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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Mitigation Of Motion Sickness Symptoms In 360 Degree Indirect Vision Systems

Quinn, Stephanie 01 January 2013 (has links)
The present research attempted to use display design as a means to mitigate the occurrence and severity of symptoms of motion sickness and increase performance due to reduced “general effects” in an uncoupled motion environment. Specifically, several visual display manipulations of a 360° indirect vision system were implemented during a target detection task while participants were concurrently immersed in a motion simulator that mimicked off-road terrain which was completely separate from the target detection route. Results of a multiple regression analysis determined that the Dual Banners display incorporating an artificial horizon (i.e., AH Dual Banners) and perceived attentional control significantly contributed to the outcome of total severity of motion sickness, as measured by the Simulator Sickness Questionnaire (SSQ). Altogether, 33.6% (adjusted) of the variability in Total Severity was predicted by the variables used in the model. Objective measures were assessed prior to, during and after uncoupled motion. These tests involved performance while immersed in the environment (i.e., target detection and situation awareness), as well as postural stability and cognitive and visual assessment tests (i.e., Grammatical Reasoning and Manikin) both before and after immersion. Response time to Grammatical Reasoning actually decreased after uncoupled motion. However, this was the only significant difference of all the performance measures. Assessment of subjective workload (as measured by NASA-TLX) determined that participants in Dual Banners display conditions had a significantly lower level of perceived physical demand than those with Completely Separated display designs. Further, perceived iv temporal demand was lower for participants exposed to conditions incorporating an artificial horizon. Subjective sickness (SSQ Total Severity, Nausea, Oculomotor and Disorientation) was evaluated using non-parametric tests and confirmed that the AH Dual Banners display had significantly lower Total Severity scores than the Completely Separated display with no artificial horizon (i.e., NoAH Completely Separated). Oculomotor scores were also significantly different for these two conditions, with lower scores associated with AH Dual Banners. The NoAH Completely Separated condition also had marginally higher oculomotor scores when compared to the Completely Separated display incorporating the artificial horizon (AH Completely Separated). There were no significant differences of sickness symptoms or severity (measured by self-assessment, postural stability, and cognitive and visual tests) between display designs 30- and 60-minutes post-exposure. Further, 30- and 60- minute post measures were not significantly different from baseline scores, suggesting that aftereffects were not present up to 60 minutes post-exposure. It was concluded that incorporating an artificial horizon onto the Dual Banners display will be beneficial in mitigating symptoms of motion sickness in manned ground vehicles using 360° indirect vision systems. Screening for perceived attentional control will also be advantageous in situations where selection is possible. However, caution must be made in generalizing these results to missions under terrain or vehicle speed different than what is used for this study, as well as those that include a longer immersion time.
2

Det perifera seendets betydelse bland gångtrafikanter i naturlig miljö / Peripheral vision and its importance amongst pedestrians in a natural setting

Björnqvist, Anton January 2019 (has links)
The importance, and the role, of peripheral vision amongst pedestrians, is an area which for a long time has remained unexplored. Previous studies regarding peripheral vision and pedestrians have mostly studied the characteristics of peripheral vision, the general visual behaviours amongst pedestrians and whether people affected by a natural loss of peripheral vision fixate on different objects compared to those with normal vision. To examine the role of peripheral vision amongst pedestrians, an experiment consisting of 20 participants was conducted. The experiment took place in a car park, where head movements (i.e. how many times each participant moved their head) and head directions (i.e. in which direction the participants’ moved their heads) of the participants were recorded using three action cameras. Two of the cameras were mounted on a helmet which the participants used during the experiment. The third camera was in the hands of the experimenter, recording the participants from behind. The experiment consisted of four different conditions. Two conditions where the participants’ peripheral vision was blocked to different extents, one with no manipulation of the visual field and one where the participants were told to watch a video on a cell phone during the walk. The results demonstrated a significant difference in the number of head movements between all four conditions. Furthermore, the results also demonstrated a significant difference in the relative frequency of downwards head directions between the first three conditions. After the experiment, the participants answered a short survey which included questions related to each condition. The answers from the survey showcased, amongst other things, that the participants thought that the condition where their peripheral vision was blocked to the largest extent was the most difficult one. A thematic analysis was conducted based on the recordings of a think-aloud-protocol which the participants were told to conduct during the experiment. The thematic analysis demonstrated, amongst other things, that the participants thought that the condition performed with no manipulation of the visual field was easy, that they felt insecure when their peripheral vision was blocked and therefore had to increase the number of head movements, and that they sometimes felt the need to redirect their gaze away from the cell phone during that condition. The conclusion which can be drawn based on the results is that the peripheral vision is widely used amongst pedestrians in natural settings, which in part is based on the fact that the participants increased their number of head movements when their peripheral vision was limited and by their own expressed thoughts regarding the different conditions. However, the results are not able to explain exactly how the peripheral vision is used amongst pedestrians. / Det perifera seendets betydelse och roll bland gångtrafikanter i naturlig miljö är ett område som till stora delar stått outforskat. Tidigare studier har främst fokuserat på uppmätning av periferins egenskaper, gångtrafikanters allmänna visuella beteenden samt studerandet av personer drabbade av naturligt synfältsbortfall. I syfte att undersöka det perifera seendets betydelse bland gångtrafikanter genomfördes ett experiment med 20 deltagare på en parkeringsplats, där huvudrörelser (d.v.s. hur många gånger varje deltagare rörde på huvudet) samt huvudriktningar (d.v.s. i vilken riktning deltagarna rörde huvudet) uppmättes med hjälp av två actionkameror fästa på en hjälm, samt en i handen på försöksledaren som filmade deltagarna bakifrån. Experimentet bestod av fyra olika betingelser, där två av dem blockerade det perifera synfältet olika mycket, en under normala synförhållanden samt en där deltagarna fäste blicken på en mobiltelefon under gången. Resultatet visade en signifikant skillnad i antalet huvudrörelser mellan samtliga betingelser. Utöver detta visades en signifikant skillnad i frekvensen av huvudrörelser nedåt vid en jämförelse mellan de tre förstnämnda betingelserna. Efter utfört experiment fick deltagarna dessutom svara på en enkät, vilken bland annat visade att deltagarna själva skattade att betingelsen där deras perifera seende blockerades som mest var svårast att genomföra. En tematisk analys genomfördes även baserat på data från ett tänka-högt-protokoll som deltagarna var uppmanade att föra under experimentets gång. Detta visade bland annat att deltagarna kände att det var enkelt att gå vid normala synförhållanden, att det fanns osäkerhetskänslor och behov av huvudrörelser vid betingelserna där periferin blockerades, samt att många kände ett behov av att lyfta på blicken vid mobiltelefonbetingelsen. Slutsatsen som kan dras baserat på resultaten är att det perifera seendet används mycket bland gångtrafikanter i naturlig miljö, vilket dels grundar sig i att deltagarna rörde som mest på huvudet när deras perifera seende blockerades, samt deras egna yttrade tankar. Det som inte kunnat besvaras är exakt hur det perifera seendet används bland gångtrafikanter.

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