Compensatory Tracking Task Research Articles

Effects of Task Structures on Attention Allocation Optimality

The experiment reported examined the hypothesis that more optimal allocations would occur between time-shared tasks that place heavy demands on common processing resources (similar task structures) than tasks that utilize separate resources (dissimilar task structures). Two dual task configurations differing in their degree of demand for common resources were employed. The structurally similar pairs consisted of two compensatory tracking tasks whereas the dissimilar pair consisted of a tracking and a short term memory task. Demand for common resources was further manipulated by employing four combinations of different I/O modalities for the memory task. Relative use of the task-specific resources were manipulated through priority instructions and dynamic difficulty changes. Results generally support the hypothesis and suggest that certain dimensions that defined the resources (stages of processing, I/O modalities, and processing codes) assert greater influence on allocation optimality than others. Implications for decisions on multitask designs were speculated.

Contributions of Congruent Pitch Motion Cue to Human Activity in Manual Control

The contributions of pitch motion cue to the performance of human pilots in compensatory tracking task are evaluated by seperating the visual contributions from the combined motion visual contributions wherein the visual cue is congruent to the motion cue. Analytical human pilot models of the Least Squares (LS) structure are evaluated from the pilot input-output in uniquely planned motion based research simulator experiments. Beneficial contributions of the pitch motion cues in the form of lead and prediction are demonstrated.

Tracking Performance With Varying Error-Criteria

A compensatory tracking task including an additional error condition is introduced. A number of experiments show that nonlinear manual control behaviour can be induced by the weight given to the error-conditions. Although it represents only a small part of the output-variance, it still may be of importance for the stability of a man-machine system. The adaptation of the human operator can be regarded as the selection of an optimal strategy on the basis of the weight given toconsequences of actions.

手動制御系研究の動向

In this article, the researches are reviewed that used purusit and compensatory tracking tasks without controlled element in which the command variable was either step or sinusoidal wave. Following an introductory chapter, Chapter 2 and 3 discuss the responses to step and sinusoidal wave respectively. The title of each section of Chapter 2 is as follows: 2.1 Linearity in human input-output system. 2.2 Adequate form of transfer function of human input-output system. 2.3 Determinating of human transfer function by means of t heoretical curve fitting. 2.4 Estimated curve of sinusoidal response computed from step response. The title of each section of Chapter 3 is as follows: 3.1 Specific character of sinusoidal response. 3.2 Transfer function of human inputoutput system. 3.3 Time variance course and non-linearity in dynamic characteristics of human input-output system. 3.4 Estimated curve of step response computed from sinusoidal response. References consist of 19 foreign and 15 Japanese papers.

Video-game and conventional tracking.

The performance evaluarion tests for environmental research (PETER) program is a series of studies involving extended practice on a variety of task. One of these tasks is a compensatory tracking task which requlres the subject to keep a moving circle centered in a horizontal track by making approptlate left-right manipulations of a control stick ( 1 ) . Eighteen subjeas practiced this task every working day for three consecutive weeks, 10 1-min. trials a day. Approximately 1 yr. later 10 of the same 18 subjects practiced a commercially available video game, Atari's Air Combat Maneuvering. The video task requires the subject to align a black approximately triangular attack jet with a same-sized white target or drone jet so that a fired missile will intercept ( 2 ) . These requirements traditionally define a pursuit tracking task. This task was also practiced 10 trials (games) a day every working day for three consecutive weeks; each game lasted 2 1/3 min. Differential stability refers to that point in practice after which individual learning curves are parallel and at most slowly increasing, except for random error; after this point all intertrial (interday) correlations are the same except for sampling variations ( 2 ) . Such constancy indicates that neither the subjects' strategies nor the nature of what is being measured are changing with practice, that is, the task has stabilized. Analysis is confined to stabilized trials (days) only. For the game the average correlation among stabilized trials was .93. The. average correlation between stabilized trials on the game and compensatory tracking was .78. The average correlation among stabilized trials in compensatory tracking was also .78. Hence, the correlation between game scores and compensatory tracking was as large as the reliability of the latter would allow. The implication is that the video game, a pursuit tracking task, measures the same thing at stabilized levels as compensatory tracking does, only more reliabiy. It appears, therefore, that this particular video game may have a future as a portable, low-cost substitute for traditional computer-driven laboratory tracking tasks. This future, moreover, may include predictive testing and training as well as evaluation of performance.

