Perception of Upright and vertical and investigation of self-orientation under differing Gravity States created by a Centrifuge - Trial DRKS00029681

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Summary

Amendment dated 13.10.2016: Under normal terrestrial conditions, people are always aware of their orientation in space. space at all times. The decision where "up" is happens as if by itself. The same applies to the perception "vertical" and "horizontal". But on closer examination of the perception one recognizes a very complex process. The perception of "above, vertical and horizontal" is influenced by a multitude of different stimuli, z. e.g. the kind of representation (visual stimuli), the orientation of a body in space (idiotropic stimuli), and gravity, which confirms to everyone under normal conditions where "up" and "down" is and thus what is to be evaluated as "vertical" and "horizontal." Usually these sensory stimuli are in agreement with each other, but in unusual environments, such as underwater or in outer space, these sensory stimuli may conflict or individual stimuli may be absent altogether. When these sensory impressions become ambiguous, they can deceive the perceiver and lead to a false perception of body orientation. The person then no longer knows for sure where up is and what is "vertical," which can result in fatal errors. Reports of accidents while diving and in space are full of examples where divers and pilots have lost orientation, resulting in sometimes fatal accidents have occurred. There are also other applications in the field of aviation research, particularly in perception from "above" during complex flight maneuvers such as high speed turns and the like. In addition, there are persons whose ability to use gravity as a source of information for perception is already limited/unreliable even under normal terrestrial conditions, as is more often the case with old or disabled people. occurs. Following an investigation of perception from "above" in the context of the PUG study, additional investigations will now be conducted to determine how people determine the orientation of objects in space without the availability of visual features. In this context, the rotation of a centrifuge provides a unique opportunity to systematically manipulate the direction of the gravitational vector (as the sum of natural gravity plus centripetal acceleration¸ total gravito-inertial acceleration (GIA)), i.e., without co-activation of semicircular canals. It will now be investigated to what extent subjects make decisions about the orientation of objects during centrifugation based during centrifugation solely on the basis of otolithic features without support from other (e.g., visual) features. It is hypothesized that the perceived orientation during centrifugation by a seated subject will be does not result directly from the vector sum of natural gravity and centripetal acceleration. Rather, it is hypothesized that perceived orientation varies as a function of the present level of radial acceleration as well as inclination features provided by the visually perceived environment. . Our hypothesis is that visual orientation features significantly influence the perceived orientation of objects. This influence is particularly effective when the visual features match the orientation of the subject of the previous produced radial acceleration. This behavior is based on the tendency of the orientation system to "orient" to previous best estimates and to derive further estimates based on previous ones. The precise quantification of the threshold above which a perceptible contribution of gravity to the determination of PU can be detected provides important additional information here.

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