Time-shared Tasks Research Articles

Measuring Temporal Awareness for Human-Aware AI

This research investigated human performance in response to task demands that may be used to convey information about the human to an artificial agent. We performed an experiment with a dynamic time-sharing task to investigate participants development of temporal awareness of the task event unfolding in time. Temporal awareness as an extension, or a special case, of situation awareness, may provide for useful measures of covert mental models applicable to numerous tasks and for input to human-aware AI agents. Temporal awareness measures may be used to classify human performance into the control modes in the contextual control model (COCOM): scrambled, opportunistic, tactical, and strategic. Twenty-one participants participated in a withinsubjects experiment with an abstract task of resetting four independent timers within their respective windows of opportunity. The results show that temporal measures of task performance are sensitive to changes in task disruptions and difficulty and therefore have promise for human-aware AI.

Attention control in a demanding dynamic time-sharing environment: An eye-tracking study

In this study, we examined different models of cognitive control in dynamic time-sharing situations. We investigated attentional allocation by registering participants’ eye movements while they performed a new time-sharing task that forced them to solve resource conflicts between subtasks through prioritization. Participants were monitoring four subtasks each requiring different amounts of visual attention and response frequencies. Participants’ attention allocation was operationalized in terms of the time spent dwelling on subtasks, the rate they visually sampled the tasks, and the duration of dwells. Additionally, the accuracy of responses and efficiency of time-sharing were estimated. In Experiment 1, we studied adaptation to a time-sharing environment in which priority order of the subtasks was kept constant from trial to trial. We found that the participants sampled the most important subtasks more frequently, spent more time on them, and shifted their gaze earlier to them than to less important subtasks. That is, they allocated their attention according to the subtask priorities. In Experiment 2, subtask priorities changed from trial to trial. Despite the higher demands of the constantly changing situation, participants again adapted to the varying priorities of the subtasks almost instantly. Our results suggest that performance in complex and dynamic time-sharing situations is not managed by a system relying on liberal resource allocation policies and gradual learning. Instead, the participants’ rapid adaptation is more consistent with tighter executive and authoritative control and intelligent use of prioritization information.

Time use behavior in single and time-sharing tasks

Human errors in aviation, process plants and other critical industries can result in dire consequences and hence it is essential to understand the operator behavior and task characteristics in order to improve task performance and safety. The time available and how it is used by the operator are important factors in multi-task situations. Polychrons are people, who favor doing multiple tasks at the same time, while monochrons prefer doing tasks in series. In this study, the strategy, performance and workload of monochrons and polychrons were evaluated in a single and dual control tasks. The task difficulty and multiple task priority were independent variables. Results indicated that polychrons switched between two tasks more than monochrons and achieved better performance when the tasks were equally important and difficult. When the priority between the tasks was different, monochrons changed their emphasis to the more important task even though polychrons did not change their strategy as dramatically as the monochrons. In addition, monochrons indicated significantly higher workload and difficulty than polychrons. Results of this study can be important for the development of training programs of personnel involved in time-critical operations.

Multi-Axis EDM CNC System Based on RT-Linux

In order to manufacture geometrically complex or hard material parts, a new kind of multi-axis electro-discharge machining (EDM) computer numerical control (CNC) system, which is based on RT-Linux platform, was presented. Dual-kernel structure of System is adopted: Linux and RT-Linux are used to realize Time-sharing tasks and Real-time tasks separately. The system is divided macroscopically into two parts: Real-time part and Time-sharing part, microcosmically into three modules: Real-time Control Module, Drive Module and CNC User Module. Through the communications among them, three modules construct the whole system. Rimed Turbine Blisk was experimentalized to validate the performance of the system. The process and the results implied that the system is Real-time, stable and reliable.

Development of a CNC System for Multi-Axis EDM and its Realization

This paper presents a new kind of multi-axis electro-discharge machining (EDM) computer numerical control (CNC) system which is based on RT-Linux platform. Binary kernel structure of EDM CNC System is proposed to handle real-time task and time-sharing task separately. The system is divided into three parts: CNC kernel module, CNC driver module and CNC user module. CNC kernel module implements CNC control function in of the software system, and implements the move control to the NC machine. CNC driver module is just as device driver level. CNC user module is user manage procedure. The experiment of rimed turbine blisk validates the performance of the system. The performance implied that the system is real-time, stable and reliable.

