Perception and Awareness of Spatial Orientation Following Transitions in the Availability of Visual Information

Pilots of aircraft and spacecraft experience sudden changes in the availability of visual information during the manual control of aerospace vehicles. For example, visual perceptual cues are suddenly lost when a pilot flies into a cloud. Visual information from flight deck instrumentation is suddenly gained when a pilot&rsquo;s gaze saccades to the attitude indicator. These are just two scenarios describing sudden loss or gain of visual information, both are commonplace during flight. The presence of visual information impacts the accuracy of a pilot&rsquo;s perception of spatial orientation. Further, a pilot may perceive or feel one vehicle orientation, but have an understanding of another orientation based on instrument information which I term &rdquo;orientation awareness&rdquo;. Pilots must maintain accurate perception or orientation awareness to maintain control of a manually operated vehicle. Therefore, perceptual and orientation awareness dynamics must be well understood for the successful operation and design of crewed vehicles. A series of experiments were run to characterize the dynamics of orientation perception and orientation awareness following a sudden loss or gain of visual information. Angular velocity perception during earth vertical yaw motion was quantified following a sudden gain and sudden loss of naturalistic visual cues. Human subjects gradually integrated the sudden gain of visual cues over the course of approximately 10 seconds. Past visual cues continued to impact angular velocity perception up to 40 seconds following a sudden loss of naturalistic visual cues. Similarly, tilt perception was quantified following a sudden gain and sudden loss of naturalistic visual cues containing angular velocity and visual horizontality cues. Tilt perception was also quantified following the sudden gain and sudden loss of an attitude indicator (artificial horizon). Again, subjects gradually integrated the new naturalistic visual cue information over a course of approximately 3 seconds. However, human subjects far more slowly integrated the new visual information as presented via an attitude indicator. It took approximately 6 seconds (twice as long) for humans to integrate information from the attitude indicator into their perception of tilt. Past visual cues continued to influence tilt perception for up to 10 seconds following a sudden loss of visual information from both the naturalistic visual cues and attitude indicator. Tilt awareness and tilt perception were quantified following sudden gain and sudden loss of an attitude indicator. In contrast to perception, human subjects immediately integrated the new information from the attitude indicator into their orientation awareness following its sudden appearance. Similarly, past information from the attitude indicator influenced tilt awareness for up to 10 seconds beyond sudden loss of the visual information. A novel model of orientation perception that is consistent with the data collected in this thesis is presented. Previous models of orientation perception have not been robust to sudden gain or loss of naturalistic visual cues. The use of low pass filtering in the corresponding visual cue pathways (within the model) reconciles differences. In conclusion, this thesis presents empirical quantification of perception and understanding of orientation following sudden transitions in the availability of visual information in addition to a model of orientation perception that is consistent with the data.</p

Galvanic vestibular stimulation produces cross-modal improvements in visual thresholds

Background: Stochastic resonance (SR) refers to a faint signal being enhanced with the addition of white noise. Previous studies have found that vestibular perceptual thresholds are lowered with noisy galvanic vestibular stimulation (i.e., "in-channel" SR). Auditory white noise has been shown to improve tactile and visual thresholds, suggesting "cross-modal" SR. Objective: We aimed to study the cross-modal impact of noisy galvanic vestibular stimulation (nGVS) (n=9 subjects) on visual and auditory thresholds. Methods: We measured auditory and visual perceptual thresholds of human subjects across a swath of different nGVS levels in order to determine if a subject-specific best nGVS level elicited a reduction in thresholds as compared the no noise condition (sham). Results: We found an 18% improvement in visual thresholds (p = 0.026). Among the 7 of 9 subjects with reduced thresholds, the average improvement was 26%. Subjects with higher (worse) visual thresholds with no stimulation (sham) improved more than those with lower thresholds (p = 0.005). Auditory thresholds were unchanged by vestibular stimulation. Conclusions: These results are the first demonstration of cross-modal improvement with nGVS, indicating galvanic vestibular white noise can produce cross-modal improvements in some sensory channels, but not all.Comment: 15 pages, 7 figure

Innovation in emergency housing with a focus on Nepal

Thesis: S.B., Massachusetts Institute of Technology, Department of Architecture, 2016.Cataloged from PDF version of thesis.Includes bibliographical references (pages 71-72).Abstract Every year millions of people are displaced due to natural disasters and very primitive transitional shelters, or 't-shelters', exist to provide semi-permanent housing. Many t-shelter designs do not cater to all the needs of their inhabitants and are only functional in the short term, often leaving many people relying on t-shelters for housing in an unsafe and unsanitary environment. This thesis addresses the problem of people needing housing and of unsafe transitional housing by presenting a new design process and ultimately a t-shelter design specifically for the victims of the 2015 earthquakes in Nepal in the Kathmandu area. The process involves three key elements; identifying the specific needs of the displaced people, analyzing what materials and labor are available and ensuring that the shelter will be used as intended and therefore remain safe. The resulting shelter design harnesses the structural strength of the geodesic dome, the simplicity of reciprocal joinery and strong yet lightweight nature of bamboo. The effectiveness of the proposed new design process is demonstrated through checking the resulting shelter design meeting measurable outcomes like cost, structural integrity and skill level required to construct.by Jamie L. Voros.S.B