Techniques of subjective workload assessment: a comparison of SWAT and the NASA-Bipolar methods

Abstract

Assessment of subjective workload is becoming increasingly important in the evaluation of human-machine systems. Two popular methods were compared: (1) the Subjective Workload Assessment Technique (SWAT) that employed a conjoint measurement procedure to confer interval scale properties on the workload ratings, and (2) a technique under development at NASA that used an individually weighted workload score. Both methods were applied in a laboratory experiment that required the rating of a number of single- and dual-tracking and spatial transformation tasks. Both subjective assessment techniques displayed similar sensitivity to the different task manipulations. However, both techniques failed to detect the resource competition effects in the dual-task performance, and were in general insensitive to response execution processing demands. A notable difference between the two techniques was that the NASA-Bipolar ratings consistently had a smaller between-subject variability than the SWAT ratings. Discussion of the results is centred around the issue of the validity of assessment of subjective workload in general, and the construct and concurrent validity of the two techniques in particular.     

计算机性能指标MIPS的适用性分析

长期以来，ＭＩＰＳ一直被视为衡量计算机运算速度的主要性能指标之一。近年来，由于计算机结构的变化，使人们开始意识到以ＭＩＰ衡量计算机的运算速度存在着问题，但，迄今为止，人们对这一问题还没有完全认识清楚，还在以不同的方式使用着ＭＩＰＳ。本文从ＭＩＰＳ的定义出发，结合实例，全面地分析了以ＭＩＰＳ值度量计算机或比较不同的计算机的运算速度所存在的问题以及可能导致的错误结论。进一步地，本文还讨论了在一定的限制     

Towards evidence-based guidelines for wise use of computers by children

This paper argues for the systematic development and presentation of evidence-based guidelines for appropriate use of computers by children. The currently available guidelines are characterised and a proposed conceptual model presented. Five principles are presented as a foundation to the guidelines. The paper concludes with a framework for the guidelines, key evidence for and against guidelines, and gaps in the available evidence, with the aim of facilitating further discussion.

Relevance to industry

The current generation of children in affluent countries will typically have over 10 years of computer experience before they enter the workforce. Consequently, the primary prevention of computer-related health disorders and the development of good productivity skills for the next generation of workers needs to occur during childhood.     

A new notion of part structure for natural language

In this paper a new notion of part structure for the semantics of natural language is presented: a notion of part structure that is relative to a situation and unlike extensional mereological notions, crucially involves conditions of integrity. The notion is motivated by a variety of different constructions of natural language.     

基于负载的任务运行时间预报模型

由于计算资源具有广域分布、异构、动态等特点,使得计算网格环境下资源管理和调度成为一个非常复杂且具有挑战性的问题。分布式系统的性能度量、分析及预报已变得日益重要,而精确预报任务的运行时间,对达到应用性能是至关重要的。该文描述了一个基于负载的任务运行时间预报系统模型,它是任务调度及资源分配算法的中心。     

Young children’s access and use of computers in family child care and child care centers

Forty eight family child care providers and 37 center-based providers completed surveys about the availability and use of computers for children in their care. In addition, the providers were asked about their attitudes towards technology and their own computer skills. The impact of setting type on computer placement and rules about their use did not differ very much by setting type. Several factors were associated with the amount of time children were reported to use the computers. Overall, it appears that child care providers had developmentally sensitive guidelines for fostering computer use in both child care settings.     

Working in a moving environment

The present paper provides a review of research and theories concerning the question of how and why working in a moving environment may affect performance. It is argued that performance decrements can be expected to occur as a result of general factors or as a result of specific impairments of particular human skills. General effects happen when environmental motion, simulated or real, reduces motivation (due to motion sickness), increases fatigue (due to increased energy requirements), or creates balance problems. Specific effects of moving environments on task performance may only be expected through biomechanical influences on particular skills such as perception (interference with oculomotor control) or motor skills (such as manual tracking). There is no evidence for direct effects of motion on performance in purely cognitive tasks.     

The relationship between computerization and performance: A strategy for maximizing the economic benefits of computerization

The relationship between computerization and several measures of overall firm performance is examined. Sample firms consisted of 138 wholesalers in a single industry with annual sales between one million and over ten million dollars. Three performance comparisons are presented: users versus non-users of computers, three levels of usage, and class of computer usage. Results indicate that computerization is related to overall performance. Non-users tend to be small firms with about average overall performance. On the other hand, firms owning computers and making extensive use of them in a variety of ways tend to be either very high or low performers. Possible explanations for these bi-modal results are presented.     

