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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Experimental study of visual accommodation

A summary report of a research effort related to the human visual accommodation system is presented. A theoretical study of the accommodation system was made. Subsequent effort was aimed at the development of specialized instrumentation for experiments designed to lead to understanding the nature of the control system in human accommodation. The necessary instrumentation consisted primarily of: (1) an automatic optometer to measure the state of eye focus, (2) a focus stimulator device to control the apparent optical distance to any target, and (3) a two-dimensional eye tracker. The concepts and designs of the first two instruments have been published in the open literature, but this report contains the first detailed treatment of the Purkinje eye tracker developed under this program. The report also discusses an accommodation lag model to explain the ability of the eye to apparently know the polarity of focus error even though the blur on the retina is to a first-approximation an even function. The interaction of the accommodation and eye movement systems is also discussed, as is the ability to train the visual accommodation system to a surprisingly responsive condition in only a few hours of training.

Cornsweet, T. N.↗
NASA NTRS1972

The visual standards for the selection and retention of astronauts, part 2

In preparation for the various studies planned for assessing visual capabilities and tasks in order to set vision standards for astronauts, the following pieces of equipment have been assembled and tested: a spectacle obstruction measuring device, a biometric glare susceptibility tester, a variable vergence amplitude testing device, an eye movement recorder, a lunar illumination simulation chamber, a night myopia testing apparatus, and retinal adaption measuring devices.

Allen, M. J.↗
NASA NTRS1972

Electrophysiological studies of the nervous system

The electrophysiology of the nervous system is studied using cats and human subjects. Data cover effects of chlorolose on evoked potential, the evoked resistance shift that accompanies evoked potentials, and the relationship of eye movements to potentials aroused by visual stimulation.

Galambos, R.↗
NASA NTRS1971

Chimpanzee sleep stages.

The electroencephalogram and electro-oculogram of two unrestrained juvenile chimpanzees was monitored for 7 consecutive nights using telemetry methods. Of the sleeping time, 23% was spent in the rapid eye movement of REM type of sleep, whereas 8, 4, 15, and 10% were spent in non-REM stages 1 through 4, respectively. Seven to nine periods of REM sleep occurred per night. The average time from the beginning of one REM period to the beginning of the next was approximately 85 min.

Freemon, F. R.↗
NASA NTRS1971

A model describing vestibular detection of body sway motion.

An experimental technique was developed which facilitated the formulation of a quantitative model describing vestibular detection of body sway motion in a postural response mode. All cues, except vestibular ones, which gave a subject an indication that he was beginning to sway, were eliminated using a specially designed two-degree-of-freedom platform; body sway was then induced and resulting compensatory responses at the ankle joints measured. Hybrid simulation compared the experimental results with models of the semicircular canals and utricular otolith receptors. Dynamic characteristics of the resulting canal model compared closely with characteristics of models which describe eye movement and subjective responses to body rotational motions. The average threshold level, in the postural response mode, however, was considerably lower. Analysis indicated that the otoliths probably play no role in the initial detection of body sway motion.

Nashner, L. M.↗
NASA NTRS1972

Sleep deprivation and the organization of the behavioral states.

Questions concerning the significance of sleep in the developing organism are investigated, together with the mechanisms that underlie the unique distribution of behavioral states at any particular age and during any particular experimental manipulation. It is attempted to define the states of sleep and wakefulness in terms of a temporal confluence of a number of more or less independent processes, taking also into account the functional consequences of these attributes. The results of a selective deprivation of rapid eye movement sleep are explored, giving attention to effects on sleep, behavioral changes, brain excitability, pharmacological changes, and biochemical changes.

