虛擬實境眩暈症(Cybersickness / VR sickness)，指的是因為使用沈浸式虛擬實境裝置而造成的眩暈症狀。目前主要研究顯示，這樣的症狀源自於視覺狀態與身體的動態不匹配。類似的情況也發生在暈車、暈船等情況上。
目前科學上尚未明確歸納出容易產生眩暈的體質是如何，但根據此症狀產生的根本上，我們可以先推斷可能是來自兩個器官的交互作用，那就是掌控視覺的『眼睛』和掌握身體平衡的『內耳前庭系統』。而本次實驗，我們將專注在視覺能力指標，包含動態視力、深度知覺與Cybersickness之間的相關性。
在第一階段的實驗中受試者會被要求進行三項視覺能力的檢測，分別是眼電圖(Electrooculography, EOG)、動態視力以及深度知覺。第二階段受試者則會被要求觀看三個暈眩程度不同的虛擬實境影片，研究使用之VR設備為HTC Vive Pro 一級玩家版。
第一階段部分，使用網路軟體紀錄完成任務的秒數作為動態視力指標，使用Randot Stereo Test紀錄最後正確辨識的秒角(Arc)作為深度知覺指標。接著黏貼EOG於眼角四周，獲取眨眼頻率以及眼球運動軌跡的資訊，與第二階段實驗同步進行。實驗設計之依變數(Dependent variable)為SSQ(Simulator Sickness Questionnaire , SSQ)以及其進階數據三類別分數噁心Nausea (N)、眼動Oculomotor (O)、迷失方向Disorientation (D)，將與動態視力指標、深度知覺指標、眨眼頻率以及凝視時間等四自變數(Independent Variable)進行迴歸分析。
實驗結果證實了所挑選三部影像內容在誘發Cybersickness 的程度上有顯著差異，且各類別分數呈現 (D) > (O) = (N)的趨勢。動態視覺能力指標如預期在暈眩等級最高的情境3出現高度相關，證實兩者間是有直接關係；深度知覺能力則未發現顯著相關性，推測原因是單純透過Randot Stereo Test測量之秒角不足以代表個體之眼球聚散、調節能力，需收集更多客觀量測數據如眼球轉動速度、角度。眨眼次數在三個情境下並無顯著差異，顯示在短期的虛擬實境刺激下眨眼模式仍遵循個人眨眼模式，但在暈眩等級最高的情境3中眨眼次數與受試者的SSQ問卷分數顯著較高，符合預期結果；凝視時間部分在情境1及情境2中無顯著差異，在情境3中則顯著提升且達到高度相關，可以做出結論是凝視時間在誘發cybersickness的情況下會顯著增加。
以本實驗之結論延伸，後續研究可分為兩個方向，分別是細究本研究成果，以及如何應用本研究之成果於改善Cybersickness 之程度。前者部分，可以透過量測眼球轉動角度、用更精準的眼動儀器量測實時眼動狀態等方式，完成本研究對於深度知覺能力以及凝視時間方面的實驗假設。再來是可以加入更多時間序列的研究來了解整個症狀發生的進程。後者部分，則可往如何幫助先天動態視覺能力較差者適應虛擬實境內容的方向思考。使用者瞭解暈眩的成因後，即可加以調整或避免。

