Research on physical and physiological aspects of visual optics in space flight

Physical and physiological aspects of visual optics in space fligh

Visuo-vestibular interaction in the reconstruction of travelled trajectories

We recently published a study of the reconstruction of passively travelled trajectories from optic flow. Perception was prone to illusions in a number of conditions, and not always veridical in the others. Part of the illusionary reconstructed trajectories could be explained by assuming that subjects base their reconstruction on the ego-motion percept built during the stimulus' initial moments . In the current paper, we test this hypothesis using a novel paradigm: if the final reconstruction is governed by the initial percept, providing additional, extra-retinal information that modifies the initial percept should predictably alter the final reconstruction. The extra-retinal stimulus was tuned to supplement the information that was under-represented or ambiguous in the optic flow: the subjects were physically displaced or rotated at the onset of the visual stimulus. A highly asymmetric velocity profile (high acceleration, very low deceleration) was used. Subjects were required to guide an input device (in the form of a model vehicle; we measured position and orientation) along the perceived trajectory. We show for the first time that a vestibular stimulus of short duration can influence the perception of a much longer lasting visual stimulus. Perception of the ego-motion translation component in the visual stimulus was improved by a linear physical displacement: perception of the ego-motion rotation component by a physical rotation. This led to a more veridical reconstruction in some conditions, but to a less veridical reconstruction in other conditions

Augmented Visibility in Architectural Space: Influencing Movement Patterns

The rapid development of computing associated with our modern era has resulted in exciting and innovative incorporation of digital technology in architectural design. However, this presents challenges for established theories of spatial analysis, such as space syntax, developed by Hillier and Hanson. The research presented in this thesis identifies and addresses a lack of knowledge concerning the impact of digitally manipulating physical architectural environments by introducing perceived visual depth into them. The research contributes to the development of space syntax theory by showing that the introduction of perceived visual depth in architectural space impacts on people’s behaviour, and that space syntax theory needs to be adjusted to account for this phenomenon. The overarching hypothesis of the experiments detailed by the thesis was that ambient displays can be introduced into physical architectural settings to augment the perceived visual depth of a space by virtually linking and extending physical space towards another real or virtual space. This augments the topological and visual relations of a space which influences how people use and move within such settings. To investigate the hypothesis a series of experiments was designed and conducted. A pilot study showed that manipulating the perceived depth of a wall through digital projection had a significant effect on people’s use of the space. The first of the main experiments showed that the position of an ambient display, acting as a virtual window through the wall upon which it was placed, had the capacity to influence people’s behaviour in space. This was established by designing a T-shaped corridor which participants entered from the bottom and were therefore required to make a left or right-hand turn decision to access a target area beyond the corridor. Whilst the environment was held constant the display was placed in one of three conditions, central, left, or right. The analysis showed that people’s turn-based decisions were affected by the position of the display. The second experiment used the same architectural setting but held the position of the ambient display constant in the central position whilst altering what it displayed in three conditions. The display either acted as a realistic virtual window, showing what would be seen if the display was a real window or it skewed the perspective of the image by manipulating the vanishing point towards the left or right. The turn-based decisions of participants entering the corridor were recorded and the results showed that they were significantly influenced by the manipulation. The experimental data showed that digital displays can act as virtual windows which alter spatial relations in a simple architectural space. This knowledge, combined with an awareness that current methods of spatial analysis cannot account for the impact of introducing digital depth into architectural space, show that theories must be adapted to ensure their ability to model behaviour in hybrid architectural environments which incorporate digital technology

Aerospace medicine and biology. A continuing bibliography with indexes, supplement 224

This bibliography lists 127 reports, articles, and other documents introduced into the NASA scientific and technical information system in September 1981

Influence of Auditory Cues on the visually-induced Self-Motion Illusion (Circular Vection) in Virtual Reality

This study investigated whether the visually induced selfmotion illusion (“circular vection”) can be enhanced by adding a matching auditory cue (the sound of a fountain that is also visible in the visual stimulus). Twenty observers viewed rotating photorealistic pictures of a market place projected onto a curved projection screen (FOV: 54°x45°). Three conditions were randomized in a repeated measures within-subject design: No sound, mono sound, and spatialized sound using a generic head-related transfer function (HRTF). Adding mono sound increased convincingness ratings marginally, but did not affect any of the other measures of vection or presence. Spatializing the fountain sound, however, improved vection (convincingness and vection buildup time) and presence ratings significantly. Note that facilitation was found even though the visual stimulus was of high quality and realism, and known to be a powerful vection-inducing stimulus. Thus, HRTF-based auralization using headphones can be employed to improve visual VR simulations both in terms of self-motion perception and overall presence

Functional requirements for the man-vehicle systems research facility

The NASA Ames Research Center proposed a man-vehicle systems research facility to support flight simulation studies which are needed for identifying and correcting the sources of human error associated with current and future air carrier operations. The organization of research facility is reviewed and functional requirements and related priorities for the facility are recommended based on a review of potentially critical operational scenarios. Requirements are included for the experimenter's simulation control and data acquisition functions, as well as for the visual field, motion, sound, computation, crew station, and intercommunications subsystems. The related issues of functional fidelity and level of simulation are addressed, and specific criteria for quantitative assessment of various aspects of fidelity are offered. Recommendations for facility integration, checkout, and staffing are included

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 125

This special bibliography lists 323 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1974

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 182, July 1978

This bibliography lists 165 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1978

Aniseikonia tests: The role of viewing mode, response bias, and size-color illusions.

PURPOSE To identify the factors responsible for the poor validity of the most common aniseikonia tests, which involve size comparisons of red-green stimuli presented haploscopically. METHODS Aniseikonia was induced by afocal size lenses placed before one eye. Observers compared the sizes of semicircles presented haploscopically via color filters. The main factor under study was viewing mode (free viewing versus short presentations under central fixation). To eliminate response bias, a three-response format allowed observers to respond if the left, the right, or neither semicircle appeared larger than the other. To control decisional (criterion) bias, measurements were taken with the lens-magnified stimulus placed on the left and on the right. To control for size-color illusions, measurements were made with color filters in both arrangements before the eyes and under binocular vision (without color filters). RESULTS Free viewing resulted in a systematic underestimation of lens-induced aniseikonia that was absent with short presentations. Significant size-color illusions and decisional biases were found that would be mistaken for aniseikonia unless appropriate action is taken. CONCLUSIONS To improve their validity, aniseikonia tests should use short presentations and include control conditions to prevent contamination from decisional/response biases. If anaglyphs are used, presence of size-color illusions must be checked for. TRANSLATIONAL RELEVANCE We identified optimal conditions for administration of aniseikonia tests and appropriate action for differential diagnosis of aniseikonia in the presence of response biases or size-color illusions. Our study has clinical implications for aniseikonia management