Compensatory Tracking Research Articles

A comparison of factor analytic methods of obtaining cardiovascular autonomic components for the assessment of mental workload

The diagnosticity of heart rate for mental workload assessment can be improved with an autonomic space model of sympathetic and parasympathetic nervous system influences on the heart. Methods of deriving autonomic components to estimate the underlying sympathetic and parasympathetic activity needed to identify autonomic modes of control for heart period were examined. Alternative factor extraction and rotation methods were compared using data from a laboratory study that measured the electrocardiogram and impedance cardiogram simultaneously. Principal components analysis with varimax rotation was found to validly estimate the sympathetic and parasympathetic activity when computed on multiple psychophysiological measures obtained from raw EKG data. Use of the method was illustrated with single and dual mental arithmetic and secondorder compensatory manual tracking tasks. Different autonomic modes of control were found for divided attention that were not evident in heart period. Uncoupled sympathetic activation was indicated for divided attention when the mental arithmetic tasks were added to the tracking single tasks, but uncoupled parasympathetic inhibition was indicated for divided attention when the tracking tasks were added to the mental arithmetic single tasks.

Psychophysiological aspects of selective and divided attention during continuous manual tracking

Central, autonomic, and metabolic physiological measures were observed concurrently along with performance and subjective measures to compare the effects of tracking task difficulty during selective and divided attention. Eighteen dextral males performed visual compensatory manual tracking as a primary task while attending to or ignoring secondary-task auditory oddball stimuli. The difficulty of the tracking task was varied factorially by requiring participants to track with acceleration (second-order) or velocity (first-order) control and high or low bandwidth sum-of-sines disturbance. Tracking performance was affected by the difficulty manipulations but not by the attention manipulation. Event-related brain potential P300 amplitude to oddball target stimuli was sensitive to the division of attention and tracking order-of-control but not to tracking disturbance bandwidth when the oddball task was attended. Oxygen consumption, a measure of aerobic metabolism, was greater during acceleration than velocity tracking; however, cardiac measures were sensitive only to the division of attention. The results demonstrate that the attention and the task difficulty manipulations have physiologically dissociable effects that were interpreted as supporting a cognitive/energetic model of attention.

The Effects of Cigarette Smoking on Late Night Performance

This study was undertaken in order to determine the effects of an occasional late night on both smokers and non-smokers. Sixteen smokers and 16 non-smokers aged 24–45 years were enrolled onto the study. Full test batteries (comprising of Critical Flicker Fusion, CFF; Choice Reaction Time, CRT; Sternberg Short-Term Memory Task, STM; Compensatory Tracking Task, CTT; and Line Analogue Rating Scales, LARS) were completed at 18.00 h, 22.00 h, 00.00 h, 02.00 h and 08.15 h in the morning. Subjects were put to bed at 02.30 h and awakened at 07.55 h. Smokers were permitted to smoke freely throughout the trial period. CFF thresholds for the smokers remained almost constant throughout the evening, whilst those from the non-smoking control group dropped significantly from baseline (p < 0·0001). The CRT test showed that for both RRT and TRT performance remained almost constant for the non-smoking group compared with baseline, whilst the smokers' RRT improved significantly (p < 0·05) over time. TRT was quicker throughout for the smokers relative to baseline, but this did not reach significance. Performance on the MRT component was significantly quicker than baseline for the smokers at 22.00 h and 02.00 h. The RT element of the CTT task was impaired throughout the night for both groups but performance was notably better for the smoking group. Tracking error was comparable. STM gradually improved from baseline in both groups, to a greater extent in the smokers. There was a significant effect of time from the LARS data (p < 0·001) as both groups followed the pattern of the other with regards to subjective tiredness, alertness and drowsiness. When people are required to perform tasks in the late night and early morning smokers show no decrement, whilst the performance of non-smokers gets worse. © 1997 John Wiley & Sons, Ltd.

Chronopharmacokinetics and chronopharmacodynamics of dextromethamphetamine in man.

