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Physical characteristics of human responses to weightlessness simulation during parabolic flights establish body immobilization and visual illusions as the most manifest causes of sensory distrubances. Repeated brief weightlessness exposures gradually decreased expressions of static-kinetic disorders.
The performance quality of movements away and approaches to an airlock by astronauts was tested during parabolic flights for weightlessness simulation. Coordination of movement, orientation and performance capacity of the astronauts were not singificantly disrupted. Observed physiological shifts are characterized by an increase in pulse and respiration rate and an increase in arterial pressure under g-forces, a gradual decrease in these indices during repeated stays in weightlessness or during the prolonged effect of it, by a reduction of the length of postrotational nystagmus and counterrotation illusions under weightless conditions.
An educational toy useful in demonstrating fundamental concepts regarding the laws of gravity is described. The device comprises a sphere 10 of radius r resting on top of sphere 12 of radius R. The center of gravity of sphere 10 is displaced from its geometrical center by distance D. The dimensions are so related that D((R+r)/r) is greater than r. With the center of gravity of sphere 10 lying on a vertical line, the device is in equilibrium. When sphere 10 is rolled on the surface of sphere 12 it will return to its equilibrium position upon release. This creates an illusion that sphere 10 is defying the laws of gravity. In reality, due to the above noted relationship of D, R, and r, the center of gravity of sphere 10 rises from its equilibrium position as it rolls a short distance up or down the surface of sphere 12.
Dc command voltages from analog computer can be displayed as four dots and two crosshairs configured to provide illusion of depth via planar or stereo presentations in monochrome or color and if stereo, using dual monitors, single monitor with split screen, or single monitor with color separation.
An experiment was conducted in order to determine the relative effectiveness of several hypothetical jet engine noise treatments and to test hypothesis that speech interference, at least in part, mediates annoyance in a TV-viewing situation. Twenty-four subjects watched television in a simulated living room. Recorded jet flyover noises were presented in such a way as to create the illusion that aircraft were actually flying overhead. There were 27 stimuli (nine spectra at three overall levels) presented at an average rate of approximately one flight every 2 minutes. Subjects judged the annoyance value of individual stimuli using either a category rating method or magnitude estimation method in each of two 1-hour sessions. The spectral treatments most effective in reducing annoyance were at 1.6 Khz and 800 Hz, in that order. The degree of annoyance reduction resulting from all treatments was affected by the overall sound level of the stimuli, with the greatest reduction at the intermediate overall sound level, about 88 to 89 db(A), peak value. The results are interpreted as supporting the hypothesis that speech interference, at least in part, mediates annoyance with aircraft noise in a TV-viewing situation.
Information regarding the influence on sensory perception of certain space flight factors, including weightlessness, acceleration, and vibration, is presented. Several illusions which occur under these conditions are described. The results of ground based experiments are also discussed.
Approach lighting system employing combinations of red and blue lights reduces problem of color-based optical illusions. System exploits inherent chromatic aberration of eye to create three-dimensional effect, giving pilot visual clues of position.
The lower susceptibility to vestibular stimulation aloft, compared with that on ground under experimental conditions, is attributed to a precondition, namely, either there is no need to adapt, or, as exemplified by the Skylab 3 pilot, adaptation to weightlessness is achieved. Findings in some of the astronauts emphasize the distinction between two categories of vestibular side effects: immediate reflex phenomena (illusions, sensations of turning, etc.), and delayed epiphenomena that include the constellation of symptoms and syndromes comprising motion sickness. The drug combinations 1-scopolamine and d-amphetamine and promethazine hydrochloride and ephedrine sulfate are effective in prevention and treatment of motion sickness. It is concluded that prevention of motion sickness in any stressful motion environment involves selection, adaptation, and the use of drugs.
Subjects seated in darkness often experience illusory self-rotation when exposed to a rotating sound field. Compelling illusions of a self-rotation are generally accompanied by nystagmoid movements of the eyes with the slow phase in the direction opposite that of the experienced self-rotation. These phenomena are related to the functioning of a spatial constancy mechanism by which a stable distinction is normally maintained between movements of self and movements of the environment. The appearance of nystagmus during illusory self-rotating indicates that apparent body orientation can influence oculomotor control.
