Statler, Irving C. — Page 2 | Engineering Papers

NASA NTRS1994

Analysis of Crew Fatigue in AIA Guantanamo Bay Aviation Accident

Flight operations can engender fatigue, which can affect flight crew performance, vigilance, and mood. The National Transportation Safety Board (NTSB) requested the NASA Fatigue Countermeasures Program to analyze crew fatigue factors in an aviation accident that occurred at Guantanamo Bay, Cuba. There are specific fatigue factors that can be considered in such investigations: cumulative sleep loss, continuous hours of wakefulness prior to the incident or accident, and the time of day at which the accident occurred. Data from the NTSB Human Performance Investigator's Factual Report, the Operations Group Chairman's Factual Report, and the Flight 808 Crew Statements were analyzed, using conservative estimates and averages to reconcile discrepancies among the sources. Analysis of these data determined the following: the entire crew displayed cumulative sleep loss, operated during an extended period of continuous wakefulness, and obtained sleep at times in opposition to the circadian disposition for sleep, and that the accident occurred in the afternoon window of physiological sleepiness. In addition to these findings, evidence that fatigue affected performance was suggested by the cockpit voice recorder (CVR) transcript as well as in the captain's testimony. Examples from the CVR showed degraded decision-making skills, fixation, and slowed responses, all of which can be affected by fatigue; also, the captain testified to feeling "lethargic and indifferent" just prior to the accident. Therefore, the sleep/wake history data supports the hypothesis that fatigue was a factor that affected crewmembers' performance. Furthermore, the examples from the CVR and the captain's testimony support the hypothesis that the fatigue had an impact on specific actions involved in the occurrence of the accident.

Rosekind, Mark R.↗

NASA NTRS1994

Visibility of DCT Basis Functions: Effects of Contrast Masking

Current strategies for compressing images neglect to accommodate certain aspects of the human visual system. One such neglected aspect is contrast masking. Here we provide measurements of contrast masking within the framework of the discrete cosine transform (DCT). We describe how to optimize DCT-based compression with respect to contrast masking.

Soloman, Joshua A.↗

NASA NTRS1994

Visibility of DCT Quantization Error: Effects of Display Resolution

As part of a program of research to understand the visibility of DCT quantization errors and thereby design optimal quantizers, we measured visibility of DCT quantization error as a function of display resolution in pixels/degree. Visibilities are consistent with a model incorporating effects of block size and spatial pooling.

Watson, Andrew B.↗

NASA NTRS1994

A Modular, Portable Model of Image Fidelity

There is a persistent need for a trustworthy model of perceptual image fidelity, especially in applications such as image compression and display design. A fidelity model provides a measure of the visual discriminability of two images. Ahumada has previously shown that the existing fidelity models may be categorized according to their inclusion of various canonical properties, such as a contrast sensitivity function, spatial frequency channels, etc. This suggests that research would be aided by the availability of a modular model, in which these components could be easily inserted or removed. A further impediment to research in this area has been that most models are written in low-level languages and are consequently large, non-portable, and difficult to understand, modify, and maintain. We therefore believe research would also be aided by models written in high-level languages. To serve both of these purposes, and to honor our conference host for his lifetime dedication to the problem of image quality. Global brightness and its effect on perceptual image quality. We offer a modular model written in the high-level language Mathematica. We will demonstrate this model and show how it may be modified.

Watson, Andrew B.↗

NASA NTRS1994

Distance Perception of Stereoscopically Presented Virtual Objects Optically Superimposed on Physical Objects by a Head-Mounted See-Through Display

The influence of physically presented background stimuli on the perceived depth of optically overlaid, stereoscopic virtual images has been studied using headmounted stereoscopic, virtual image displays. These displays allow presentation of physically unrealizable stimulus combinations. Positioning of an opaque physical object either at the initial perceived depth of the virtual image or at a position substantially in front of the virtual image, causes the virtual image to perceptually move closer to the observer. In the case of objects positioned substantially in front of the virtual image, subjects often perceive the opaque object to become transparent. Evidence is presented that the apparent change of position caused by interposition of the physical object is not due to occlusion cues. According, it may have an alternative cause such as variation in the binocular vengeance position of the eyes caused by introduction of the physical object. This effect may complicate design of overlaid virtual image displays for near objects and appears to be related to the relative conspicuousness of the overlaid virtual image and the background. Consequently, it may be related to earlier analyses of John Foley which modeled open-loop pointing errors to stereoscopically presented points of light in terms of errors in determination of a reference point for interpretation of observed retinal disparities. Implications for the design of see-through displays for manufacturing will be discussed.