The design and implementation of a low-cost and programmable home automation module

This paper presents a home automation module with programmable control instructions (PCIs). Although it is implemented by using a low-cost 8-bit microcontroller with only 8 Kbytes of ROM spaces, a time-sharing task scheduler and 10 PCIs are included in the firmware. Timer and counter control, logic functions, and temperature control are examples of PCIs. Thanks to the design of pseudo nodes, these PCIs can also be combined to implement more complex functions that home automation needs. These modules, up to 65536 theoretically, share the same IP address, and can be found over the network via different port numbers. No dedicated home server is necessary because the network communication (TCP/IP) is handled by the module. A remote control and monitoring software is also developed to let users control the home automation modules on the Internet. The programmable home automation module has a lower cost and better cost/performance ratio than current home automation modules

Vitesse du processus et temps partagé : planification et concurrence attentionnelle

Summary : Process speed and time-sharing : Planning and attentional concurrence. This experiment, carried out on a dynamic microworld described to the subjects as the command of units fighting against forest fires, reproduces the results of a previous experiment (Hoc & Moulin, 1994), which showed a stability in performance between a high and a low process speed. By interposing a medium speed between the two extreme speeds, the present experiment showed an optimum effect that provides us with more evidence in favour of a strategy shift. Performance stability can be interpreted as the result of shifting from a reactive strategy to an anticipative one progressively reaching the subjects' competency limit. On the other hand, by introducing conditions of time-sharing task management (several fires), a progressive improvement in performance was shown in relation to the reduction of attentional concurrence at the planning step. Key words : dynamic situation, process speed, time-sharing, planning, attention.

Viability of resource theories in explaining time-sharing performance

The primary objective of the present research was to test for performance tradeoff induced by priority instructions with the purportedly unbiased optimum-maximum method. In Experiment 1, performance tradeoff was observed when the tracking task was optimized but not when the Sternberg memory task was optimized. It was hypothesized that the tracking task was protected by peripheral vision when subjects focused on the optimized memory task. The second experiment tested the generality of the results with additional variations of the task pairs selected to represent different degrees of shared resources. The extent of performance tradeoff and time-sharing efficiency varied systematically with the extent of predicted resource overlap between the time-shared tasks. The observed performance tradeoff was strongly indicative of subjects' voluntary allocation control. Further, subjective ratings suggested that such control was effortful. These results were supportive of multiple resource theories and the viability of resource explanation of task interference.

Tracking Hesitations as a Function of Task/Control Integration

This study examines the issue of compatibility between task requirements (integrated vs. independent) and control configurations (integrated vs. separated) in the context of a dual-task environment. In the two experiments reported here, subjects were required to time-share a continuous tracking task with a discrete response task. The results showed a greater number of tracking hesitations when these tasks were mapped to separate controls than when they were mapped to the same control, regardless of the level of task integration employed here. We conclude that integrated controls produce less hesitations for time-shared integrated tasks and displays, but can not make conclusions concerning the optimal control configuration for time-shared independent tasks. The results also highlight the multi-dimensional nature of the concept of task integration and suggest that display and temporal dimensions of the concept might outweigh the response dimension.

Eye movements and event-related brain potentials in reading

Experiments conducted on both normal and disordered populations have led to the hypothesis that the left hemisphere's specialization for language results from its control over motor activities. This control is reflected in the lateralized disruption of manual activity during cerebral time-sharing tasks. Recent studies have challenged this hypothesis, stating that the interference effects reflect both cognitive and motor mechanisms in the left hemisphere. This experiment investigates whether the left hemisphere's control over speech involves both of these components or is purely motor. The question was examined by measuring the effect of concurrent hemispheric activity on single-finger tapping rates. Forty subjects tapped under two conditions: speaking and listening. The data show there may be both motor and cognitive mechanisms involved in left-hemisphere control.

