Frederick G. Freeman

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 subjects 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.

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 operators level of engagement through a closed-loop system driven by the operators 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.

The effect of interstimulation interval on the assessment and stability of kindled seizure thresholds.

Two experiments were conducted to investigate the importance of the interstimulus interval (ISI) in the assessment of kindled seizure thresholds using an ascending method of limits. A third experiment examined the effect of varying the interval between successive threshold tests on threshold stability. No differences in afterdischarge (AD) or motor seizure (MS) threshold were observed when the ISI was either five minutes or 48 hours. However, a 30 second ISI yielded significantly higher AD and MS thresholds and shorter seizure duration compared to 1, 3, or 5 minute ISIs. AD and MS thresholds were found to be relatively stable over five successive tests when the inter-test interval was 48 hours. An inter-test interval of 24 hours, however, yielded progressively higher thresholds over the five tests.

Effects of a psychophysiological system for adaptive automation on performance, workload, and the event-related potential P300 component

The present study examined the effects of an electroencephalographic- (EEG-) based system for adaptive automation on tracking performance and workload. In addition, event-related potentials (ERPs) to a secondary task were derived to determine whether they would provide an additional degree of workload specificity. Participants were run in an adaptive automation condition, in which the system switched between manual and automatic task modes based on the value of each individuals own EEG engagement index; a yoked control condition; or another control group, in which task mode switches followed a random pattern. Adaptive automation improved performance and resulted in lower levels of workload. Further, the P300 component of the ERP paralleled the sensitivity to task demands of the performance and subjective measures across conditions. These results indicate that it is possible to improve performance with a psychophysiological adaptive automation system and that ERPs may provide an alternative means for distinguishing among levels of cognitive task demand in such systems. Actual or potential applications of this research include improved methods for assessing operator workload and performance.

A brain-based system for adaptive automation

Adaptive automation refers to technology that can change its mode of operation dynamically. Further, both the technology and the operator can initiate changes in the level or mode of automation. One of the important issues surrounding this technology concerns the method for initiating changes in the state of automation. The present paper considers the potential of using brain activity to drive an adaptive automation system. Relevant research on EEG is presented followed by a review of several experiments in which EEG is used to trigger changes among system modes in an adaptive automation system. The system moderates operator task load based upon an index derived from a ratio of EEG power bands. The research shows that it may be feasible to build an adaptive automation system and use this index of brain activity to drive the system. The paper concludes with a discussion of several issues that still need to be addressed before this approach can move beyond the laboratory.

Comparison of a brain-based adaptive system and a manual adaptable system for invoking automation

Objective: Two experiments are presented examining adaptive and adaptable methods for invoking automation. Background: Empirical investigations of adaptive automation have focused on methods used to invoke automation or on automation-related performance implications. However, no research has addressed whether performance benefits associated with brain-based systems exceed those in which users have control over task allocations. Method: Participants performed monitoring and resource management tasks as well as a tracking task that shifted between automatic and manual modes. In the first experiment, participants worked with an adaptive system that used their electroencephalographic signals to switch the tracking task between automatic and manual modes. Participants were also divided between high-and low-reliability conditions for the system-monitoring task as well as high- and low-complacency potential. For the second experiment, participants operated an adaptable system that gave them manual control over task allocations. Results: Results indicated increased situation awareness (SA) of gauge instrument settings for individuals high in complacency potential using the adaptive system. In addition, participants who had control over automation performed more poorly on the resource management task and reported higher levels of workload. A comparison between systems also revealed enhanced SA of gauge instrument settings and decreased workload in the adaptive condition. Conclusion: The present results suggest that brain-based adaptive automation systems may enhance perceptual level SA while reducing mental workload relative to systems requiring user-initiated control. Application: Potential applications include automated systems for which operator monitoring performance and high-workload conditions are of concern.

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: β/(α + θ) and β/θ. 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.

Discrimination learning and stimulus generalization in rats with hippocampal lesions

Abstract Rats with hippocampal lesions and sham operated control animals were trained on a go-no-go tone discrimination. For half of the animals of each group the tone was the positive stimulus while for the other half the tone was negative. The hippocampal tone negative group took the greatest number of days to learn the task. Tone generalization tests administered the day after the learning criterion was reached did not yield any differences in either excitatory or inhibitory stimulus control between the hippocampal and sham animals.

Phencyclidine raises kindled seizure thresholds

Phencyclidine (PCP) has been reported to have both anesthetic and seizure-inducing properties. In the present experiment the effect of PCP on previously established seizures, kindled in the amygdala, was examined, using rats as subjects. In a repeated measures design three doses of PCP (1, 2 and 5 mg/kg) were compared with a saline control condition. The high dose of PCP was found to significantly increase seizural afterdischarge thresholds, while not affecting seizure durations.

The effects of reinforcement delay and hippocampal lesions on the acquisition of a choice response

This study examined the effect of lesions of the hippocampus in rats and delay of reinforcement (0 or 10 sec) on the acquisition of a spatial response in a Y-maze. The results indicated that the acquisition of the response is markedly retarded in animals with lesions of the hippocampus when a 10-sec reinforcement delay is used. The results are taken to support the notion of increased distractibility in the lesioned animals.