Dement, W. C.↗
NASA NTRS1973

Responses to rotating linear acceleration vectors considered in relation to a model of the otolith organs

Human subjects were exposed to a linear acceleration vector that rotated in the transverse plane of the skull without angular counterrotation. Lateral eye movements showed a sinusoidal change in slow phase velocity and an asymmetry or bias in the same direction as vector rotation. A model is developed that attributes the oculomotor response to otolithic mechanisms. It is suggested that the bias component is the manifestation of torsion of the statoconial plaque relative to the base of the utricular macula and that the sinusoidal component represents the translational oscillation of the statoconia. The model subsumes a hypothetical neural mechanism which allows x- and y-axis accelerations to be resolved. Derivation of equations of motion for the statoconial plaque in torsion and translation, which take into account forces acting in shear and normal to the macula, yield estimates of bias and sinusoidal components that are in qualitative agreement with the diverse experimental findings.

Benson, A. J.↗
NASA NTRS1973

Systems analysis of the vestibulo-ocular system

The vestibulo-ocular system is examined from the standpoint of system theory. The evolution of a mathematical model of the vestibulo-ocular system in an attempt to match more and more experimental data is followed step by step. The final model explains many characteristics of the eye movement in vestibularly induced nystagmus. The analysis of the dynamic behavior of the model at the different stages of its development is illustrated in time domain, mainly in a qualitative way.

Schmid, R. M.↗
NASA NTRS1975

Integration of visual and motion cues for simulator requirements and ride quality investigation

Preliminary tests and evaluation are presented of pilot performance during landing (flight paths) using computer generated images (video tapes). Psychophysiological factors affecting pilot visual perception were measured. A turning flight maneuver (pitch and roll) was specifically studied using a training device, and the scaling laws involved were determined. Also presented are medical studies (abstracts) on human response to gravity variations without visual cues, acceleration stimuli effects on the semicircular canals, and neurons affecting eye movements, and vestibular tests.

Young, L. R.↗
NASA NTRS1975

Biocybernetic factors in human perception and memory

The objective of this research is to develop biocybernetic techniques for use in the analysis and development of skills required for the enhancement of concrete images of the 'eidetic' type. The scan patterns of the eye during inspection of scenes are treated as indicators of the brain's strategy for the intake of visual information. The authors determine the features that differentiate visual scan patterns associated with superior imagery from scan patterns associated with inferior imagery, and simultaneously differentiate the EEG features correlated with superior imagery from those correlated with inferior imagery. A closely-coupled man-machine system has been designed to generate image enhancement and to train the individual to exert greater voluntary control over his own imagery. The models for EEG signals and saccadic eye movement in the man-machine system have been completed. The report describes the details of these models and discusses their usefulness.

Lai, D. C.↗
NASA NTRS1979

Eye-controlled switch

Eye motion sensor clipped to standard eyeglass frame and circuit allows electric wheel chair to be controlled by eye movements alone.

Walker, G. L.↗
NASA NTRS1980

Physiological response to hyper- and hypogravity during rollercoaster flight

Twenty-six healthy male subjects were flown in a Lear jet aircraft through rollercoaster and parabolic weightlessness flight. Eye movements, respiration, and blood volume pulse were recorded on magnetic tape. The same subjects underwent a battery of five vestibular tests in the laboratory on the ground. One subject in each flight was flown in an upright position, the other in a 90 deg forward tilted head position. The forward tilted subjects always reported motion sickness earlier and after fewer rollercoaster maneuvers than the upright-sitting subjects. It is concluded that the susceptibility to changes of X-axis acceleration is higher than to changes of Z-axis acceleration. Correlation was found between the ability to estimate the subjective vertical (modified Mueller-Aubert-test), optokinetic nystagmus asymmetries, and susceptibility to rollercoaster flight sickness.

Von Baumgarten, R. J.↗
NASA NTRS1980

Optimal control model predictions of system performance and attention allocation and their experimental validation in a display design study

The influence of different types of predictor displays in a longitudinal vertical takeoff and landing (VTOL) hover task is analyzed in a theoretical study. Several cases with differing amounts of predictive and rate information are compared. The optimal control model of the human operator is used to estimate human and system performance in terms of root-mean-square (rms) values and to compute optimized attention allocation. The only part of the model which is varied to predict these data is the observation matrix. Typical cases are selected for a subsequent experimental validation. The rms values as well as eye-movement data are recorded. The results agree favorably with those of the theoretical study in terms of relative differences. Better matching is achieved by revised model input data.