Performance implications of synchronization structure in parallel programming

The restricted synchronization structure of so-called structured parallel programming paradigms has an advantageous effect on programmer productivity, cost modeling, and scheduling complexity. However, imposing these restrictions can lead to a loss of parallelism, compared to using a programming approach that does not impose synchronization structure. In this paper we study the potential loss of parallelism when expressing parallel computations into a programming model which limits the computation graph (DAG) to series–parallel topology, which characterizes all well-known structured programming models. We present an analytical model that approximately captures this loss of parallelism in terms of simple parameters that are related to DAG topology and workload distribution. We validate the model using a wide range of synthetic and real-world parallel computations running on shared and distributed-memory machines. Although the loss of parallelism is theoretically unbounded, our measurements show that for all above applications the performance loss due to choosing a series–parallel structured model is invariably limited up to 10%. In all cases, the loss of parallelism is predictable provided the topology and workload variability of the DAG are known.     

谈计算机基础教学的设计

高职类计算机基础课的教学,必须符合高职的培养目标。以培养学生的能力为第一要任,主张教师要持职业教育观念,以学生为主体,突出课程能力目标,精心设计课程的项目载体,用任务训练学生的职业岗位能力。     

The implications of the national curriculum for the use of information technology in the primary school

Abstract The purpose of this paper is to examine the Information Technology requirements of the National Curriculum in English, Mathematics, Science and Design and Technology as they apply to key stages 1 and 2 (5 –11-year-olds), and to suggest the minimum knowledge and skills required by primary school teachers in order to meet the statutory requirements of the 1988 Education Reform Act.     

Skills,rules and knowledge in aircraft maintenance: errors in context

Automatic or skill-based behaviour is generally considered to be less prone to error than behaviour directed by conscious control. However, researchers who have applied Rasmussen's skill-rule-knowledge human error framework to accidents and incidents have sometimes found that skill-based errors appear in significant numbers. It is proposed that this is largely a reflection of the opportunities for error which workplaces present and does not indicate that skill-based behaviour is intrinsically unreliable. In the current study, 99 errors reported by 72 aircraft mechanics were examined in the light of a task analysis based on observations of the work of 25 aircraft mechanics. The task analysis identified the opportunities for error presented at various stages of maintenance work packages and by the job as a whole. Once the frequency of each error type was normalized in terms of the opportunities for error, it became apparent that skill-based performance is more reliable than rule-based performance, which is in turn more reliable than knowledge-based performance. The results reinforce the belief that industrial safety interventions designed to reduce errors would best be directed at those aspects of jobs that involve rule- and knowledge-based performance.     

中国企业吸收能力影响因素与作用的探索性研究

通过资源基础观和企业能力观的融合,重构中国企业吸收能力的概念,在对相关理论总结的基础上,通过访谈构建出企业吸收能力来源和作用模型,并通过小样本进行探测性实证研究,明晰了对吸收能力的理解,为大样本实证研究奠定了基础,对于中国企业增强吸收能力、促进企业绩效提升有积极的启示。     

基于工作过程系统化SQL数据库课程体系的开发与实施

高职高专教育是直接为社会经济建设一线培养应用性专门人才的教育,应该从企业实际工作岗位需求出发,按照岗位要求能力设置课程,也就是让学生针对工作岗位而学习。根据数据库相关工作岗位的能力要求,打破传统的按知识结构体系教学的课程模式,转变为以工作过程为中心组织课程内容,并让学生在完成具体项目的过程中学会完成相应工作任务,并构建相关理论知识,发展其岗位职业能力。     

Upper quadrant postural changes of school children in response to interaction with different information technologies

The objective of this study was to quantitatively analyse the sitting posture of school children interacting with both old (book) and new (laptop and desktop computers) information technologies to test the hypothesis that posture is effected by the type of information technology (IT) used. A mixed model design was used to test the effect of IT type (within subjects) and age and gender (between subjects). The sitting posture of 32 children aged 4?–?17 years was measured whilst they read from a book, laptop, and desktop computer at a standard school chair and desk. Video images were captured and then digitized to calculate mean angles for head tilt, neck flexion, trunk flexion, and gaze angle. Posture was found to be influenced by IT type (p?<?0.001), age (p?<?0.001) and gender (p?=?0.024) and significantly correlated to the stature of the participants. Measurement of resting posture and the maximal range of motion of the upper and lower cervical spines in the sagittal plane was also undertaken. The biophysical impact and the suitability of the three different information technologies are discussed.     