Stimulants, in particular the amphetamines, have been studied as countermeasures to fatigue induced by circadian desynchronosis and extended flight operations. To make recommendations concerning the use of dextromethamphetamine for operational tasks, its chronopharmacokinetic and chronopharmacodynamic profiles and influence on circadian rhythms as a countermeasure to performance deficits and fatigue were studied. Ten male volunteers, divided into two groups of five each, were given 30 mg/70 kg of oral dextromethamphetamine during two test sessions one week apart and were evaluated with cognitive (dichotic listening, pattern recognition, and compensatory tracking), subjective (fatigue scale), and physiologic (blood pressure) testing. Session order was counterbalanced with dextromethamphetamine administration at either 8:40 AM or 8:40 PM during session one and a crossover to the other time during session two. Subjective and cognitive testing was begun 1.5 hours before dextromethamphetamine administration and continued every half hour until 12.5 hours after administration. Blood pressure was measured immediately before behavioral testing. Serum and urine were collected at regular intervals for gas chromatography/mass spectrometer analysis of methamphetamine and one of its metabolites, amphetamine. No differences were found in the day-versus-night pharmacokinetic profile of dextromethamphetamine. Cognitive performance and subjective fatigue improved after daytime administration of dextromethamphetamine in comparison to performance before drug administration. This effect was suppressed during the circadian trough, which occurred approximately 8 hours into the night sessions (4:30 AM). No correlations were seen between serum concentration of methamphetamine and measured behavioral parameters.

Effects of a Pleasant Ambient Fragrance on Simulated Driving Performance: The Sweet Smell of … Safety?

Eighty undergraduates performed a simulated driving task that required them to keep a moving target within defined boundaries (compensatory tracking); they also performed this task while responding to randomly occurring visual stimuli (stop signs). They performed these tasks in the presence or absence of a pleasant fragrance and after receiving or not receiving a small gift. A significant Fragrance x Gift interaction indicated that performance on both tasks was significantly enhanced by pleasant fragrance but only when participants did not also receive a gift. A main effect of gift condition indicated that performance on both tasks was significantly reduced by receipt of a small gift. In a follow-up study, 5 minutes of exposure to a pleasant fragrance was found to produce significant increments in participants' positive affect and alertness. Results were interpreted as suggesting that in the absence of other sources of positive affect, exposure to a pleasant fragrance can enhance some aspects of driving p...

Event-related brain potentials and attention during simultaneous performance of two tasks.

Subjects were required to perform simultaneously a compensatory manual tracking task and an auditory discrimination task. Four behavioral measures, root-mean-square-tracking error, reaction-time, Sensitivity and Response Bias, and two physiological measures, peak amplitudes and peak latencies of the "negative difference" even-related brain potential, were used to assess the distribution of attention during task performance. Approximately 200 msec. after stimulus onset (peak latency M = 206.6 msec.), the negative difference potential's peak amplitude was more positive for tones irrelevant to the discrimination task and less positive for tones relevant to the discrimination task. This pattern of change suggests that irrelevant tones receive less attention during simultaneous performance of the tasks than during performance of the discrimination task alone. Moreover, the data suggest that the redistribution of attention while simultaneously performing the tasks directly affects processing in the sensory areas of the auditory cortex.

Dual-Task Performance as a Function of Individual Alarm Validity and Alarm System Reliability Information

Researchers and designers have investigated ways to mitigate the consequences of alarm mistrust, including using redundant information sources to ensure response consistency. Research concerning the benefit of this practice has not considered the operator's prior alarm system knowledge, or the division of attention among multiple tasks. We investigated the influence of real-time individual alarm validity information and prior alarm system reliability information on primary and alarm task responses. One hundred undergraduate students performed a continuous compensatory tracking task while responding to microcomputer-based alarms. Dependent measures included alarm response frequency, speed, accuracy, and appropriateness, and primary task tracking error. Results indicated that participants with real-time alarm validity information responded less frequently, but more appropriately than those without such information. Participants with prior access to alarm system reliability information responded more frequently than those without such information. The results are discussed as they apply to prior literature and alarm system design.

Effects of task difficulty on pilot workload

In this study, we develop a model of workload as a function of task difficulty. Experiments on compensatory tracking tasks are used to assess the task difficulties. First, second, and third order plants that are controlled under three damping frequencies, no oscillation, critically damped, and overdamped, are investigated. The task difficulty index is defined as the ratio of root means square of path error to the root means square control velocity.

