Evaluation of a psychophysiologically controlled adaptive automation system, using performance on a tracking task.

Three experiments were conducted to evaluate the performance of a psychophysiologically controlled adaptive automation system. Subjects were asked to perform a compensatory tracking task while their electroencephalogram (EEG) was recorded and an engagement index was derived from the EEG, using the alpha, beta, and theta bandwidths: beta/(alpha + theta) and beta/theta. In Experiment I, EEG was recorded from three different sites: frontal, parietal, and temporal. Although tracking performance did not differ as a function of site, the number of task mode allocations was greater under a negative feedback contingency than under a positive feedback contingency. This effect was seen primarily from frontal sites. Experiments II and III evaluated the adaptive automation system, using extended runs under positive and negative feedback with either a slope (Experiment II) or absolute (Experiment III) criterion used to drive the system. Using either criterion, performance was found to be significantly better under negative feedback. Future evaluation and use of psychophysiologically controlled adaptive automation systems are discussed.

A closed-loop system for examining psychophysiological measures for adaptive task allocation.

A closed-loop system was evaluated for its efficacy in using psychophysiological indexes to moderate workload. Participants were asked to perform either 1 or 3 tasks from the Multiattribute Task Battery and complete the NASA Task Load Index after each trial. An electroencephalogram (EEG) was sampled continuously while they performed the tasks, and an EEG index (beta/alpha plus theta) was derived. The system made allocation decisions as a function of the level of operator engagement based on the value of the EEG index. The results of the study demonstrated that it was possible to moderate an operator's level of engagement through a closed-loop system driven by the operator's own EEG. In addition, the system had a significant impact on behavioral, subjective, and psychophysiological correlates of workload as task load increased. The theoretical and practical implications of these results for adaptive automation are discussed.

Evaluation of an adaptive automation system using three EEG indices with a visual tracking task.

A system was evaluated for use in adaptive automation using two experiments with electroencephalogram (EEG) indices based on the beta, alpha, and theta bandwidths. Subjects performed a compensatory tracking task while their EEG was recorded and converted to one of three engagement indices: beta/(alpha + theta), beta/alpha, or 1/alpha. In experiment one, the tracking task was switched between manual and automatic modes depending on whether the subject's engagement index was increasing or decreasing under a positive or negative feedback condition. Subjects were run for three consecutive 16-min trials. In experiment two, the task was switched depending on whether the absolute level of the engagement index for the subject was above or below baseline levels. It was hypothesized that negative feedback would produce more switches between manual and automatic modes, and that the beta/(alpha + theta) index would be most effective. The results confirmed these hypotheses. Tracking performance was better under negative feedback in both experiments; also, the use of absolute levels of engagement in experiment two resulted in better performance. There were no systematic changes in these effects over three 16-min trials. The implications for the use of such systems for adaptive automation are discussed.

Effects of instruction type and boredom proneness in vigilance: implications for boredom and workload.

The present study examined the effects of instruction type and boredom proneness (BP) on vigilance performance, workload, and boredom. Subjects completed the Boredom Proneness Scale and were assigned to high and low groups based on their scores. They then monitored a VDT for critical signals. Half the subjects were instructed to detect "critical" flickers (detection emphasis), and the remaining subjects were instructed to relax but to respond to any flickers observed (relaxation emphasis). Subjects also provided pre- and postvigil ratings of workload, stress, and boredom. A performance decrement was observed for all conditions. Low-BP subjects outperformed high-BP subjects and reported less boredom. Thus the results from the present study provide evidence for the long-sought, elusive link between trait boredom and performance in vigilance. In addition, subjects who received relaxation-emphasis instructions reported lower workload, frustration, and stress for the vigil than did those receiving detection-emphasis instructions. These results are discussed in terms of a recent dynamic model of stress as it relates to sustained attention.

Sensory alternation and vigilance performance: the role of pathway inhibition.

Posner's theory of pathway inhibition leads to the expectation that stimulus heterogeneity should attenuate the event rate effect and the decrement function in sustained attention. These predictions were tested through a sensory alternation procedure in which stimulation was shuttled between the auditory and visual modalities. Subjects detected slight reductions in the duration of recurrent flashes of light or bursts of white noise at two event rates (5 and 40 events/min) during a 50-min vigil. Consistent with the model, sensory alternation eliminated the event rate effect. It did not, however, moderate the decrement function. Although pathway inhibition can account for the effects of event rate, other factors are probably responsible for the vigilance decrement.

Understanding strategic usage of 'on-the-job' reference aids.

The present set of studies examined how reference aids are collectively used to resolve problems. In addition, the present research investigated the strategies employed by documentation users as they resolved work-related questions. Subjects were given a series of questions and asked to locate the answers in a number of different types of documentation. Results of the first experiment indicated that the users' success was largely determined by their adopting an appropriate search heuristic. In the second study, the users were provided with a heuristic during training and their performance was compared with that of an expert user of the documentation. Findings from the second study revealed no difference in accuracy between the subjects and the expert; however, important qualitative strategy differences did exist between the subjects and the expert. The implications of the present results to the design of on-line computerised documentation are discussed.