A Methodology for Investigating Heat Stress Selectivity Effects on Mental Performance

This paper outlines a methodology that can be used to investigate the selectivity patterns of heat stress effects. The adopted view is that heat stress causes performance to deteriorate because it depletes attentional resources. The term “selectivity” refers to the extent to which certain individual resource pools (the existence of which is postulated by multiple resource theories) are more susceptible to heat stress effects than others. The methodology consists of plotting performance of two time-shared tasks over time on the Performance Operating Characteristic (POC) space. Manipulating the difficulties of the paired tasks under the same environmental conditions (i.e., temperature level and exposure duration) produces a predictable change of the POC path. In particular, if the heat stress effects are non-selective, the POC path will rotate either clockwise or counter-clockwise depending on the task whose difficulty is increased. On the contrary, if the heat stress effects are selective, increasing the difficulty of a task will have no effect on the orientation of the POC path.

Novice and Experienced Drivers' Looking Behavior and Primary Task Control While Doing a Secondary Task

This study is addressed to time-sharing and primary task control during a secondary task as a function of driving experience. After about 1.5 h of test driving, when well-adapted to the experimental car, 23 novices (less than 5,000 km of driving) and 26 experienced drivers (more than 150,000 km) were asked to change a cassette in a cassette player on an ordinary two-lane road. The task was replicated three times. The results showed no difference between novice and experienced drivers in time-sharing (glance length at the in-car task and at the road), lateral position-keeping (lateral displacement as a function of time at in-car task) or control in relation to oncoming traffic. The only difference occurred in speed control, experienced drivers keeping their speed level constant while novices slowed down somewhat during the secondary task. These data showed, in a supervised experimental setting, a similar linear relationship between time spent on an in-car task and lateral displacement both for novice and experienced drivers, and a similar median time gap of about 2 s to an oncoming vehicle at the moment when both novice and experienced drivers shifted their gaze from the in-car task to the road.

Aging, exercise, and attention.

The authors investigated the relationship among aging, attentional processes, and exercise in 2 experiments. First they examined age differences on 2 attentional tasks, a time-sharing task and an attentional flexibility task. Young adults alternated attention between 2 sequenced tasks more rapidly and time-shared the processing of 2 tasks more efficiently than older adults. They then investigated the effects of aerobic exercise on the same 2 attentional tasks in older adults. Following the 10-week exercise program, older exercisers showed substantially more improvement in alternation speed and time-sharing efficiency than older controls. Interestingly, this exercise effect was specific to dual-task processing. Both groups of subjects showed equivalent effects on single-task performance. These results indicate that aerobic exercise can exert a beneficial influence on the efficiency of at least 2 different attentional processes in older adults.

Aging, exercise, and attention.

The authors investigated the relationship among aging, attentional processes, and exercise in 2 experiments. First they examined age differences on 2 attentional tasks, a time-sharing task and an attentional flexibility task. Young adults alternated attention between 2 sequenced tasks more rapidly and time-shared the processing of 2 tasks more efficiently than older adults. They then investigated the effects of aerobic exercise on the same 2 attentional tasks in older adults. Following the 10-week exercise program, older exercisers showed substantially more improvement in alternation speed and time-sharing efficiency than older controls. Interestingly, this exercise effect was specific to dual-task processing. Both groups of subjects showed equivalent effects on single-task performance. These results indicate that aerobic exercise can exert a beneficial influence on the efficiency of at least 2 different attentional processes in older adults.

Flexibility in Resource Allocation and the Performance of Time-Sharing Tasks

The extent and nature of the ability to control the allocation of mental resources between the components of a dual task was investigated in three separate experiments. Using a variable priority (demand) methodology it was found that subjects could manipulate their performance level, however their ability to meet specific demand levels was limited. Training subjects under single or dual-task conditions using a wide range of task demand significantly improved dual task performance and degree of control over resource allocation as compared to performance following practice under a narrow range of task demands or under single task fixed demand conditions. Single task performance among all groups improved to the same degree. It was concluded that training subjects under a wide range of task demands increases the range of performance levels over which mental resources can be flexibly allocated for those tasks and improves time sharing performance. Implications for the design of training for complex task performance are discussed.

The Structural Constraints and Strategic Control of Resource Allocation

Time-sharing performance was evaluated as a function of the structural configurations of the time-shared tasks and strategic resource-allocation training. A secondary task technique was employed with five task pairs that varied in their structural similarity. The primary task difficulty was time-varying within a trial. Consistent with a common finding in the literature, the global performance measures showed that the degree of task interference increased as the degree of shared resources between the time-shared tasks increased. The moment-by-moment performance, however, revealed that small task interference did not necessarily indicate that the primary task performance was consistently protected against the time-varying difficulty changes. Subjects' failure in protecting the primary task performance was attributed to two possible causes: a skill limitation in the control of resource allocation and a structural limitation inherent in the dual task configuration. This distinction was reinforced by the findi...