Ellis, Stephen R.↗

NASA NTRS1994

Alertness Management In Flight Operations: A NASA Education and Training Module

Since 1980, the NASA Ames Fatigue Countermeasures Program has been conducting research on sleep, circadian rhythms, and fatigue in a variety of flight operations 1. An original goal of the program was to return the scientific and operational knowledge to the aviation industry. To meet this goal, the NASA Ames Fatigue Countermeasures Program has created an Education and Training Module entitled, "Strategies for Alertness Management in Flight Operations." The Module was designed to meet three objectives: 1) explain the current state of knowledge about the physiological mechanisms underlying fatigue, 2) demonstrate how this knowledge can be applied to improve flight crew sleep, performance, and alertness, and 3) offer countermeasure recommendations. The Module is composed of two components: 1) a 60-minute live presentation provided by a knowledgeable individual and 2) a NASA/FAA Technical Memorandum (TM) that contains the presentation materials and appendices with complementary information. The TM is provided to all individuals attending the live presentation. The Module content is divided into three parts: 1) basic information on sleep, sleepiness, circadian rhythms, fatigue, and how flight operations affect these physiological factors, 2) common misconceptions about sleep, sleepiness, and fatigue, and 3) alertness management strategies. The Module is intended for pilots, management personnel, schedulers, flight attendants, and the many other individuals involved in the aviation system.

Rosekind, Mark R.↗

NASA NTRS1994

In Search of an Optoretinogram

A sensitive apparatus was constructed to measure the infrared reflectance of human retinas in vivo. Changes in the light scattering properties of rod outer segments have been observed both in excised retinas and photoreceptor suspensions, motivating the present work. Unlike results of vitro studies, no visually evoked changes were observed, despite a very low noise level. Methods for improving the technique using modem developments in CCD cameras are discussed.

Mulligan, Jeffrey B.↗

NASA NTRS1994

Additional Twists on A Continuous Barber - Pole Illusion

The barber pole illusion is a well-known example of how the perceived direction of motion of an inherently ambiguous one-dimensional pattern is influenced by the shape of the area covered by the pattern. Similar effects may be observed for a stimulus which is restricted to a narrow band of spatial frequencies: when a sinusoidal grating is drifted behind a two-dimensional Gaussian contrast window having unequal standard deviations, the direction of perceived motion is biased in the direction of the major axis of the elliptical window (Mulligan, ARVO 1991). We have extended these results to provide insight into possible mechanisms responsible for the effect.

Mulligan, J. B.↗

NASA NTRS1994

Shared Problem Models and Crew Decision Making

The importance of crew decision making to aviation safety has been well established through NTSB accident analyses: Crew judgment and decision making have been cited as causes or contributing factors in over half of all accidents in commercial air transport, general aviation, and military aviation. Yet the bulk of research on decision making has not proven helpful in improving the quality of decisions in the cockpit. One reason is that traditional analytic decision models are inappropriate to the dynamic complex nature of cockpit decision making and do not accurately describe what expert human decision makers do when they make decisions. A new model of dynamic naturalistic decision making is offered that may prove more useful for training or aiding cockpit decision making. Based on analyses of crew performance in full-mission simulation and National Transportation Safety Board accident reports, features that define effective decision strategies in abnormal or emergency situations have been identified. These include accurate situation assessment (including time and risk assessment), appreciation of the complexity of the problem, sensitivity to constraints on the decision, timeliness of the response, and use of adequate information. More effective crews also manage their workload to provide themselves with time and resources to make good decisions. In brief, good decisions are appropriate to the demands of the situation and reflect the crew's metacognitive skill. Effective crew decision making and overall performance are mediated by crew communication. Communication contributes to performance because it assures that all crew members have essential information, but it also regulates and coordinates crew actions and is the medium of collective thinking in response to a problem. This presentation will examine the relation between communication that serves to build performance. Implications of these findings for crew training will be discussed.

