Physiological indices of workload in a simulated flight task

The sensitivity of physiological measures to evaluate workload was investigated in a simulated flight task. Heart rate, blood pressure (from beat to beat), respiration and eye blinks were recorded in 14 subjects while they performed a complex task in a flight simulator. Workload was manipulated by introducing an additional task and by varying the task difficulty of segments of the flight scenarios. Heart rate and blood pressure were both affected by the different levels of task difficulty. Heart-rate variability was found to be confounded by respiration. Slow respiratory activity contributed considerably to heart rate variability, especially after periods of high workload (for example, after landing). The gain between blood-pressure and heart-rate variability (modulus) was sensitive to mental effort and was not influences by respiration. Eye blinks, in particular the duration, were specifically affected by the visual demands of the task and not by the workload in general. When subjects had to process visual information, the number and duration of blinks decreased.     

Electrophysiological, behavioral, and subjective indexes of workload when performing multiple tasks: manipulations of task difficulty and training

This study examined whether alpha event-related desynchronization (ERD) and theta event-related synchronization (ERS) could successfully measure changes in cognitive workload and training while an operator was engaged in a continuous, interactive, control task(s). Alpha 1 (8-10 Hz) ERD, alpha 2 (10-12 Hz) ERD, and theta (3-7 Hz) ERS were determined for a communications event that occurred during multiple task workload conditions or as a single task. Other measures (alpha and theta EEG power, heart rate, respiration, eye blinks, behavioral performance, and subjective workload ratings) were also evaluated. Results showed that alpha 2 EEG, heart rate, behavioral, and subjective measures were sensitive to changes in workload in the multiple tasks. In addition, eye blink rate and behavioral measures were sensitive to training. Alpha ERD and theta ERS were not sensitive to workload and training in our interactive, multiple task environment. However, they were effective indexes of cognitive/behavioral demands within an interactive single task.     

Context effects in subjective mental workload ratings

The impact of performance context on subjective mental workload ratings was assessed with the Subjective Workload Assessment Technique (SWAT) and the NASA Task Load Index (TLX). In Experiment 1, a strong context effect was demonstrated. A low range of task difficulty produced considerably higher ratings on a common set of difficulty levels than did a high range of task difficulty. In Experiment 2, increasing the participants' range of experiences during practice eliminated the context effect. We recommend that methods for standardizing context, such as providing experience with the complete difficulty range, be developed for subjective mental workload evaluations. Actual or potential applications of this research include providing methodologies for controlling context effects in practical assessments of mental workload to increase the validity of subjective measures.     

Integrating laboratory and field study for improving selection: Development of a battery for predicting air traffic controller success.

Describes an example of combining laboratory- and field-based study to develop a selection battery for field implementation. The procedure provides advantages in comparison with sole use of field-based experimentation, namely, greater control over examinee samples, collection of construct validity data, and fewer field demands for cross-validation. Two experiments were conducted that converge on development of a test battery for selection of air traffic controllers (ATCs). The lab study (N?=?112) used an ATC simulator (terminal radar approach control, or TRACON) for initial development and evaluation of the selection battery. The field study of 206 Federal Aviation Administration ATC trainees provided cross-validation data as a precursor to implementation of the battery. Implications for developing ability-based and self-efficacy-based selection measures for complex job performance are discussed, as are general issues for new selection research and application. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factors influencing mental workload indexes

Several findings of the author's own mental workload research are reviewed. Especially, factors, except task demand, influencing mental workload indexes are discussed. First, an experiment using the National Aeronautics and Space Administration Task Load Index (NASA TLX) is reviewed and the effects of a prior task load on a subsequent subjective workload are described. In a physiological measures section, the low reliability of the heart rate variability (HRV) parameters when the subjects' respiration pattern are highly irregular, and the existence of low sweat respondent, although perspiration seems to be sensitive to the workload, are indicated. Furthermore, results of the task specific physiological responses and of a HRV parameter affected by the individual characteristics, like type A behavior pattern, are shown. Discrepancy between autonomic nervous system activity measures may be solvable by introducing a new concept of autonomic space (synergism of sympathetic and parasympathetic nervous system). Finally, the need for strategies of data management concerning the individual differences is emphasized.     