Evaluation of Hand-Dominance on Manual Control of Aircraft

In the transport aircraft community the non-dominant hand control of aircraft is the norm. This historical precedence may be biasing the cockpit designs of the newer fly-by-wire aircraft which utilize a small sidestick controller rather than a wheel-column. Very little data are available to determine what effect non-dominant hand control using small throw controllers has on the pilot operator. To provide such data, a part-task simulation study was undertaken. Three different compensatory tracking tasks were performed with both left and right hand-controllers. Six right-hand dominant and three left-hand dominant subjects performed all three tasks, with both controllers. The results indicate that performance degraded and workload increased when the pilots were forced to use their non-dominant hand.

Effects of three doses of 3-indole pyruvic acid on subjective and objective measures of sleep and early morning performance

The effects of 3-indole pyruvic acid (IPA) on sleep and morning after performance were investigated in 10 volunteers with previous complaints of mild insomnia. Three doses of IPA (100, 200 and 300 mg) were compared to placebo to assess their effect on sleep, cognitive function and psychomotor performance. The psychometric battery consisted of tests of Critical Flicker Fusion, Choice Reaction Time, Short Term Memory and Compensatory Tracking. The Leeds Sleep Evaluation Questionnaire was also administered shortly after waking the morning following medication. Results show that IPA had no significant effects on any aspect of sleep architecture. However, sleep efficiency was significantly higher on night 1 when subjects had taken 200 or 300 mg IPA compared to those who had received either placebo or 100 mg IPA. No further effects were found on subsequent nights with any of the treatments. There were no morning after effects of IPA on cognitive function or psychomotor performance. The ‘first night’ effect of sleeping in an unfamiliar environment possibly caused transient insomnia in the subjects and while this effect was not mitigated by placebo or 100 mg IPA, 200 and 300 mg IPA seem to exert sufficient hypnotic effects to overcome the sleep disturbance. These results suggest that the two higher doses of IPA exert a mild hypnotic action, perhaps by relieving the stress experienced in situations that are liable to cause transient insomnia.

Comparative behavioural toxicity of the selective serotonin reuptake inhibitors.

The psychopharmacological profiles of several selective serotonin reuptake inhibitors (SSRIs) were compared and their behavioural toxicity contrasted both to placebo and the tricyclic antidepressants dothiepin and amitriptyline. On measures of central nervous system arousal (critical flicker fusion), psychomotor speed (choice reaction time), skilled performance (compensatory tracking) and subjective ratings of sedation (line analogue rating scales), the tricyclic compounds clearly impaired performance and led to higher ratings of sedation. While the SSRIs were generally clear of these gross effects, there were quantifiable differences between the compounds, seen mainly as an increase in central nervous system arousal. It remains to be established whether these minor differences have any clinical relevance.

Is Voluntary Control of Breathing Impaired in Patients with Chronic Obstructive Pulmonary Disease?

1. To assess whether voluntary control of breathing is impaired in patients with chronic obstructive pulmonary disease, a group of such patients performed a tracking task, requiring volitional control of respiratory muscles. 2. Eight patients (mean age 60 years; mean ratio of forced expiratory volume in 1 s to forced vital capacity = 31%) took part in the study. Five of the seven patients in whom blood gas measurements were made were mildly hypoxaemic (PaO2 = 53-71 mmHg), and one of these was hypercapnic (PaCO2 = 55 mmHg). Each subject performed a compensatory ventilatory tracking task using a tracking system which comprised a fixed target displayed on a monitor screen and a cursor moving in a line bisecting the target. The position of the cursor was perturbed by a forcing function and patients were required to keep the cursor on the target by breathing in and out of a spirometer. 3. To allow for any non-specific deficiency in motor control, patients performed a similar manual tracking task, using their dominant arm to move a joystick. As a control group, 11 healthy subjects (mean age 58 years; mean ratio of forced expiratory volume in 1 s to forced vital capacity = 77%) underwent an identical experimental protocol. 4. Motor control performances were measured in terms of the error between the target position and the subject's positioning of the cursor. Indices of performance were the root mean square of the error and the averages of the zero errors (i.e. end expiration/arm movement towards the trunk) and the peak errors (i.e. end inspiration/arm movement from the trunk).(ABSTRACT TRUNCATED AT 250 WORDS)

Primate performance decrements following acute soman exposure: Failure of chemical countermeasures

