Learner-controlled selection of tasks with different surface and structural features: Effects on transfer and efficiency

Surface task features are more salient than structural task features and thus easier to recognize for novices. It is predicted that the more salient the task features the better learners can choose personally relevant and varied tasks, which enhances learning transfer. To investigate this prediction, a 2 × 2 factorial experiment with 72 participants studied the effects of control over tasks that differ in their surface features (learner, program) and in their structural features (learner, program). Learner control over the selection of tasks with salient surface features enables learners to select personally relevant and varied tasks. This is believed to yield higher effectiveness (i.e., higher near and far transfer test performance) as well as higher efficiency (i.e., higher transfer test performance combined with lower associated mental effort). Learner control over the selection of tasks with non-salient structural features does not enable learners to select personally relevant and varied tasks and is therefore not expected to yield beneficial effects on learning. The results show positive effects of learner control over the selection of tasks with salient surface features for efficiency on the far transfer test but not for effectiveness. Theoretical and practical implications are discussed.     

Speech variability effects on recognition accuracy associated with concurrent task performance by pilots

Abstract

Pairs of pilots performed an aircraft warning classification task using an isolated-word speaker-dependent speech recognition system to record their responses. Task-induced stress was manipulated by means of different scoring procedures for the warning classification task and by inclusion of a competitive manual control task (Voorhees and Bucher 1984, Voorhees and Bucher 1985). High quality tape recordings were made of pilots’ speech spoken to the recognizer while performing under the different types of task loading. This speech was then analysed spectrographically for timing differences in the pilot's manner of speaking as a function of task loading, and of recognition accuracy associated with different types of task loading. Recognition errors were recorded by type for an isolated-word speaker-dependent system and by an off-line technique for a connected-word speaker-dependent system. While recognition errors increased with task loading for the isolated word system, there was no such effect for task loading when tape recordings of the same utterances were recognized by a connected word system. The results suggest areas for further improvements to speaker-dependent recognition algorithms and provide predictions of the types of recognition errors that can be expected with current recognition technology used by pilots under moderate to high levels of task loading.     

Learning with hypermedia: The influence of representational formats and different levels of learner control on performance and learning behavior

In this paper, two experiments on the use of hypermedia environments for learning about probability theory are reported. In Experiment 1a it was tested whether multimedia design principles (multimedia principle, modality principle, redundancy principle) are valid in hypermedia environments, despite the fact that hypermedia offers more learner control than multimedia. The results showed only little evidence for this validity, although the hypermedia environment entailed only a rather low level of learner control. In Experiment 1b it was investigated how learner control affects performance and how its possible impact is moderated by learners’ prior knowledge. A high level of learner control positively affected the effectiveness of instruction only with regard to intuitive knowledge, but was at the same time accompanied by large increases in learning time, thereby rendering the instruction inefficient. Unexpectedly, effects of learner control were not moderated by students’ prior knowledge. The results imply that the idea to use multimedia design principles for hypermedia learning is too simple and that the benefits and drawbacks of learner control depend heavily on learning objectives and time constraints.     

Instructional designs for the development of transferable knowledge and skills: A cognitive load perspective

This paper analyzes the main points and results of a set of the previous papers in this Special Issue from the point of view of developing characteristics of flexible—transferable—expertise. It focuses on cognitive load issues related to the acquisition of deep transferable knowledge structures and developing metacognitive and self-regulation skills. The contributions to this Special Issue demonstrate that appropriate instructional support and optimal levels of control over the learning processes, enhanced by self-explanation and self-visualization techniques, may enhance learners’ abilities to transfer their knowledge and skills. Better understanding of the role of germane cognitive load, as well as our abilities to measure different types of load and high-level cognitive processes are essential for further progress in this area.     