Personality and inter-subject differences in performance and physiological cost during whole-body vibration.

When subjects are exposed to whole-body vibration, extra effort is required to maintain pre-vibration standards of performance. Therefore the willingness of subjects to expend this effort might influence both performance and physiological cost. Willingness may be related to a personality variable-score on the locus of control scale. This hypothesis was tested in 12 subjects who performed a simulated driving task during 10 min of vertical (±Gz) whole-body vibration at energy levels of 021,0-28 and 0-35 r.m.s.g using a sinusoidal and a random waveform. Accuracy at a foot-controlled, compensatory tracking task, reaction time, oxygen uptake and heart rate were measured. Subjects with an ‘internal’ locus of control had less tracking error(p<0.001)and higher heart rates (p<0.05) than did subjects with an ‘external’ locus of control. Furthermore, both variables were significantly correlated with the locus of control scores (r= +0.73 and —0.66) respectively. These findings suggest that the inter-subject differences found in investigations using human subjects may be explained in part by personality differences related to locus of control.

Time on task effect on tracking performance under heat stress.

The time on task effect on human tracking performance under three levels of ambient temperature, namely; 20, 26 and 30°C wet-bulb globe temperature (WBGT) and under two different work/rest ratios (2/1 and 3/1) was investigated. Total exposure time in each session for the three temperature levels was 120 min while the time on task was 90 min. The work cycle time was kept constant at 30 min and each work session contained three cycles. The subjects in the experiment were six fit, acclimatized, undergraduate male students aged 20-23 years and the task need was a compensatory one-dimensional vertical tracking task. The statistical analysis of the results indicated that time on task had a significant detrimental effect ( p< 0.01) on tracking performance. As the time on task increased, the tracking performance decreased. The detrimental time on task effect on the tracking performance appeared to be greater in hot environments as demonstrated by the significant effect ( p< 0.1) of the time on task/ambient temperature interaction on tracking performance. A significant deterioration in tracking performance occurred after 25 min on task. When performing the task under hot environments, this effect was more pronounced. Ambient temperature was found to deteriorate the tracking performance significantly (p<0.01). By raising the ambient temperature from 20 to 26°C WBGT, the tracking error score was approximately doubled, while the rise of ambient temperature from 26 to 30°C WBGTdid not produce as great a deterioration in the tracking performance. Neither work/rest ratio nor its interaction with time on task or ambient temperature showed any significant effect on tracking performance. Finally, the results demonstrated that environmental siresses affect the homogeneity of a group of subjects. A group which was homogeneous for performance under comfort environment (20°C WBGT), became heterogeneous when worked under hot environments.

Effects of vestibular and visual motion perception on task performance

The effects of foveal and peripheral visual, as well as vestibular, cues on the performance and control behaviour of subjects in two different roll control tasks were studied in a moving base flight simulator with low noise motion characteristics. Two different roll control tasks were used, one being a following task (or compensatory tracking task) where a displayed random signal was to be tracked, the other being a disturbance task in which a random signal perturbed the controlled system and the roll angle was to be kept at zero. Consistent improvement in controller performance was found after adding visual peripheral or vestibular (motion) cues to the basic configuration consisting of a central CRT display. Control behaviour, as expressed by controller transfer functions, was also markedly influenced by the addition of these extra motion cues, the changes in control behaviour being dependent on the type of control task. Some possible causes for this dependence are discussed.

Multi-modal information processing for visual workload relief

The simultaneous performance of two single-dimensional compensatory tracking tasks, one with the left hand and one with the right hand, is discussed. The tracking performed with the left hand was considered the primary task and was performed with a visual display or a quickened kinesthetic-tactual (KT) display. The right-handed tracking was considered the secondary task and was carried out only with a visual display. Although the two primary task displays had afforded equivalent performance in a critical tracking task performed alone, in the dual-task situation the quickened KT primary display resulted in superior secondary visual task performance. Comparisons of various combinations of primary and secondary visual displays in integrated or separated formats indicate that the superiority of the quickened KT display is not simply due to the elimination of visual scanning. Additional testing indicated that quickening per se also is not the immediate cause of the observed KT superiority.

The cause of control movements in a tracking task.