Genetic epidemiology of breast and ovarian cancers

Most civilian and military air traffic control facilities in the United States use rapid rotation shift schedules. These schedules have generally been chosen for social reasons. Safety concerns have been raised because the air traffic controllers (ATCs) often carry an acute sleep debt onto the night-shift where they have little active work to do as they sit in the dark at the nadir of their circadian rhythms. This paper reviews advancing and delaying rapid shiftwork schedules, ATC workload factors as they relate to error rates and safety, and potential countermeasures. Recent studies indicate that ATC performance declines on the night-shift and that ATCs may be falling asleep while on-duty. There is indirect evidence that ATC error rates are highest on the night-shift. There are only limited studies which have evaluated potential countermeasures. The operational significance of the problems associated with ATC shiftwork is not yet clear. Further study is needed.     

When expertise reduces age differences in performance.

Examined whether aviation expertise reduces age differences in a laboratory task that was similar to routine air traffic control (ATC) communication. In Exp 1, older (mean age 66.6 yrs) and younger (mean age 29.0 yrs) pilots and age-matched nonpilots read typical ATC messages (e.g., commands to change aircraft heading). After each message, they read back (repeated) the commands, which is a routine ATC procedure requiring short-term memory. Ss also performed less domain-relevant tasks. Expertise eliminated age differences in repeating heading commands but did not reduce age differences for the less relevant tasks. In Exp 2, expertise reduced but did not eliminate age differences in repeating heading commands from spoken messages. Results suggest that expertise compensates age declines in resources when the task is highly domain relevant. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive and noncognitive determinants and consequences of complex skill acquisition.

Integration of multiple perspectives on the determinants of individual differences in skill acquisition is provided by examination of a wide array of predictors: ability (spatial, verbal, mathematical, and perceptual speed), personality (neuroticism, extroversion, openness, conscientiousness, and agreeableness), vocational interests (realistic and investigative), self-estimates of ability, self-concept, motivational skills, and task-specific self-efficacy. Ninety-three trainees were studied over the course of 15 hr (across 2 weeks) of skill acquisition practice on a complex, air traffic controller simulation task (Terminal Radar Approach Controller; TRACON; Wesson International, Austin, TX). Across task practice, measures of self-efficacy, and negative and positive motivational thought occurrence were collected to examine prediction of later performance and communality with pretask measures, Results demonstrate independent and interactive influences of ability tests and self-report measures in predicting training task performance. Implications for the selection process are discussed in terms of communalities observed in the predictor space. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term effects of occupational stressors on daily mood and health complaints.

Related daily changes in 2 job conditions, workload and social interaction with co-workers and supervisors, to daily mood and health complaints. 52 air-traffic controllers (ATCs) completed measures of subjective well-being and perceived job conditions on 3 consecutive days; objective indicators of daily workload (air traffic volume and visibility at the airport) were also obtained. The results indicate that increases in job stressors are associated with a same-day deterioration in physical and psychological well-being. On days in which workload was perceived to be high, ATCs reported more health complaints and moods that were more negative and less positive. On days in which there was greater air traffic volume (objectively measured), ATCs reported moods that were more negative. On days in which interactions with co-workers and supervisors were described as more distressing, ATCs reported moods that were more negative and less positive. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heart period variability and respiratory changes associated with physical and mental load: non-linear analysis

In the investigation of heart rate and heart rate variability, the discrimination between mental workload, physical activity and respiration is known to be methodologically difficult. At most, heart rate variability measures are more likely to be coarse-grained measures with variability confounded by heart rate. Moreover, the spectral analysis of heart rate variability shows broad-band frequency characteristics, pointing towards non-stationarity or non-linearity. From this it is suggested to focus on non-linear dynamic analyses that are variance-insensitive. The experimental section of the paper focuses on the estimation of two non-linear measures for both heartbeat dynamics and respiration, the correlation dimension indicating complexity and the Lyapunov exponents indicating predictability. The results indicate that the complexity of heart dynamics is related to the type of task and that the predictability of heart dynamics is related to the amount of load.     