基于优先级和任务共享的工作流负载平衡研究

为了适应电子商务中迅速变化的流程环境和系统负载,需要在多个工作流引擎中分配工作量,以保证工作流引擎在高负载条件下可以保持一个可接受的性能.基于中间件技术的工作流负载平衡子系统是提供高可信赖性和高伸缩性的一种有效方法,但目前还存在许多不足,如没有从优先级的角度来区分流程,没有精确定义系统的负载,分析了工作流的主要特点,设计了基于优先级队列的,实现任务共享的,自适应负载系统,并通过实验定义了一个综合考虑系统处理能力和工作流负载特点的因子,这种设计已经在中科院软件所软件工程中心研制的OncePI工作流系统中得到实现,并在实际运用中检验了其可用性.     

Product features and task effects on experienced richness, control and engagement in voicemail browsing

A recent focus is on creating engaging user experiences with digital products and services such as voicemail. This study aims to design towards increased levels of engagement in voicemail browsing by using the ‘Richness, Control and Engagement’ (RC & E) framework. This framework explains the levels of engagement in terms of the levels of richness and control that are shaped by the features of a product and the user’s expertise. A product was developed that utilized gestures and sound to access digital voicemail contents. An experiment was conducted in which 28 participants interacted with the product while varying (1) the number of features of the user interface, (2) the amount of voicemail content and (3) the type of task. Results showed that the levels of engagement could be predicted according to the levels of richness and control experienced when a task-term was added to the framework. Implications of the refined RC & E framework for interaction design practice are discussed.     

Investigation of guessability of industrial safety signs: Effects of prospective-user factors and cognitive sign features

This study investigated the effects of prospective-user factors and five cognitive sign features on guessability of safety signs. Sixty Hong Kong Chinese subjects guessed the meanings and rated the sign features of 63 Mainland China safety signs. The prospective-user factors of working or site visit experience at laboratory or construction site, awareness of safety signs in daily life, injury experience due to ignorance of safety signs, and driving experience had significant effects on guessing performance. However, gender, Mainland China visit experience, and family member working at laboratory or construction site had no influence on guessing performance. The guessability scores varied with the five cognitive sign features viz. familiarity, concreteness, simplicity, meaningfulness, and semantic closeness. The guessability of safety signs was better when the signs were familiar, concrete, simple and meaningful and when the signs were associated with the underlying concepts. Overall, the findings showed that prospective-user factors and cognitive sign features are involved in effective communication of safety sign messages.

Relevance to industry

Posting of safety signs is a possible safety precaution measure that can be taken to attempt to reduce accidents and injuries in industrial undertakings. The findings of this study provide useful information for designing more user-friendly safety signs which could act as a reference for interface designers to develop more user-friendly safety signs in the future.     

Individual and group-based learning from complex cognitive tasks: Effects on retention and transfer efficiency

The effects of individual versus group learning (in triads) on efficiency of retention and transfer test performance in the domain of biology (heredity) among 70 high-school students were investigated. Applying cognitive load theory, the limitations of the working memory capacity at the individual level were considered an important reason to assign complex learning tasks to groups rather than to individuals. It was hypothesized that groups will have more processing capacity available for relating the information elements to each other and by doing so for constructing higher quality cognitive schemata than individuals if the high cognitive load imposed by complex learning tasks could be shared among group members. In contrast, it was expected that individuals who learn from carrying out the same complex tasks would need all available processing capacity for remembering the interrelated information elements, and, consequently, would not be able to allocate resources to working with them. This interaction hypothesis was confirmed by the data on efficiency of retention and transfer test performance; there was a favorable relationship between mental effort and retention test performance for the individual learners as opposed to a favorable relationship between transfer test performance and mental effort for the students who learned in groups.     

Work content influences on cognitive task load,emotional state and performance during a simulated 520-days' Mars mission

In high-risk domains such as human space flight, cognitive performances can be negatively affected by emotional responses to events and conditions in their working environment (e.g., isolation and health incidents). The COgnitive Performance and Error (COPE) model distinguishes effects of work content on cognitive task load and emotional state, and their effect on the professional's performance. This paper examines the relationships between these variables for a simulated Mars-mission. Six volunteers (well-educated and -motivated men) were isolated for 520 days in a simulated spacecraft in which they had to execute a (virtual) mission to Mars. As part of this mission, every other week, several computer tasks were performed. These tasks consisted of a negotiation game, a chat-based learning activity and an entertainment game. Before and after these tasks, and after post-task questionnaires, the participants rated their emotional state consisting of arousal, valence and dominance, and their cognitive task load consisting of level of information processing, time occupied and task-set switches. Results revealed significant differences between cognitive task load and emotional state levels when work content varied. Significant regression models were also found that could explain variation in task performance. These findings contribute to the validation of the COPE model and suggest that differences in appraisals for tasks may bring about different emotional states and task performances.     