Johannsen, G.↗
NASA NTRS1979

Monitoring and decision making by people in man machine systems

The analysis of human monitoring and decision making behavior as well as its modeling are described. Classic and optimal control theoretical, monitoring models are surveyed. The relationship between attention allocation and eye movements is discussed. As an example of applications, the evaluation of predictor displays by means of the optimal control model is explained. Fault detection involving continuous signals and decision making behavior of a human operator engaged in fault diagnosis during different operation and maintenance situations are illustrated. Computer aided decision making is considered as a queueing problem. It is shown to what extent computer aids can be based on the state of human activity as measured by psychophysiological quantities. Finally, management information systems for different application areas are mentioned. The possibilities of mathematical modeling of human behavior in complex man machine systems are also critically assessed.

Johannsen, G.↗
NASA NTRS1981

A binocular contribution to the production of optokinetic nystagmus in normal and stereoblind subjects

Viewing a large patterned field moving in one direction produces a regular pattern of eye movements known as optokinetic nystagmus (OKN). Fox et al. (1978) showed that the mechanism producing OKN can utilize purely binocular or 'cyclopean' input. Experiments reported confirm that finding and extend it to demonstrate that the binocularity of this mechanism is not disrupted in subjects who lack stereopsis. This result indicates that there exists more than one binocular process in the visual system.

Wolfe, J. M.↗
NASA NTRS1981

Visual fatigue - The need for an integrated model

Two experiments were conducted to examine possible decrements in performance over time on two visual tracking tasks. In Experiment 1, six subjects tracked a horizontal, sinusoidally moving target in the picture plane for 6.5 min. In Experiment 2, six subjects tracked a target sinusoidally changing focus in the depth plane between 0 and 4 D over 6.5 min. Results indicated a linearly decreasing amplitude of both pursuit eye movements (.29 deg of visual angle per minute) and accommodation (.11 D/min). These visual fatigue effects are discussed in the context of several competing explanations.

Malmstrom, F. V.↗
NASA NTRS1981

Pilot scanning patterns while viewing cockpit displays of traffic information

Scanning eye movements of airline pilots were recorded while they judged air traffic situations displayed on cockpit displays of traffic information (CDTI). The observed 1st order transition patterns between points of interest on the display showed reliable deviation from those patterns predicted by the assumption of statistical independence. However, both patterns of transitions correlated quite well with each other. Accordingly, the assumption of independence provided a surprisingly good model of the results. Nevertheless, the deviation between the observed patterns of transition and that based on the assumption of independence was for all subjects in the direction of increased determinism. Thus, the results provide objective evidence consistent with the existence of "scanpaths" in the data.

Ellis, S. R.↗
NASA NTRS1983

Simulation fidelity and numerosity effects in CDTI experimentation

Twenty pilot workload assessment techniques were compared using a simulated flying task in which three levels of psychomotor workload were imposed. The experiment was conducted in a three degree of freedom motion base simulator. Opinion measures, spare mental capacity measures, physiological measures, eye movement behavior and primary task performance measures were evaluated. The primary task was an instrument landing system (ILS) approach and landing. All measures were recorded between the outer and middle markers on the approach. Three levels of psychomotor load were obtained by the combined manipulation of wind gust disturbance level and simulated aircraft pitch stability. Six instrument rated general aviation pilots participated in the experiment. Cooper-Harper ratings, WCI/TE ratings, time estimation standard deviation, pulse rate mean, and control movements per unit time demonstrated sensitivity to psychomotor load. No intrusion into primary task performance was found that the sensitivities of workload estimation techniques vary widely, and that only a few techniques appear to be sensitive to psychomotor load.

Kreifeldt, J. G.↗