Hemispheric specialization of abacus experts in mental calculation: Evidence from the results of time-sharing tasks

Hemispheric specialization for mental calculation and verbal tasks in abacus (Soroban in Japanese) experts and control subjects was tested using time-sharing tasks. In Experiment 1, the effects of auditorily presented mental calculation and news-listening tasks on sequential finger tappings were examined. The results revealed that in the mental calculation condition, abacus experts showed greater interference effects on left hand tapping, whereas control subjects showed greater interference effects on right hand tapping (as compared to left hand). In the news-listening condition, abacus experts showed no hand difference while the controls showed greater interference effects on the right hand. In Experiment 2, the effects of visually presented mental calculation and word-reading tasks on sequential finger tapping were examined. The results revealed that in the mental calculation condition, abacus experts showed a non-significant tendency towards greater interference in the left hand whereas the controls showed no hand difference. In the word-reading condition, both abacus experts and controls showed greater interference in the right hand than in the left hand. In Experiment 3, intermediate and upper-rank abacus experts performed a similar task to Experiment 1 under two instruction conditions. The results of this control experiment confirmed that a greater left hand reduction in calculation of abacus experts is not due to subject's cognitive mode but due to the amount of abacus learning experience. These data suggest that (1) learning experiences can affect the pattern of cerebral specialization through the change of approaches to perform cognitive tasks, and (2) the right hemisphere engages in mental calculation for the abacus experts whereas the left hemisphere contributes to mental calculation in ordinary people having no experience of abacus learning.

Time-Sharing Visual and Auditory Tracking Tasks

Multiple resource theory suggests that distributing demands over separate resources will reduce resource competition and improve time-sharing efficiency. A recent hypothesis however suggests that the benefits of utilizing separate resources for the time-shared tasks may be mitigated if the two tasks are integrated. The present experiment examined the benefits of distributing the input demands of two tracking tasks as a function of task integrality. Visual and auditory compensatory tracking tasks were used. Timesharing two tracking tasks with the same order of control is said to be more integrated than with different orders of control. Results show that presenting the two tracking signals in two input modalities did not improve time-sharing efficiency. This was attributed to the difficulty insensitivity phenomenon. Whether utilizing the same control dynamics between the time-shared tasks could generate an integrality effect was unclear from the present data. A continuous auditory task that could offer comparable spatial information as the visual counterpart was proposed to be valuable for studying attentional processes, information display alternatives, and workload assessment.

Display/Control Integrality and Time-Sharing Performance

Time-sharing performance was investigated as a function of the display and response integrality of the time-shared tasks. A manual step-tracking task was time-shared with a Stroop task that could be responded to manually or by speech. A secondary task technique was employed to manipulate the resource allocation between the two tasks. Display integrality was manipulated by: (1) contingent processing of the different dimensions of the Stroop task, and (2) the “objectness” of the dual task display. Response integrality was manipulated by the number of responses required of the dual task and the response modality of the Stroop task. A prevalent resource competition effect between the manual responses of the two tasks were observed, supporting the concept of multiple resources. Results were also in concordance with Kahneman's object file model of attention; demonstrating that irrelevant elements within an object were difficult to ignore. The findings demonstrated the interactive effects of resource competition and task integrality on time-sharing performance.

To Speak or not to Speak: A Multiple Resource Perspective

The desirability of employing speech response in a dynamic dual task situation was discussed from a multiple resource perspective. A secondary task technique was employed to examine the time-sharing performance of five dual tasks with various degrees of resource overlap according to the structure-specific resource model (Wickens, 1980). The primary task was a visual/manual tracking task which required spatial processing. The secondary task was either another tracking task or a spatial transformation task with one of four input (visual or auditory) and output (manual or speech) configurations. The results show that the dual task performance was best when the primary tracking task was paired with the visual/speech transformation task. This finding was explained by an interaction of the S-C-R compatibility of the transformation task and the degree of resource competition between the time-shared tasks. Implications on the utility of speech response were discussed.