Improving TCP fairness and performance with bulk transmission control over lossy wireless channel

The traditional windows-based TCP congestion control mechanism produces throughput bias against flows with longer packet roundtrip times; the flow with a short packet roundtrip time preoccupies the shared network bandwidth to a greater extent than others. Moreover, the blind window reduction that occurs whenever packets are lost decreases the network utilization severely, especially in networks with high packet losses. This paper proposes a sender-based TCP congestion control, called TCP-BT. The scheme estimates the network bandwidth depending on the transmission behavior of applications, and adjusts the congestion window by considering both the estimated network bandwidth and the packet roundtrip time to improve fairness as well as transmission performance. The scheme has been implemented in the Linux platform and compared with various TCP variants in real environments. The experimental results show that the proposed scheme improves transmission performance, especially in networks with congestion and/or high packet loss rates. Experiments in real commercial wireless networks have also been conducted to support the practical use of the proposed mechanism.     

Effects of age and its interaction with task parameters on lifting biomechanics

This study investigated the age-related differences in lifting biomechanics. Eleven younger and 12 older participants were instructed to perform symmetric lifting tasks defined by different combinations of destination heights and load magnitudes. Lifting biomechanics was assessed. It was found that the trunk flexion in the starting posture was 32% lower and the peak trunk extension velocity was 46% lower in older participants compared with those in younger ones, indicating that older adults tended to use safer lifting strategies than did younger adults. Based on these findings, we recommend that physical exercise programmes may be a more effective ergonomic intervention for reducing the risks of low back pain (LBP) in lifting among older workers, compared with instructions of safe lifting strategies. As for younger workers, instructions of safe lifting strategies would be effective in LBP risk reduction.     

The influence of virtual presence: Effects on experienced cognitive load and learning outcomes in educational computer games

Does the immersive design of an educational gaming environment affect learners’ virtual presence and how much do they learn? Does virtual presence affect learning? This study tries to answer these questions by examining the differences in virtual presence and learning outcomes in two different computer-based multimedia environments: a gaming environment with high immersive design vs. hypertext learning environment with low immersive design. As the main focus, the effect of virtual presence on learning is also explained and tested. By identifying virtual presence as a variable that may determine learning, it is argued that computer gaming environments present a new challenge for researchers to investigate, particularly, the effects of virtual presence on the immersive design of games in order to help designers to predict which instructional configurations will maximize learning performance. In general, results revealed that the high-immersive gaming environment leads to the strongest form of virtual presence but also decreased learning. Although regression analyses indicate that virtual presence positively influences trivial- and non-trivial learning outcomes, learners who learned in a low-immersive environment outperformed the gaming group. A mediation analysis showed that the relation between virtual presence and non-trivial learning outcomes is partly mediated through increased cognitive load.     

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.     

Computer-based feedback in linear algebra: Effects on transfer performance and motivation

Two studies investigated the effects on students' perceptions (Study 1) and learning and motivation (Study 2) of different levels of feedback in mathematical problems. In these problems, an error made in one step of the problem-solving procedure will carry over to the following steps and consequently to the final solution. Providing immediate feedback after an error is made could prevent such carry-over effects. Feedback given on all problem-solving steps was hypothesized to yield higher motivation and better learning than feedback on the final problem-solving step. Study 1 investigated students' perceptions of three feedback types: ‘on the final solution step’; ‘on all the solution steps at once’; and ‘on all the solution steps successively’. Feedback on all solutions steps was perceived by learners more positively than feedback on the final solution step. Study 2 investigated the learning and motivational effects of two types of feedback, namely, ‘feedback on the final solution step’ and ‘feedback on all the solution steps’. The hypotheses that feedback on all problem-solving steps would lead to more effective learning and higher motivation than feedback on the final solution step were confirmed. Our results support current efforts to implement step-wise feedback. The implications for further research and for the design of feedback are discussed.     