Cybersickness is defined as the symptom of dizziness and uncomfortable due to immersing in the virtual reality (VR) environment. Previous study indicates that the symptom is mainly caused by the mismatched information between visual information and actual body status. Similar situation also appears on motion sickness when people are on a moving vehicle. Now we don’t have the specific feature of people who tends to be easier to occur Cybersickness, but we can assume that the feature appears on either the visual part or the vestibule of inner ear system, which is in control of body balance. For this study. We’ll focus on the visual part.
For the first part of this study, participant will be asked to do three types of visual ability examination, they are respectively EOG, Dynamic vision and three-dimensional ability. The second part participant are asked to watch three VR content video at different dizziness level. The VR equipment we’ll use is the HTC Vive Pro generation 1.
For the first part, we use a web tool to record time that participant finish the task as the indicator of dynamic vision, use Randot Stereo Test to record the last successfully identified picture as indicator of three-dimensional ability. Then we use EOG to collect data of eyeblink frequency and eye movement, this part will synchronize with the second part of the experiment, the virtual reality environment test.
The design of this experiment consists of SSQ Score and its 3 categories score (N), (O), (D) as the dependent variables, while Dynamic vision, three-dimensional ability, eyeblink frequency and fixation time are the four independent Variable to perform the regression analysis. In the end, we make conclusion for this study and discussion for future work.
Result of the experiment shows that the 3 video we chose do have significant difference on the severity of Cybersickness, and the trend of three categories goes by (D) > (O) = (N). Dynamic visual ability indicator and the SSQ score in situation 3 is highly correlated as expected, it’s clear that the 2 indicators have direct relationship. On the other hand, there is no significant correlation between depth perception indicator and the SSQ score in each situation, varies from our expectation. We assumed that it’s because the Arc we collected from Randot Stereo test is not representative enough for personal vergence and accommodative response ability, need to collect more objective data such as eye rotation angle, speed to complete the assumption. Eye blink rate have no significant difference in three situations, shows that under short-term VR stimulation the eye blink rate still follow personal’s eye blink pattern. However, in situation 3 which causes severe cybersickness, eye blink rate is significantly correlated with SSQ score, proofed the assumption. Fixation time have no significant difference in situation 1 and 2, in situation 3 the average fixation time significantly increase and highly correlated with SSQ score. We can conclude that fixation time significantly increase when cybersickness is triggered.
To extend from the study’s result, future research can be split into two directions. First is to look into the result and use more objective measurement, eye-movement tracker, real-time analysis to strengthen and complete the hypothesis. Second is on how to help those who is born with worse dynamic visual ability to fit into Virtual reality. we already realize the cause of dizziness, the future work is to find out how to adjust and avoid the symptom.

Keywords: Virtual Reality, Cybersickness, Dynamic vision, Three-dimensional ability, Electrooculography (EOG)

摘要------------------------------------I
ABSTRACT------------------------------III
目錄 --------------------------------V
圖目錄--------------------------------VIII
表目錄-----------------------------------X
第一章 緒論------------------------------1
1.1研究背景與動機------------------------1
1.2研究目的與範圍------------------------3
1.3實驗假設------------------------------5
1.4 研究架構與流程------------------------6
第二章 文獻回顧---------------------------7
2.1 VR設備規格及實際應用------------------7
2.1.1 市售VR虛擬實境穿戴裝置介紹及規格差異-10
2.1.2 小結------------------------------11
2.2 CYBERSICKNESS之成因及特徵------------11
2.2.1 CYBERSICKNESS的症狀----------------12
2.2.2 生理數值特徵-----------------------12
2.2.3 影像內容特徵------------------------15
2.2.4 減緩CYBERSICKNESS 策略-------------18
2.3 CYBERSICKNESS 之衡量標準--------------19
2.3.1主觀問卷認定 (SSQ)-------------------19
2.3.2 改良版問卷 (CSQ)--------------------22
2.3.3 腦波訊號量測 (EEG)------------------24
2.3.4 小結-------------------------------24
2.4 視覺調節能力--------------------------26
2.4.1 動態視力檢測------------------------26
2.4.2 深度知覺測試------------------------27
2.4.3 眼電圖(EOG)-------------------------33
2.4.4 小結--------------------------------36
第三章 研究方法----------------------------37
3.1 研究對象-------------------------------37
3.2研究工具--------------------------------38
3.3 實驗流程-------------------------------43
3.4 數據分析-------------------------------47
3.5統計分析------------- ------------------53
3.6 前置測試-------------------------------54
第四章 實驗結果-----------------------------57
4.1 SSQ問卷分數統計結果----------------------57
4.2 SSQ分數噁心NAUSEA (N)、眼動相關OCULOMOTOR (O)
及迷失方向DISORIENTATION (D)三者之進階分析----58
4.3動態視覺能力之強弱與SSQ分數之相關----------60
4.4 深度知覺能力之強弱與SSQ分數之相關---------63
4.5 眨眼次數之高低與SSQ分數之相關-------------65
4.6 凝視時間長短與SSQ分數之相關---------------70
第五章 討論----------------------------------74
5.1 誘發CYBERSICKNESS 之影片特徵--------------74
5.2 SSQ問卷結果探討------------- ------------75
5.3 各項視覺能力指標與SSQ分數之相關性----------76
5.4 研究限制---------------------------------79
第六章 結論與未來方向--------------------------81
參考文獻--------------------------------------83
附錄 研究倫理審查通知書------------------------92

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