基于缓冲池描述的DBMS分层排队网络模型及其求解

针对OLAP查询的特点,提出基于缓冲池描述的DBMS分层排队网络模型,以构建这一模型为例示范构建DBMS分层排队网络模型的方法和步骤。对比分析分层排队网络模型的两种求解算法——MOL(the Method of Layer)和SRVN(the Stochastic Rendezvous of Network)在算法结构、模型限制、描述能力、求解精度上的差别,总结出模型参数获取的三种途径。     

The evolution of the Computers and Writing Conference, the second decade

This article, written for the twentieth anniversary of the Computers and Writing Conference, is the sequel to “The Evolution of the Computers and Writing Conference” (Computers and Composition, 12(3), November, 1995). The earlier article analyzed many of the intellectual concerns, values, and language expressed in presentations at the Computers and Writing Conference from 1982 to 1994. This article does the same for the second ten conferences, 1995-2004. Throughout the second decade, we have developed a new comfort with computers, expanded our idea of “writing” beyond the traditional essay, and gained a respected place in the academy. Computers and writing has become an institution. At the same time, we sometimes worry about losing control over our teaching and can feel overwhelmed by the size of the task we undertake. Many of our values have stayed the same; however, we are optimistic about the place of technology in our work and in the culture at large, we love to experiment, and we routinely weave ideas from other disciplines and other areas of our lives into our computers and writing research.     

Video task analysis in high performance teams

A task-specific video recording effort at a trauma centre was studied. Task analysis methodology and an expert review of videos was used to access cognitive aspects of work and performance. Data collection included questionnaires and video reviews that used a template approach to task analysis and audio recordings of the experts think aloud performance assessment. Among 48 video records of airway management, performance deficiencies were identified including communication failures, omission of preparatory and confirmatory checks and lack of patient vital signs monitoring that lessened the margin of patient safety and caused a life-threatening critical incident. The analysis of aggregate data from multiple such videos of airway management allowed detection of the performance problems and development of an equipment design change and a task/communication training algorithm. The performance improvement and the lessons learned from using video as data in a medical domain are described. Targeted video task analysis with expert review may be generalisable to other medical procedures and non-medical domains.     

No interference of task complexity with circadian rhythmicity in a constant routine protocol

Time course in task performance has been studied extensively. In particular, the investigation of circadian rhythmicity in task performance that varied in complexity. However, these studies disclosed heterogeneous outcomes. This could be the result of confounding exogenous factors, the use of diverse tasks, as well as accumulating sleepiness interfering with the underlying circadian drive. The present study varied task demands systematically within a single task and a dual task, using a constant routine protocol to examine the unmasked influence of the endogenous circadian oscillator on the periodicity of performance. Moreover, the subjects were divided into an early-start and a late-start group to estimate the potential interaction of circadian rhythmicity with the duration of prior wakefulness. The results revealed a distinct congruence in the circadian rhythms of all performance measures, with which prior wakefulness (<?40?h) did not interact. Also, single-task as well as dual-task complexity did not interfere with circadian rhythmicity. In conclusion, when sufficiently controlled for masking exogenous factors, task complexity is removed from the underlying circadian rhythms.     

Using task migration to improve non-contiguous processor allocation in NoC-based CMPs

In this paper, a processor allocation mechanism for NoC-based chip multiprocessors is presented. Processor allocation is a well-known problem in parallel computer systems and aims to allocate the processing nodes of a multiprocessor to different tasks of an input application at run time. The proposed mechanism targets optimizing the on-chip communication power/latency and relies on two procedures: processor allocation and task migration. Allocation is done by a fast heuristic algorithm to allocate the free processors to the tasks of an incoming application when a new application begins execution. The task-migration algorithm is activated when some application completes execution and frees up the allocated resources. Task migration uses the recently deallocated processors and tries to rearrange the current tasks in order to find a better mapping for them. The proposed method can also capture the dynamic traffic pattern of the network and perform task migration based on the current communication demands of the tasks. Consequently, task migration adapts the task mapping to the current network status. We adopt a non-contiguous processor allocation strategy in which the tasks of the input application are allowed to be mapped onto disjoint regions (groups of processors) of the network. We then use virtual point-to-point circuits, a state-of-the-art fast on-chip connection designed for network-on-chips, to virtually connect the disjoint regions and make the communication latency/power closer to the values offered by contiguous allocation schemes. The experimental results show considerable improvement over existing allocation mechanisms.