Orasanu, Judith↗

NASA NTRS1994

Perceptual Optimization of DCT Color Quantization Matrices

Many image compression schemes employ a block Discrete Cosine Transform (DCT) and uniform quantization. Acceptable rate/distortion performance depends upon proper design of the quantization matrix. In previous work, we showed how to use a model of the visibility of DCT basis functions to design quantization matrices for arbitrary display resolutions and color spaces. Subsequently, we showed how to optimize greyscale quantization matrices for individual images, for optimal rate/perceptual distortion performance. Here we describe extensions of this optimization algorithm to color images.

Watson, Andrew B.↗

NASA NTRS1994

The Barberplaid Illusion

Mulligan showed that the perceived direction of a moving grating can be biased by the shape of the Gaussian window in which it is viewed. We sought to determine if a 2-D pattern with an unambiguous velocity would also show such biases. Observers viewed a drifting plaid (sum of two orthogonal 2.5 c/d sinusoidal gratings of 12% contrast, each with a TF of 4 Hz.) whose contrast was modulated spatially by a stationary, asymmetric 2-D Gaussian window (i.e. unequal standard deviations in the principal directions). The direction of plaid motion with respect to the orientation of the window's major axis (Delta Theta) was varied while all other motion parameters were held fixed. Observers reported the perceived plaid direction of motion by adjusting the orientation of a pointer. All five observers showed systematic biases in perceived plaid direction that depended on Delta Theta and the aspect ratio of the Gaussian window (lambda). For circular Gaussian windows Lambda = 1), plaid direction was veridically perceived. However, biases of up to 10 deg. were found for lambda = 2 and Delta Theta = 30 deg. These data present a challenge to models of motion perception which do not explicitly consider the integration of information across the visual field.

Beutter, B. R.↗

NASA NTRS1994

Enhancing Displays by Blurring

Some Enhanced Vision cockpit displays consist of synthetic imagery superimposed on a real image. The high spatial frequency components of the synthetic imagery can mislead an operator by masking features of the real image. We demonstrate that blurring the synthetic image prior to superposition reduces its masking effect in high- contrast regions of the real image, while maintaining its enhancing properties in regions of the real image where visibility is low.

Tiana, C.↗

NASA NTRS1994

Color Breakup In Sequentially-Scanned LC Displays

In sequentially-scanned liquid-crystal displays the chromatic components of color pixels are distributed in time. For such displays eye, head, display, and image-object movements can cause the individual color elements to be visible. We analyze conditions (scan designs, types of eye movement) likely to produce color breakup.

Arend, L.↗

NASA NTRS1994

Decision Making in Action: Applying Research to Practice

The importance of decision-making to safety in complex, dynamic environments like mission control centers and offshore installations has been well established. NASA-ARC has a program of research dedicated to fostering safe and effective decision-making in the manned spaceflight environment. Because access to spaceflight is limited, environments with similar characteristics, including aviation and nuclear power plants, serve as analogs from which space-relevant data can be gathered and theories developed. Analyses of aviation accidents cite crew judgement and decision making as causes or contributing factors in over half of all accidents. A similar observation has been made in nuclear power plants. Yet laboratory research on decision making has not proven especially helpful in improving the quality of decisions in these kinds of environments. One reason is that the traditional, analytic decision models are inappropriate to multidimensional, high-risk environments, and do not accurately describe what expert human decision makers do when they make decisions that have consequences. A new model of dynamic, naturalistic decision making is offered that may prove useful for improving decision making in complex, isolated, confined and high-risk environments. Based on analyses of crew performance in full-mission simulators and accident reports, features that define effective decision strategies in abnormal or emergency situations have been identified. These include accurate situation assessment (including time and risk assessment), appreciation of the complexity of the problem, sensitivity to constraints on the decision, timeliness of the response, and use of adequate information. More effective crews also manage their workload to provide themselves with time and resources to make good decisions. In brief, good decisions are appropriate to the demands of the situation. Effective crew decision making and overall performance are mediated by crew communication. Communication contributes to performance because it assures that all crew members have essential information, but it also regulates and coordinates crew actions and is the medium of collective thinking in response to a problem. This presentation will examine the relations between leadership, communication, decision making and overall crew performance. Implications of these findings for spaceflight and training for offshore installations will be discussed.

