统;该系统以Arduino以及32位的STM32F103单片机控制,采用ADS1292、LMT70传感器通过AD采集电位电压数据,利用放大电路和信号处理电路等转换为心率以及温度值,ESP8266无线传输模块在建立TCP连接之后,将数据传送至服务器和将数据传送至OLED显示终端,实现了当监护人不在床前陪护的情况下,依然能够将老年人的身体状况信息传送到监护人的手机APP中,有效防止了在发生意外时,不能及时采取措施的情景;该设计经过测试表明,心率的测量准确度高达95.29%,体表温度的测量准确度高达99.937%;测试结果表明,该设计具有足够高的准确性以及可靠性,具有实际推广与应用价值。     

Thermal effects on human performance in office environment measured by integrating task speed and accuracy

We have proposed a method in which the speed and accuracy can be integrated into one metric of human performance. This was achieved by designing a performance task in which the subjects receive feedback on their performance by informing them whether they have committed errors, and if did, they can only proceed when the errors are corrected. Traditionally, the tasks are presented without giving this feedback and thus the speed and accuracy are treated separately. The method was examined in a subjective experiment with thermal environment as the prototypical example. During exposure in an office, 12 subjects performed tasks under two thermal conditions (neutral & warm) repeatedly. The tasks were presented with and without feedback on errors committed, as outlined above. The results indicate that there was a greater decrease in task performance due to thermal discomfort when feedback was given, compared to the performance of tasks presented without feedback.     

Error analysis of task performance with laptop in vibration environment

The present study investigates influences of vibration directions, vibration magnitudes, object sizes, object distances and angles of approach on producing errors while performing pointing and clicking activity on a laptop monitor similar to passengers working on moving trains. Attempts made outside the boundary of an object while performing the activity is registered as an error. The number of errors produced under different exposure conditions is computed. Higher vibration magnitudes, smaller size of the objects, and diagonal angular movements are found to create more errors and affected accuracy of the activity and hence showed difficulties to perform the activity.     

Presence and task performance: an approach in the light of cognitive style

The paper highlights the relationship between each of four bi-polar dimensions of personality cognitive style, such as extraversion–introversion, sensing–intuition, thinking–feeling and judging–perceiving, and the level of sense of presence experienced. Findings indicate that individuals who are more sensitive, more feeling or more introverted experience a higher level of presence. While not reaching statistical significance, differing cognitive styles appear to impact on task performance. The apparent negative relationship discovered between sense of presence and task performance should be considered in the light of task characteristics. We discuss the implications of these findings and how they contribute to an understanding of the complex relationship that exists between presence and task performance and how this subsequently ought to influence the design of virtual environments.     

Analysis of hand movements during the performance of positioning tasks

An electroacoustic method was developed to analyse hand movements in space. This method was used to analyse the control error of the hand-arm system during the performance of a simple cyclic positioning task. It could be shown that the traces of the hand movements become significantly more dispersed with increasing time at work.     

Effects of a standing and three dynamic workstations on computer task performance and cognitive function tests

Sedentary work entails health risks. Dynamic (or active) workstations, at which computer tasks can be combined with physical activity, may reduce the risks of sedentary behaviour. The aim of this study was to evaluate short term task performance while working on three dynamic workstations: a treadmill, an elliptical trainer, a bicycle ergometer and a conventional standing workstation. A standard sitting workstation served as control condition. Fifteen Dutch adults performed five standardised but common office tasks in an office-like laboratory setting. Both objective and perceived work performance were measured. With the exception of high precision mouse tasks, short term work performance was not affected by working on a dynamic or a standing workstation. The participant's perception of decreased performance might complicate the acceptance of dynamic workstations, although most participants indicate that they would use a dynamic workstation if available at the workplace.     

多传感节点生理信息检测系统设计

本设计主要对人体体温、心率和血氧值进行提取分析,对系统组成中的电源模块、光源驱动模块和光电接收模块、红外温度模块、心电信号提取模块和无线传输模块进行了硬件设计.采用过采样技术对心电信号进行提取,提高了信号的稳定性和连续性.实验结果表明,该设计电路结构简单,稳定性好,测量精度高,功耗低,能够满足日常监测要求.     