Three experiments are reported: 1) a feasibility study on using laboratory primates repeatedly in behavioral toxicity studies of organophosphate (OP) agents or of chemical countermeasures against OPs; 2) a study of the efficacy of pyridostigmine pretreatment and 2-PAM therapy; and 3) a study to determine the effects of these treatments on soman-induced cholinesterase (ChE) inhibition and its recovery. In rhesus monkeys, three repeated acute low-dose (2.1 to 2.8 μg/kg) soman exposures, separated by intervals > 5 weeks, did not change baseline compensatory tracking performance or the soman ED 50. Atropine therapy (97 μg/kg) alone had no effect on soman ED 50. Addition of pyridostigmine pretreatment (150 μg/kg) and 2-PAM therapy (17 mg/kg) to atropine therapy increased the soman ED 50 for a performance decrement from 2.27 μg/kg to 2.58 μg/kg, an insignificant protective effect. At the soman ED 50 for behavioral decrements, pyridostigmine pretreatment increased the inhibition of serum ChE observed immediately after soman exposure, but reduced the extent of permanent inhibition. The 2-PAM therapy reduced serum ChE inhibition from about 80% to less than 70%. These effects on the time course of ChE inhibition following soman exposure appear to combine additively. These chemical countermeasures do not prevent soman-induced performance decrements, even though they are effective in protecting lives after much higher doses. The soman doses used produce only small, transient performance decrements; animals so exposed can, thus, be used repeatedly in such studies.

Cumulative Effects of +Gz on Cognitive Performance

A study is described which examines the interaction of two of the most salient stressors found in the tactical aviation cockpit: 1) highly demanding decision-making tasks, and 2) intermittent periods of high G. Addressing this issue is critical because: 1) it is probable that physiological stressors such as G may have serious ramifications on pilots' abilities to perform complex cognitive tasks; 2) there may be different impacts of G on different types of cognitive tasks, and the impact of these deficits may be correlated with the cumulative amount of time a pilot has spent under G; 3) it is not clear that donning protective gear will have an effect on cognitive task performance; and 4) there are no data to suggest how long cognitive decrements due to exposure to physiological stressors will last. A general approach is described for evaluating the cumulative effects of physiological stressors (e.g., G) on cognitive task performance in a within-subjects experimental design. A PC-based task suite was used incorporating three concurrently performed tasks: a compensatory tracking task, a resource management task, and a system monitoring task. Results indicated that performance across the experimental conditions was highly variable. Preliminary results demonstrated that: 1) even low-level increases in G can be disruptive to subject performance, 2) there are cumulative decrements in task performance during G, and 3) if stable performance on tasks is required, training for complex task performance must take place in the presence of salient physiological stressors.

Behavioral toxicity of anticholinesterases in primates: Effects of daily repeated soman exposure

The effects of repeated daily exposure to soman, an organophosphate nerve agent, on the performance of a well-learned, compensatory tracking task were tested in rhesus monkeys. The ED 50 daily exposure required to produce a performance decrement on or before the fifth daily exposure (0.97 μg/kg) was about 40% of the acute dose required to produce a similar performance decrement. After repeated, low-dose exposures, performance decrements appeared when serum cholines-terase (ChE) activity was inhibited 85–90%. Acute exposures that produced similar performance effects were associated with lower levels of ChE inhibition (65–70%), suggesting that repeated daily exposure may lead to the development of a tolerance (physiological or behavioral) to low levels of ChE activity.

Acute Behavioral Toxicity of Pyridostigmine or Soman in Primates

Effects of a peripherally active carbamate (pyridostigmine bromide) and a centrally active organophosphate (OP) nerve agent (soman) on performance by rhesus monkeys of a compensatory tracking (primate equilibrium platform, or PEP) task were measured using a balanced Latin-square design to determine the ED50 for pyridostigmine (0.66 mg/kg) and the up-and-down (titration) method to determine the ED50 for soman (2.50 μg/kg). We concluded that the PEP performance model is a sensitive and reliable indicator of anticholinesterase (anti-ChE) behavioral toxicity. We also found that soman, an irreversible inhibitor of acetylcholinesterase (AChE), is more than 100 times more behaviorally disruptive than the reversible peripheral inhibitor pyridostigmine, as indicated by the difference in ED50 doses expressed in molar terms. Soman′s behavioral toxicity is severe at levels of serum cholinesterase inhibition (70-80%) at which pyridostigmine does not significantly affect performance. As a prophylactic treatment for OP agent poisoning, pyridostigmine has a substantial safety factor, since behavioral toxicity becomes significant only at approximately four times the proposed therapeutic dose.