Stimulus complexity and the EEG: Differential effects of the number and the variety of display elements.

Contends that previous findings supporting D. Berlyne's suggestion, that stimulus complexity affects the EEG of an O (a) confounded different dimensions of stimulus complexity, and (b) failed to demonstrate that perceived complexity varied in accordance with the independent variable. Results of the present 5 experiments with a total of 33 undergraduates indicate that (a) both the number and variety of elements in a visual display affected judgments of complexity, (b) alpha activity decreased as number of elements increased, and (c) evidence for the effects of variety was inconclusive. It is concluded that the number and variety of elements are 2 dimensions of stimulus complexity which may have differential effects on EEG. (French summary) (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction to Nunes and Kramer (2009).

Reports an error in "Experience-based mitigation of age-related performance declines: Evidence from air traffic control" by Ashley Nunes and Arthur F. Kramer (Journal of Experimental Psychology: Applied, 2009[Mar], Vol 15[1], 12-24). In the article, the URL published for the supplemental material was incorrect. The correct URL is http://dx.doi.org/10.1037/a0014947.supp (The following abstract of the original article appeared in record 2009-03685-002.) Previous research has found age-related deficits in a variety of cognitive processes. However, some studies have demonstrated age-related sparing on tasks where individuals have substantial experience, often attained over many decades. Here, the authors examined whether decades of experience in a fast-paced demanding profession, air traffic control (ATC), would enable older controllers to perform at high levels of proficiency. The authors also investigated whether older controllers would show diminished age-related decrements on domain-relevant cognitive abilities. Both young and old controllers and noncontrollers performed a battery of cognitive and ATC tasks. Results indicate that although high levels of experience can reduce the magnitude of age-related decline on the component processes that underlie complex task performance, this sparing is limited in scope. More important, however, the authors observed experience-based sparing on simulated ATC tasks, with the sparing being most evident on the more complex air traffic control tasks. These results suggest that given substantial experience, older adults may be quite capable of performing at high levels of proficiency on fast-paced demanding real-world tasks. The implications of these findings for global skilled labor shortages are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concurrent response-selection processes in dual-task performance: Evidence for adaptive executive control of task scheduling.

This article reports 4 experiments that used the psychological refractory period procedure to characterize how people perform multiple tasks concurrently. For each experiment, a primary choice-reaction task was paired with a secondary choice-reaction task that had two levels of response-selection difficulty. Experiments 1 and 2 varied secondary-task response-selection difficulty by manipulating the number of stimulus-response (S-R) pairs. The effect of this factor on secondary-task reaction times (M) decreased reliably as the stimulus onset asynchrony (SOA) decreased. Experiments 3 and 4 varied secondary-task response-selection difficulty by manipulating S-R compatibility. Again, the effect of this factor on secondary-task M decreased reliably as SOA decreased. These results raise doubts about the existence of an immutable structural response-selection bottleneck and suggest that response selection for 2 concurrent tasks may overlap temporally. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Advances and controversies in the diagnosis and management of medullary thyroid carcinoma

In tasks requiring sustained attention, human alertness varies on a minute time scale. This can have serious consequences in occupations ranging from air traffic control to monitoring of nuclear power plants. Changes in the electroencephalographic (EEG) power spectrum accompany these fluctuations in the level of alertness, as assessed by measuring simultaneous changes in EEG and performance on an auditory monitoring task. By combining power spectrum estimation, principal component analysis and artificial neural networks, we show that continuous, accurate, noninvasive, and near real-time estimation of an operator's global level of alertness is feasible using EEG measures recorded from as few as two central scalp sites. This demonstration could lead to a practical system for noninvasive monitoring of the cognitive state of human operators in attention-critical settings.     