Driving monotonous routes in a train simulator: the effect of task demand on driving performance and subjective experience

Although monotony is widely recognised as being detrimental to performance, its occurrence and effects are not yet well understood. This is despite the fact that task-related characteristics, such as monotony and low task demand, have been shown to contribute to performance decrements over time. Participants completed one of two simulated train-driving scenarios. Both were highly monotonous and differed only in terms of the level of cognitive demand required (i.e. low demand or high demand). These results highlight the seriously detrimental effects of the combination of monotony and low task demands and clearly show that even a relatively minor increase in cognitive demand can mitigate adverse monotony-related effects on performance for extended periods of time. Monotony is an inherent characteristic of transport industries, including rail, aviation and road transport, which can have adverse impact on safety, reliability and efficiency. This study highlights possible strategies for mitigating these adverse effects. Practitioner Summary: This study provides evidence for the importance of cognitive demand in mitigating monotony-related effects on performance. The results have clear implications for the rapid onset of performance deterioration in low demand monotonous tasks and demonstrate that these detrimental performance effects can be overcome with simple solutions, such as making the task more cognitively engaging.     

Effects of moderate cold on performance of psychomotor and cognitive tasks

Two experiments were performed to study the effects of exposure to moderate cold ( + 5°C) on psychomotor and cognitive tasks requiring sustained attention. Twelve male and 12 female subjects participated. Skin and core temperatures, heart rate and subjective ratings were recorded. Considerable decrements in manual dexterity were found during exposure, but no effects on simple reaction time or speed of correct response were observed. The effects of cold on the performance of complex tasks were demonstrated as an increase in the number of errors and the speed of incorrect response and as an increase in the number of false alarms on two computerized performance tests. The results, indicating a negative effect of moderate cold exposure on tasks which require speed and which encourage erroneous responses, are discussed in terms of theories of arousal and distraction.     

Effects of different physical workload parameters on mental workload and performance

The design and evaluation of an occupational task should include an assessment of mental workload, since excessive levels of mental workload can cause errors or delayed information processing. Physically demanding work that is performed concurrently with a cognitive task may impact mental workload by impairing mental processing or decreasing performance. The primary objective of this study was to determine whether there is a differential effect of various types of physical activity on both mental workload and cognitive performance. Objective and subjective assessment tools (heart rate variability and visual analog scale) were used as indicators of mental workload, while correct responses during an arithmetic task reflected levels of performance. Thirty participants (ages 18-24 years) performed a combination of tasks inducing both physical and mental workload. Type of physical effort, frequency of movement, and force exertion level were manipulated to alter the workload associated with the physical activity. Changes in subjective ratings generally corresponded to changes in both performance on the arithmetic task and objective mental workload assessment. Some discrepancies occurred at the highest physical force exertion level as participants perceived an increase in effort to maintain the same level of performance. Further research is needed to determine the force exertion threshold, beyond which the physical effort required interferes with mental workload and/or cognitive performance.

Relevance to industry

Technological advancements have increased the requirement for many workers to execute cognitive tasks concurrently with physical activity. When designing and evaluating such situations it is important to determine the interactive effects of these activities. A simple, uni-dimensional tool is suggested as a screening tool to identify situations requiring excessive or increased mental workload that many degrade performance or place additional stress on the individual.     

The effect of transportation suit induced heat stress on helicopter underwater escape preparation and task performance

Although essential in an emergency such as a helicopter ditching, mandatory survival suits worn by civilian personnel may lead to heat strain during a normal flight. To explore the possibility that wearing a helicopter transportation suit impairs emergency performance, 11 individuals completed underwater escape procedures immediately following a pre-recorded emergency announcement (randomly played between 50 and 90 min) in two ambient temperature conditions (Thermoneutral = 21 °C and Hot = 34 °C). Mean skin and rectal temperatures were recorded throughout the trials, while situation awareness and thermal sensation/comfort were recorded on completion of trials. Results indicate that although mean skin and rectal temperatures were significantly higher at the end of both trials, escape procedures were not impaired. It can therefore be concluded that although conditions inside an offshore transport helicopter are perceived as being hot and uncomfortable, no deficits in escape performance should be expected in the first 90 min of flight.