Effects of lumbar extensor fatigue and surface inclination on postural control during quiet stance

A number of work environments require workers to perform tasks on inclined surfaces. Such tasks, along with muscle fatigue, can impair postural control and increase falling risks. The objective of this study was to determine the effects of surface inclination angle, standing direction, and lumbar extensor fatigue on postural control during quiet standing. A group of 16 young, healthy participants were tested while standing on inclined surfaces before and after lumbar extensor fatigue (induced by repetitive isotonic exercise). Three inclination angles (0°, 18° and 26°) and three standing directions (uphill, downhill, and lateral facing) were examined. Postural control was assessed using several measures derived from center-of-pressure time series and subjectively perceived stability. Significant main and interactive effects of inclination angle and standing direction were found for all dependent measures. The adverse effects of standing on inclined surfaces were found to differ between the three standing directions. In general, dose-response relationships with inclination angle were evident, particularly in the lateral-facing direction. Fatigue-related effects differed between conditions, suggesting that the adverse effect of lumbar extensor fatigue on postural control depend on inclination angle and standing direction. These findings may facilitate the development of fall prevention interventions for work involving inclined surfaces.     

Speech-based cursor control using grids: modelling performance and comparisons with other solutions

Speech recognition can be a powerful tool for use in human?–?computer interaction, especially in situations where the user's hands are unavailable or otherwise engaged. Researchers have confirmed that existing mechanisms for speech-based cursor control are both slow and error prone. To address this, we evaluated two variations of a novel grid-based cursor controlled via speech recognition. One provides users with nine cursors that can be used to specify the desired location while the second, more traditional solution, provides a single cursor. Our results confirmed a speed/accuracy trade-off with a nine-cursor variant allowing for faster task completion times while the one-cursor version resulted in reduced error rates. Our solutions eliminated the effect of distance, and dramatically reduced the importance of target size as compared to previous speech-based cursor control mechanisms. The results are explored through a predictive model and comparisons with results from earlier studies.     

The effects of the number of links and navigation support on cognitive load and learning with hypertext: The mediating role of reading order

Problems in learning with hypertext systems have been claimed to be caused by high levels of disorientation and cognitive load. This was recognized by DeStefano and LeFevre [DeStefano, D., & LeFevre, J. -A., (2007). Cognitive load in hypertext reading: A review. Computers in Human Behavior, 23(3), 1616–1641.] who predicted an increase of cognitive load and impairment of learning for hypertexts with a higher number of links per page. From a practical perspective, several navigation support techniques, such as providing link suggestions, have been proposed for guiding learners and reducing cognitive overload. In an experiment, we tested DeStefano and LeFevre’s predictions as well as the usefulness of link suggestions. Participants used different versions of a hypertext, either with 3-links or 8-links per page, presenting link suggestions or not. We tested their cognitive load and learning outcomes. Results showed that there was a benefit of using link suggestions for learning, but no effect of number of links on learning was found. Moreover, the effects of our manipulations on cognitive load were mediated by the reading order that participants selected. Implications for research and the design of navigation support systems are discussed.     

Tracking control for boundary controlled parabolic PDEs with varying parameters: Combining backstepping and differential flatness

The combination of backstepping-based state-feedback control and flatness-based trajectory planning and feedforward control is considered for the design of an exponentially stabilizing tracking controller for a linear diffusion-convection-reaction system with spatially and temporally varying parameters and nonlinear boundary input. For this, in a first step the backstepping transformation is utilized to determine a state-feedback controller, which transforms the original distributed-parameter system into an appropriately chosen exponentially stable distributed-parameter target system of a significantly simpler structure. In a second step, the flatness property of the target system is exploited in order to determine the feedforward controller, which allows us to realize the tracking of suitably prescribed trajectories for the system output. This results in a systematic procedure for the design of an exponentially stabilizing tracking controller for the considered general linear diffusion-convection-reaction system with varying parameters, whose applicability and tracking performance is evaluated in simulation studies.