The classical cause-effect or input-output model of behavior breaks down when there is feedback from response to stimulus. Using a compensatory tracking task it is shown that response variations on different occasions can be nearly identical while stimulus variations on these occasions are completely unrelated. This result seems to rule out stimulus variations as the cause of responses wh ich control (stabilize) the stimulus. When feedback exists, the cause of control must be viewed as an internal reference rather than an external stimulus.

Continuously Awake versus Suddenly Awakened Alert Crews: When Do You Want Your Decrement?

Previous research on “alert” crew performance under sudden arousal from sleep indicated performance decrements would persist for varying periods of time depending on task characteristics. These studies did not, however, address the alternative of continuously awake crews. Twelve males performed a dual axis, compensatory tracking task under two modes of standby alertness–continuously awake vs sleep-alert. Performance, oral temperature, and subjective ratings of fatigue were acquired during three intervals: pretest, 2000–2200; test, 0200–0400; and posttest, 0800–1000. For the awake mode the test performance in the middle of the night was indistinguishable from the pretest performance, but the posttest performance was markedly worse. For the sleep-alert mode tracking performance was noticeably degraded following sudden awakening, but posttest performance was virtually identical to pretest performance (Figure 1). From the pretest to the test interval, oral temperature decreased to a much greater extent for the sleep-alert mode than for the continuously awake mode (Figure 2). Under both modes, feelings of subjective fatigue increased from pretest to test intervals. At posttest, even greater fatigue was reported for the continuously awake mode, while some recovery was reported for the sleep-alert mode (Figure 3). For alert duty one must consider probability of required performance, error tolerances, and future performance requirements prior to scheduling decisions.

A Comparison of the Predictive Validities of Single- and Dual-Task Measures

An experiment comparing the predictive validity of single-versus dual-task measures is reported. Fifty-seven males received two trials on each of two identical one-dimensional compensatory tracking tasks followed by 25 dual-task trials. Finally, they performed each task alone for one trial. The subjects then were given a short basic flight course consisting of ground instruction and practice in a GAT-2 simulator. After completing the course, the subjects performed four repetitions of three maneuvers. Performance in the simulator then was correlated with performance on each tracking trial. The predictive validity of the early single-task scores decreased with practice while the dual-task validity increased throughout the testing session. However, the predictive validity of the late single-task scores was almost as large as that of the late dual-task scores.

The identification and transfer of timesharing skills

Performance on two different task combinations was examined for evidence that timesharing skills are learned with practice and can transfer between task combinations. One combination consisted of two discrete informaion processing tasks, a short-term memory task and a classification task; the other consisted of two identical one-dimensional compensatory tracking tasks. Three groups of 16 subjects were employed in the experiment. The first received dual-task training on both combinations; the second received single-task training on the discrete-task combination and dual-task training on the tracking combination; the third received dual-task training on the tracking combination only. Evidence for distinct timesharing skills was found in both combinations using a new technique designed to separate improvements in timesharing skills from improvements in single-task performance. Transfer of timesharing skills also was found. Several fine-grained analyses performed on the data from the discrete task combination and a Control Theory Analysis of the tracking data indicated that skills in parallel processing were learned in each combination and transferred between them.

Searching for traffic signals while engaged in compensatory tracking.

An experiment is described in which subjects were required to search for familiar traffic signals. Half the time this was done while also engaged in a manual compensatory tracking task. The experimental variables of the visual search task were color, total number of signals exposed, the number of relevant signals, and the density of the signals. The results showed performance degradation for both tasks when the visual search and the tracking tasks were performed concurrently. Examination of the main effects and interactions suggest that, except when color was a perfect cue, visual search was a sequential process. Other theoretical and practical implications are discussed.

Effect of cursor characteristics on pilots' tracking performance on a cathode-ray tube in dynamic simulation

The effects of cursor configuration, size, and orientation on the performance of 11 commercial airline pilots were investigated in a difficult compensatory tracking task in a moving-base aircraft simulator. Three levels of congruent cab motion (0, 1, and 2 times the visual motion) were superimposed on the tracking task. Data analysis of the mean tracking error scores revealed no significant effects of cursor size, orientation, or configuration on pilots' tracking performance. Mean tracking error did not significantly differ between the three levels of motion for the conditions with a single dot as the cursor. However, for the dotted and solid line cursors, tracking error significantly decreased from the no motion condition to the motion conditions. The addition of simulator motion significantly reduced tracking error for large cursors, but not for small ones such as a single dot