Orasanu, Judith↗

NASA NTRS1994

Decision Making in Action

The importance of decision-making to safety in complex, dynamic environments like mission control centers and offshore installations has been well established. NASA-ARC has a program of research dedicated to fostering safe and effective decision-making in the manned spaceflight environment. Because access to spaceflight is limited, environments with similar characteristics, including aviation and nuclear power plants, serve as analogs from which space-relevant data can be gathered and theories developed. Analyses of aviation accidents cite crew judgement and decision making as causes or contributing factors in over half of all accidents. A similar observation has been made in nuclear power plants. Yet laboratory research on decision making has not proven especially helpful in improving the quality of decisions in these kinds of environments. One reason is that the traditional, analytic decision models are inappropriate to multidimensional, high-risk environments, and do not accurately describe what expert human decision makers do when they make decisions that have consequences. A new model of dynamic, naturalistic decision making is offered that may prove useful for improving decision making in complex, isolated, confined and high-risk environments. Based on analyses of crew performance in full-mission simulators and accident reports, features that define effective decision strategies in abnormal or emergency situations have been identified. These include accurate situation assessment (including time and risk assessment), appreciation of the complexity of the problem, sensitivity to constraints on the decision, timeliness of the response, and use of adequate information. More effective crews also manage their workload to provide themselves with time and resources to make good decisions. In brief, good decisions are appropriate to the demands of the situation. Effective crew decision making and overall performance are mediated by crew communication. Communication contributes to performance because it assures that all crew members have essential information, but it also regulates and coordinates crew actions and is the medium of collective thinking in response to a problem. This presentation will examine the relations between leadership, communication, decision making and overall crew performance. Implications of these findings for spaceflight and training for offshore installations will be discussed.

Orasanu, Judith↗

NASA NTRS1994

Enhanced/Synthetic Vision Systems for Advanced Flight Decks

One of the most challenging arenas for enhanced and synthetic vision systems is the flight deck. Here, pilots must perform active and supervisory control behaviors based on imagery generated in real time or transduced from imaging sensors. Although enhanced and synthetic vision technologies have been used in military vehicles for more than two decades, they have only recently been considered for civilian transport aircraft. In this paper we discuss the human performance issues still to be resolved for these systems, and consider the special constraints that must be considered for their use in the transport domain.

Kaiser, Mary K.↗

NASA NTRS1994

The Visibility of DCT Quantization Noise: Spatial Frequency Summation

Computational models of the ability to detect image compression artifacts facilitate the optimization of compression parameters, such as the JPEG quantization matrix. For simplicity, some models assume that the visibility of artifacts containing different spatial frequency components is determined by the most visible component, that is, no summation over components. Using the type of noise generated by quantization in the Discrete Cosine Transform (DCT) domain, we find a degree of summation between that of probability summation and contrast energy summation.

Peterson, H. A.↗

NASA NTRS1994

Effects of Perceptual Augmentation Of Visual Displays: Dissociation of Performance and Situational Awareness

It is intuitive that good performance is associated with, if not caused by, good situational awareness. There are, however, some situations in which these two concepts diverge. There are some trivial examples that have been identified, such as auto-pilots. However, it is also possible that these concepts diverge in a much more subtle manner. This research is focused on investigating those more subtle situations. Specifically, this research addresses the effects of perceptual display enhancement based upon Ecological Task Analysis (ETA) on performance and situational awareness. A perceptually augmented display was designed based upon ETA. Globally, performance advantages were found for the group with the enhanced display. Further, the findings demonstrate a dissociation of sub-task performance and operators' knowledge of the system subtask. The mechanisms involved in this dissociation are related to the characteristics of the display augmentation that led to the increased performance. The level of processing, and presence of feedback seem to play an important mediating role. These findings have important implications for both designers and researchers.

Shively, R. Jay↗