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Visual flow scene effects on the somatogravic illusion in non-pilots
Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
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2008 (English)In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, Vol. 79, no 9, 860-866 p.Article in journal (Refereed) Published
Abstract [en]

Introduction: The somatogravic illusion (SGI) is easily broken when the pilot looks out the aircraft window during daylight flight, but it has proven difficult to break or even reduce the SGI in non-pilots in simulators using synthetic visual scenes. Could visual-flow scenes that accommodate compensatory head movement reduce the SGI in naive subjects? Methods: We investigated the effects of visual cues on the SGI induced by a human centrifuge. The subject was equipped with a head-tracked, head-mounted display (HMD) and was seated in a fixed gondola facing the center of rotation. The angular velocity of the centrifuge increased from near zero until a 0.57-G centripetal acceleration was attained, resulting in a tilt of the gravitoinertial force vector, corresponding to a pitch-up of 30 degrees. The subject indicated perceived horizontal continuously by means of a manual adjustable-plate system. We performed two experiments with within-subjects designs. In Experiment 1, the subjects (N = 13) viewed a darkened TIMID and a presentation of simple visual flow beneath a horizon. In Experiment 2, the subjects (N = 12) viewed a darkened HMD, a scene including symbology superimposed on simple visual flow and horizon, and this scene without visual flow (static). Results: In Experiment 1, visual flow reduced the SGI from 12.4 +/- 1.4 degrees (mean +/- SE) to 8.7 +/- 1.5 degrees. In Experiment 2, the SGI was smaller in the visual flow condition (9.3 +/- 1.8 degrees) than with the static scene (13.3 +/- 1.7 degrees) and without HMD presentation (14.5 +/- 2.3 degrees), respectively. Conclusion: It is possible to reduce the SGI in non-pilots by means of a synthetic horizon and simple visual flow conveyed by a head-tracked HMD. This may reflect the power of a more intuitive display for reducing the SGI.

Place, publisher, year, edition, pages
2008. Vol. 79, no 9, 860-866 p.
Keyword [en]
spatial disorientation, spatial orientation, optic flow, HMD, flight-displays
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-109071DOI: 10.3357/ASEM.2264.2008ISI: 000258952200004OAI: oai:DiVA.org:uu-109071DiVA: diva2:248790
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2009-10-09Bibliographically approved
In thesis
1. Visual Flow Display for Pilot Spatial Orientation
Open this publication in new window or tab >>Visual Flow Display for Pilot Spatial Orientation
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Pilot spatial disorientation (SD) is a significant cause of incidents and fatal accidents in aviation. The pilot is susceptible to SD especially in low visibility when the visual system is deprived of information from outside the cockpit. This thesis presents the notion of visual flow displays as enhancement of symbology on flight displays primarily in low visibility for improved support of the pilot’s spatial orientation (SO) and control actions.

In Studies I and II, synthetic visual flow of forward ego-motion was presented on displays and postural responses were used as measures of display effectiveness in determining SO. The visual flow significantly affected SO, and although the increased stimulation of the visual periphery from a width of 45° to about 105° increased the effects there was no further effect at a width of about 150° (Studies I and II). Studies I and II also showed that omitting 20°- or 30°-wide central fields of view from the visual flow either reduced or not reduced the effects. Further, although inconclusive, Study II may indicate that horizon symbology in central visual field may enhance the effects of peripheral visual flow. The appropriate integration of peripheral visual flow with the head-up display symbology of the Gripen aircraft was presented.

Acceleration in a human centrifuge was used in Study III to investigate the effects of synthetic visual flow on the primarily vestibular-dependent somatogravic illusion of pitch-up. Two experiments revealed a reduced illusion with the visual flow. The results of Experiment 2 showed the visual flow scene not only reduced the illusion compared with a darkness condition but also compared with the visual scene without visual flow. Thus, similar to the main findings of Studies I and II, synthetic visual flow can significantly affect SO and supports the visually dependent SO system in an essential manner.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 110 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Social Sciences, ISSN 1652-9030 ; 53
Optic flow, visual flow, peripheral vision, spatial orientation, spatial disorientation, postural control, somatogravic illusion, human centrifuge, flight displays, head-up display, head-mounted display
National Category
Research subject
urn:nbn:se:uu:diva-111273 (URN)978-91-554-7684-7 (ISBN)
Public defence
2010-01-29, Sal IV, Universitetshuset, Uppsala, 13:00 (English)
Available from: 2010-01-08 Created: 2009-12-08 Last updated: 2010-01-08Bibliographically approved

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