This paper presents a model for the perception of dynamic orientation resulting from stimuli which involve both the otoliths and the semicircular canals. The model was applied to several multisensory stimuli and its predictions evaluated. In all cases, the model predictions were in substantial agreement with the known illusions or with the relevant experimental data.
Nine college age males, all prone to motion sickness, were subjects in an experiment designed to test adaptation to motion. Subjects were placed in a slow rotation room (SRR) for varying intervals and asked to perform headward movements. Degree of adaptation to the SRR was measured in the framework of 3 categories: reduction of ataxia, reduction of oculogyral illusion, and reduction of epiphenomena, which includes symptoms of motion sickness. 'Satisfactory' adaptation was acquired and retained in 7 of the 9 subjects. Tables are presented summarizing the results.
On the earth, or in level flight, a blindfolded subject being rotated at constant velocity about his recumbent long body axis experiences illusory orbital motion of his body in the opposite direction. By contrast, during comparable rotation in the free-fall phase of parabolic flight, no body motion is perceived and all sense of external orientation may be lost; when touch and pressure stimulation is applied to the body surface, a sense of orientation is reestablished immediately. The increased gravitoinertial force period of a parabola produces an exaggeration of the orbital motion experienced in level flight. These observations reveal an important influence of touch, pressure, and kinesthetic information on spatial orientation and provide a basis for understanding many of the postural illusions reported by astronauts in space flight.
Both the effectiveness of pilot training and the safety of flight can be influenced by the distribution of texture in the visual scene, the distance to which the eyes accommodate, and the associated shifts in the apparent size and distance of objects in central and peripheral vision. Studies reviewed and original results presented indicate that these factors are involved in various misjudgments and illusions experienced by pilots: (1) when searching for other airborne traffic or targets, (2) when making approaches to airports over water at night, (3) when breaking out of low clouds on a final approach to a landing by reference to head-up or head-down displays, and (4) when practicing simulated approaches and landings or air-to-surface weapon deliveries by reference to synthetically generated visual systems.
The experimental demonstration of a reversal of the circularvection (CV) phenomenon is reported. After one to three hours of active movement while wearing vision-reversing goggles, 9 of 12 stationary human subjects viewing a moving stripe display experienced a self-rotation illusion in the same direction as the seen stripe motion. In addition, the subjects showed a 17% reduction in vestibulo-ocular reflex slow phase gain over their brief exposure period. It is noted that whether a subject demonstrated reversed CV within the allowed exposure period appeared to be correlated with CV strength produced with a narrow field stimulus.
It was revealed that during the tests with continuous action of sign variable Coriolis acceleration the development of kinetosis was proportionate to the time of head inclinations in the range of 1 to 4 seconds while illusions of rocking in sagittal plane was more expressed in fast inclinations. The obtained data provided the evidence of sufficient dependence of vestibulovegetative and vestibulosensory reactions on the period of repetition of sign variable Coriolis acceleration.
Vestibulo-sensory reactions were studied in 135 workers who were in contact with nitroethers, by the method of an experimental caloric test. The response vestibulo-sensory reactions were recorded by means of an electroencephalograph. The changes in the sensory reaction depended on the duration of the workers' contact with toxic agents. A study of illusion reactions by the labyrinth calorization widens diagnostic possibilities in the examination of functional condition of the vestibular analyser considerably.
The influence of meprobamate on the vestibular illusion of counter-rotation, movement coordination and vertical writing was investigated by a double blind trial method and placebo. The results confirm the possibility of the meprobamate application for prophylaxis and correction of vestibular disturbances.
The set of experiments comprising the Spacelab 1ES201 package designed to investigate the human vestibular system and equilibratory function in weightlessness are described. The specific objectives of the experiments include: (1) the determination of the threshold of perception of linear oscillatory motion; (2) measurement of physiological and subjective responses to supra threshold, linear and angular motion stimuli; (3) study of the postural adjustments, eye movements, and illusions of attitude and motion evoked by optokinetic stimuli, (i.e., moving visual patterns) in order to assess visual/vestibular interactions; (4) examination of the effect of thermal stimulations of the vestibular apparatus to determine if the eye movements elicited by the 'caloric test' are used by a density gradient in the semicircular canal; and (5) investigation of the pathogenesis of space motion sickness by recording signs and symptoms during the course of vestibular stimulation and, specifically, when the test subject is exposed to sustained, linear oscillatory motion.