三維立體視覺刺激於穩態視覺誘發電位之研究

Abstract

腦機介面（brain-computer interface, BCI）通常被認為是一個讓重度殘疾人士能與外界溝通非常實用的方法。為了使腦機介面具有更廣泛的應用，所以我們將腦機介面與立體液晶顯示器（liquid crystal display, LCD）結合。如此，可以擴大顯示器的應用和為人們的日常生活帶來更大的便利。除此之外，比起傳統的平面顯示器，立體顯示器可以提供更多種類的視覺刺激，所以將立體視覺刺激應用於的穩態視覺誘發電位 (steady-state visual evoked potential, SSVEP)為基礎的腦機界面基礎是具有前瞻性的。而本研究的目的主要是在不同條件的立體視覺刺激下，主要變因包含了視差角度 (disparity angle)及影像互擾(crosstalk)，是否會對穩態視覺誘發電位信號有不同的影響。此實驗共有十二位受測者參與實驗，其中為兩名女性及十位男性，年齡介於22至28歲。在實驗過程中，他們僅需凝視著由3D偏振式顯示器所產生的刺激，且不同參數的刺激是隨機出現。 而實驗結果為在不同的視差角度底下，穩態視覺誘發電位的訊噪比(signal-to-noise ratio, SNR)，僅在大角度與小角度間有顯著的差異（p值< 0.05），且在不同程度的影像互擾底下，卻沒有顯著的差異（p值> 0.05）。除此之外，我們探討受測者觀看立體視覺刺激時是否合成，來觀察是否對穩態視覺誘發電位的信號有影響。結果得到當受測者觀看有合成的刺激時會有較大的訊噪比比起無法合成的刺激，且此結果經由統計方法計算是有顯著差異的（P值 <0.05）。

Brain-computer interface (BCI) is often considered to be a very practical way to allow severe disabilities communicate with the outside world. To make BCI have broader applications, we want to combine the BCI and stereoscopic liquid crystal display (LCD). This can expand the application of display and improve the convenience of our daily lives. Stereoscopic display can provide more different visual stimulation, so stereoscopic stimulation SSVEP-based BCI is forward-looking. The purpose of this study is to investigate the SSVEP signal to the stereoscopic stimulation in different condition including disparity and crosstalk. Twelve participants (2 females) ranging in age between 22 to 28 years old participated in the experiment. They stared the stereoscopic stimulation generated by a polarized 3D display. The experiments were conducted in a counterbalanced order. The results showed that there are significant difference (p-value<0.05) between large and small disparity angle. There are no significant difference (p-value>0.05) between different crosstalk. Moreover, we investigate the SSVEP in different situation that participant’s stereopsis perceived or unperceived. The result is that perceived is larger than un-perceived in the SNR of SSVEP response, and there is a significant differences (p < 0.05) were observed.