Unimanual and Bimanual Control in a Compensatory Tracking Task∗

Abstract This paper reports an experiment comparing the unimanual and bimanual control performance of human operators in a compensatory tracking task. Two variables of the control system dynamics, the target wave frequencies and the delayed visual feedback (DVF) of operator's hand control motion were also investigated. Target wave frequencies of 0.067 Hz, 0.167 Hz and 0.383 Hz, and DVF of 0.0, 0.2, 0.4, 0.8 and 1.5 s were used. The experiment was divided into one practice session run over four days and one experimental session of two days for each of the six subjects in the study. A computer system was designed to generate target wave patterns, to measure hand control motions, to regulate DVF conditions, and to record task data, all on a real-time basis. The results indicate that unimanual tracking was significantly superior to the bimanual tracking under DVF conditions and higher levels of wave frequency, but not under the zero DVF or low wave frequencies. Tracking performance in general degraded as a fu...

Dual-Loop Model of the Human Controller

A dual-loop model of the human controller in single-axis compensatory tracking tasks is introduced. This model possesses an inner-loop closure that involves feeding back that portion of controlled element output rate that is due to control activity. A novel feature of the model is the explicit appearance of the human's internal representation of the manipulator-controlled element dynamics in the inner loop. The sensor inputs to the human controller are assumed to be system error and control force. The former can be sensed via visual, aural, or tactile displays, whereas the latter is assumed to be sensed in kinesthetic fashion. A set of general adaptive characteristics for the model is hypothesized, including a method for selecting simplified internal models of the manipulator-controlled element dynamics. It is demonstrated that the model can produce controller describing functions that closely approximate those measured in four laboratory tracking tasks in which the controlled element dynamics vary considerably in terms of ease of control. An empirically derived expression for the normalized injected error remnant spectrum is introduced.

Baseline differences, attention, and age differences in time-sharing performance

The purpose of this experiment was to determine whether age differences noted when two tasks are performed concurrently can be accounted for in terms of age differences in single task baseline performance. Two groups of 12 8-year-olds and one group of 12 13-year-olds performed a compensatory tracking task and an auditory matching task, first alone and then time shared. The 8- and 13-year-old baseline groups performed baseline trials on each task prior to time-sharing trials. Each training group 8-year-old was randomly paired with a 13-year-old and given sufficient single task practice before time sharing to equate the 8- and 13-year-old pair members' baselines on both tasks. Results showed trained 8-year-olds to be indistinguishable from 13-year-olds in time sharing, whereas the 8-year-old baseline group showed significantly greater decrements in time-sharing and higher baseline scores on both tasks. These data provide support for the hypothesis that time-shared performance is directly related to level of baseline performance.

Transfer of Training on Manual Control Systems Differing in Short Period Frequency and Damping Characteristics

Each of four groups of 16 subjects was trained on one of four compensatory tracking tasks that differed with regard to short period natural frequency (Ωn) and damping characteristics (2ξΩn). After completion of the training sessions, the members of each group either transferred to a task on which they had not been trained or continued with their original task. Analysis of the training data indicated that relative task difficulty was largely determined by system damping which, however, had little effect on the amount of transfer during the transfer trials. The effect of system frequency was essentially reversed, and a marked interaction between training and transfer frequencies was observed in the transfer data. Similar results were obtained both with relative error scores and transinformation scores. Positive transfer was exhibited by most of the groups when they transferred to tasks on which they had not been trained.

Manipulating the Conditions of Training in Time-Sharing Performance

A one-dimensional compensatory tracking task and a digit-processing, reaction time task were combined to assess three aspects of training under time-sharing conditions: (1) manipulation of desired levels of dual-task performance: (2) training under equal and unequal task priorities: and (3) repeated sequencing of single/dual-task presentations. Six groups of 10 subjects each participated in the experiment. Larger performance improvements under time-sharing conditions were observed when desired performance indicators were computed relative to a dual-task rather than a single-task reference. Training under unequal task priorities revealed that tracking was more sensitive than the digit-processing task to priority differences. Tracking performance continued to improve during repeated single-task presentation, whereas digit processing improved only in the time-sharing conditions. These findings suggest that improvement on the tracking task is in the specific skill of tracking, while digit-processing improvement results from improved time-sharing ability.