The coordination of compensatory tracking and anticipatory timing tasks

Two experiments investigated the presence of a coordination factor in a task consisting of compensatory tracking and anticipatory timing components. The task (Intercept task) resembles a computer game in which a rocket must be aimed and fired to shoot an incoming missile. The studies were designed to determine if a coordinating ability exists above and beyond the abilities needed to perform the component tasks alone. We also investigated the nature of coordination abilities through correlations with other types of coordination tasks and measures of intelligence. Is coordination a general cognitive ability that contributes to performance in a wide range of coordination tasks, or is coordination ability task specific? Multiple regression analyses indicated the existence of a coordination ability in the Intercept task. This coordination ability, however, was shown to be unrelated to the coordination of visual and linguistic processing and to psychometric measures of intelligence as assessed by the Armed Services Vocational Aptitude Battery (ASVAB). Coordination of visual and linguistic processing correlated with a component of the ASVAB measuring perceptual speed. We conclude that, although the ability to integrate separate components of a complex task draws on a coordination ability, this ability is domain specific and thus varies depending on the nature of the component tasks.

Human Performance in Actuating Switches During Tracking

The objectives of this study were to develop an engineering model of pilotage performance times in actuating switches and to test the feasibility of its use in task time-line analysis. A low-fidelity environment was simulated. Compensatory tracking was used to approximate the concurrent task of aircraft control corrections to turbulence during straight-level flight. Variables that affected time and tracking performance were identified for use in predicting performance. Several desired features of switch-actuation performance times were investigated for prediction purposes. Our experimental results confirmed that the most needed and desired features existed or were well approximated for estimating performance times in these analyses for use during early stages of aircraft design. The engineering model should offer improved efficiency to task time-line analysis. Tracking errors were analyzed to estimate the vision and attention requirements of the variations in switch-actuation tasks.

Divided attention task performance and subjective effects following alcohol and placebo: differences between women with and without a family history of alcoholism

Women with (FHP) and without (FHN) family histories of alcoholism received either 0.56 g/kg alcohol or an isocaloric placebo in a repeated measures group design. Subjects performed a divided attention task and gave subjective ratings of 12 alcohol effects over a 3-h interval. After comparable doses of alcohol, 7 FHP and 10 FHN women had comparable ascending (blood alcohol levels) BALs. BALs peaked earlier for FHP women and then steadily declined. FHP women had a concomitant increase in visual search response times 30 min after alcohol. In contrast, scores on a simultaneously presented compensatory tracking task were virtually identical for the 7 FHP and 10 FHN women after alcohol and for the 8 FHP and 10 FHN women after placebo. After alcohol the FHP and FHN women had 7 out of 12 significantly different subjective ratings of alcohol responses. FHP women had lower subjective responses to alcohol and lower BALs, but their subjective responses were more strongly correlated with BALs. Our findings for women studied in a group design confirm the lower magnitude of subjective responses reported for pair-matched FHP men following comparable doses of alcohol in within-subjects and between-subjects designs in other laboratories.

Perceived Fairness of Drug Screening and Performance Testing as Methods for Detecting Performance Impairment

Drug abuse is prevalent and impacts all aspects of society, including the workplace. Testing for impairment due to alcohol or other drug use has become commonplace in organizational settings. Despite potential problems with accuracy, the most commonly used method of screening is urinalysis. As drug testing becomes more common, concern over employees' rights to privacy and fairness of drug testing has also increased. Performance testing has been proposed as a solution to the problems associated with urinalysis, for jobs where eye-hand coordination is critical to job performance. Performance testing is based on the compensatory tracking task and involves correcting for the unpredictable movement of a visual stimulus on a computer screen. Although research suggests that urinalysis testing is perceived as fair in some situations (e.g., where need is high such as in safety-sensitive jobs), no research has been conducted which examines the perceived fairness of performance testing. The purpose of the current research was to examine the effects of type of testing (urinalysis versus performance testing) and need for testing (high versus low accident history) on perceived fairness and invasion of privacy. In addition, the effects of fairness and invasiveness on the willingness to apply for a job in the company and acceptance of the screening policy was examined. One-hundred adults participated in the study. Results indicated that urinalysis screening was perceived as more fair than performance testing. No effects of need (accident rate) were obtained for either fairness or invasion of privacy. Multiple regression analysis indicated that both fairness perceptions and invasion of privacy predicted willingness to apply for a job and acceptance of the policy. Implications of the results and suggestions for future research are discussed.