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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Distortion of Perceived Visual Space after Eccentric Gaze Holding

Previous studies have shown that rebound nystagmus can be a behavioral probe into the adaptive properties of the gaze-holding mechanism, showing that after prolonged eccentric gaze holding and upon return to central gaze the eye tends to drift towards the previously held position. It is not known whether perception of visual space is also affected by similar adaptation mechanisms. The current study seeks to elucidate if eccentric gaze holding changes the perception of space in a relative spatial judgment task. To measure their spatial bias, twelve subjects were asked to report which among two short vertical lines flashed to the left or to the right of the display was closer to a third central line. Perception was assessed after holding eccentric gaze at 40 degrees towards the left or right and compared with control trials without eccentric gaze holding. Subjects showed a significant difference in spatial bias between the leftward and rightward gaze holding conditions (p = 0.04), suggesting that the visual space changes differently with respect to the side where gaze was held. While we did not observe an overall bias (p = 0.327) under no gaze holding we did observe a significant correlation between handedness and spatial bias (r2 = 0.4, p = 0.04). We conclude that gaze holding temporarily distorts the perception of space in a mechanism that may be related to the adaptation of the gaze holding mechanism.

perception↗
NASA NTRS1987

How to reinforce perception of depth in single two-dimensional pictures

The physical conditions of the display of single 2-D pictures, which produce images realistically, were studied by using the characteristics of the intake of the information for visual depth perception. Depth sensitivity, which is defined as the ratio of viewing distance to depth discrimination threshold, was introduced in order to evaluate the availability of various cues for depth perception: binocular parallax, motion parallax, accommodation, convergence, size, texture, brightness, and air-perspective contrast. The effects of binocular parallax in different conditions, the depth sensitivity of which is greatest at a distance of up to about 10 m, were studied with the new versatile stereoscopic display. From these results, four conditions to reinforce the perception of depth in single pictures were proposed, and these conditions are met by the old viewing devices and the new high-definition and wide television displays.

S. Nagata↗
NASA NTRS2001

Imagining physically impossible self-rotations: geometry is more important than gravity

Previous studies found that it is easier for observers to spatially update displays during imagined self-rotation versus array rotation. The present study examined whether either the physics of gravity or the geometric relationship between the viewer and array guided this self-rotation advantage. Experiments 1-3 preserved a real or imagined orthogonal relationship between the viewer and the array, requiring a rotation in the observer's transverse plane. Despite imagined self-rotations that defied gravity, a viewer advantage remained. Without this orthogonal relationship (Experiment 4), the viewer advantage was lost. We suggest that efficient transformation of the egocentric reference frame relies on the representation of body-environment relations that allow rotation around the observer's principal axis. This efficiency persists across different and conflicting physical and imagined postures.

NASA Discipline Space Human Factors↗
NASA NTRS2003

Visual Cueing Effects Investigation for a Hovering Task

In simulators, as in actual aircraft, pilots conduct their missions according to perceived vehicle performance and spatial orientation from out-the-window (OTW) information. Ground-based flight simulations rely upon computer-generated OTW visual scenes. The realism and fidelity of a specific OTW simulation therefore has a significant impact on mission effectiveness. This study investigates effects of three visual parameters of the computer-generated image system (field-of-view, collimation, and resolution) on a disturbance-rejection hovering task. Pilots' performance and workload were studied under the following conditions: collimated optics vs. noncollimated optics, wide field-of-view (FOV) vs. narrow FOV, and higher resolution vs. lower resolution. Subjects were instructed to maintain a station-keeping position during disturbances while piloting an uncoupled four degrees-of-freedom (DOF) helicopter model, which had a satisfactory rate-command system in pitch and roll axes and ideal heading and altitude hold. Display collimation and FOV were found to have significant effects on pilots performance and subjective their subjective perception of visual cueing quality.

Chung, William W. Y.↗
NASA NTRS2003

The effects of study-task relevance on perceptual repetition priming

Repetition priming is easily elicited in many traditional paradigms, and the possibility that perceptual priming may be other than an automatic consequence of perception has received little consideration. This issue is explored in two experiments. In Experiment 1, participants named the target from a four-item category search study task more quickly than the nontarget study items at a later naming test. Experiment 2 extended this finding to conditions in which stimuli were individually presented at study. In three different study tasks, stimuli relevant to study-task completion elicited priming on a later test, but stimuli presented outside the context of a task did not. In both experiments, recognition was above chance for nonrelevant stimuli, suggesting that participants explicitly remembered stimuli that did not elicit priming. Results suggest that priming is sensitive to study-task demands and may reflect a more adaptive and flexible mechanism for modification of perceptual processing than previously appreciated.

Visual Perception↗