Modulation of the attentional blink by differential resource allocation.

When one masked target (T2) follows another (T1) in close temporal proximity, identification accuracy of the second target is reduced for a period referred to as the attentional blink. Analysis of the attentional blink literature suggests that increasing the difficulty of T1 processing increases the magnitude of the blink. In a previous study that eliminated several untoward features of the typical attentional blink design (e.g., task switching, location switching, and stream contribution), we found no effect on blink magnitude when three levels of T1 difficulty (manipulated in a data-limited manner) were randomly intermixed. Here, when we repeated the previous study, with 20 college students, using a blocked manipulation of T1 difficulty, which is characteristic of the literature, a significant positive relation between T1 difficulty and blink magnitude was found. Resource allocation put in place to encode T1 in advance of a dual-target trial thus seems to be the critical factor in mediating this relation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experience-based mitigation of age-related performance declines: Evidence from air traffic control.

[Correction Notice: An erratum for this article was reported in Vol 15(2) of Journal of Experimental Psychology: Applied (see record 2009-09189-003). In the article, the URL published for the supplemental material was incorrect. The correct URL is http://dx.doi.org/10.1037/a0014947.supp] Previous research has found age-related deficits in a variety of cognitive processes. However, some studies have demonstrated age-related sparing on tasks where individuals have substantial experience, often attained over many decades. Here, the authors examined whether decades of experience in a fast-paced demanding profession, air traffic control (ATC), would enable older controllers to perform at high levels of proficiency. The authors also investigated whether older controllers would show diminished age-related decrements on domain-relevant cognitive abilities. Both young and old controllers and noncontrollers performed a battery of cognitive and ATC tasks. Results indicate that although high levels of experience can reduce the magnitude of age-related decline on the component processes that underlie complex task performance, this sparing is limited in scope. More important, however, the authors observed experience-based sparing on simulated ATC tasks, with the sparing being most evident on the more complex air traffic control tasks. These results suggest that given substantial experience, older adults may be quite capable of performing at high levels of proficiency on fast-paced demanding real-world tasks. The implications of these findings for global skilled labor shortages are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition potential: sensitivity to visual field stimulated

The recognition potential (RP) was distinguished from P3 and eye blink responses by its sensitivity to visual area stimulated. Images were flashed in upper and lower hemifields. Current source density profiles were computed, using 16 midline scalp electrodes. For P3 and eye blink profiles, the hemifield stimulated was not a significant factor. For the recognition potential, upper and lower field stimulation produced radically different profiles. An improved recognition potential signal was obtained by a new mathematical procedure. It used the difference in sensitivity to visual area stimulated to reject P3 and eye blink responses.     

The occurrence of human intestinal parasites in Finland

We describe an apparatus measuring the cornealreflex stimulated pneumatically. The flow of preassurised air in the range of 0.1-1.5 bar is controlled by an electromagnetic switch. The time the valve is open, is variable. The air flow is directed to the cornea of the eye. The blink reflex is recorded by means of the surface electromyogramm and displayed on the screen of a storage scope. The device allows a clean, reproducable and simple measurement of the cornealreflex.     

Heart rate and workload variations in actual and simulated flight

The monitoring of heart rate in aviation research provides a global index of pilot workload. Heart rate variability is a promising measure but more complex to assess and therefore less often used, especially in dynamic task environments. The application of spectral analysis techniques of heart rate for workload assessment in aviation is illustrated and discussed. Ideally, workload assessment includes real-time or continuous measures to reveal variations in workload as pilots accomplish their tasks. Four studies are discussed that used heart rate measures for the assessment of: (1) training effectiveness; (2) stress of flight instruction; (3) simulator realism; and (4) flight task difficulty. Results indicate that cardiovascular measures are well suited to index different mental states of pilots as well as their dynamic responses to variations in workload.