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| 2009/05/28 10:46:04瀏覽2467｜回應0｜推薦8 | |
| 來源：科學網 利用簡單的虛擬現實技術，科學家刻意欺騙了人們的大腦，使他們產生了少有的體外經歷（out-of-body experiences）和自覺意識（Self-Consciousness），即一個人能夠感受到他正在從自己的身體之外“看到”自己和周圍環境。這一研究成果揭示了人類大腦在整合各種感官信息的過程中是如何產生混亂的。相關論文發表在《科學》雜誌上。 盡管這種“靈魂出竅”的經歷往往是唯心論者所宣揚的，但是，新的兩項獨立的科學研究表明，通過簡單的伎倆就可以輕易欺騙我們的大腦。在每項實驗中，參與者都戴著一副虛擬現實眼鏡，它與一臺對準參與者自身的攝像機相連。在英國倫敦大學學院 Henrik Ehrsson領導的實驗中，研究人員在將一根刺移入攝像機鏡頭的同時，準確地在參與者的胸部刺了一下。在這種情況下，參與者很強烈地認同了攝像機中的場所，並且認為他們自己的位置就處於那裏。而且，這種感覺與他們平常觀看其他人並無二異。 在另一項由瑞士聯邦技術研究院（Swiss Federal Institute of Technology）Olaf Blanke領導的實驗中，一些病人通過眼鏡看到他們背部被擊打的同時，背部也真的被打了一下。參與者同樣對正處於畫面中的位置表示了強烈的認同。 Ehrsson表示，人們通常感受到自己處於身體之內，不過，新的實驗設計讓大腦所得到的信息與這種通常觀念不符，才發生了體外經歷。他說，“大腦會騙自己，因為它要讓各種感官信息變得有意義。如果這些信息是有缺陷的，那麽它就會產生錯誤的認識。” 盡管在現實世界中，人們無法直接看到自身，但在某些人的想象中，他們的身體可能處於思維和精神之外。Ehrsson和Blanke懷疑，這種幻想的出現可能源於特定大腦區域的故障，比如整合感官信息的大腦顳頂皮層（tempoparietal cortex）。 新的研究將有助於科學家開發更有現實感的計算機模擬和遠程遙控系統，並且加深對精神分裂癥等疾病患者大腦活動的理解。Ehrsson表示，“如果你能感受到你就處於遠程遙控另一端的位置，那麽你的行為動作將變得直觀得多。” 英國倫敦大學研究人員利用虛擬現實裝置成功完成了一項“靈魂出竅”實驗。據日本共同社援引美國《科學》雜誌的報道稱，被實驗人感到自己的靈魂離開了肉體，並從外部觀察著自己的身體。 一直以來人們都認為“靈魂出竅”的感覺來自單純的想像，但該實驗將有可能幫助我們科學地解釋這一感覺。 倫敦大學的亨裏克·艾森(音譯)博士讓健康狀況良好的被實驗人坐在椅子上，並在其後方2米處安放攝像機，用來拍攝其背部姿態。然後再讓被實驗人戴上一幅特殊的眼鏡，通過該眼鏡中的屏幕，被實驗人能看到攝像機拍攝的圖像。 在攝像機前上下揮動棍子，同時用棍子接觸被實驗人胸部並作相同動作後，多數被實驗人都回答說，感覺自己的身體位於攝像機前方，自己好像是在從後面看著別人一樣。 在體驗這一環節後，研究人員又用一把錘子向攝像機揮去，被實驗人都做出了感到恐懼的神經反射。這可以解釋成被實驗人感覺自己的身體處在攝像機前而做出的反應。 艾森博士指出：“在視覺和觸覺被分離後，大腦的感官信息處理變得混亂，於是大腦創造出一個幻覺，使人感受到了一具並不真實存在的身體”。 “靈魂出竅”通常被認為是瀕臨死亡或神經受損的人才會出現的幻覺，有時甚至被貶為一種“迷信說法”。但美國《科學》雜誌刊登實驗報告說，科學家利用虛擬現實裝置，在健康人身上模擬出“靈魂出竅”現象，實驗對象感到自己的靈魂離開了肉體，並從外部觀察著“自己”。 模擬“出竅”  科學家進行的新實驗讓參與者感受到“靈魂出竅”：“我看到了我的存在。”  由瑞士洛桑埃科勒聯邦理工學院神經科學家奧拉夫·布蘭克博士和瑞典卡羅琳學院神經科學助理教授亨裏克·埃爾松博士分別率領的兩個研究小組，先後在健康人身上完成類似“靈魂出竅”的模擬實驗，使實驗對象在清醒狀態下看見幾米之外“另一個自己”。 在布蘭克的實驗中，實驗對象戴上虛擬現實眼鏡，能看到一個跟自己穿衣打扮一模一樣的模型。研究人員同時用棍子敲打實驗對象和模型，實驗對象感到疼痛的同時，還能看到“另一個自己”也被敲打，於是產生錯覺，以為自己的靈魂“附著”到模型身上。 然後，研究人員把實驗對象帶離原來的立足點，摘掉眼鏡後要求他們找到自己原來的位置，但他們都站到實驗中模型被放置的位置，也就是說，他們直接把模型當作“自己”。 埃爾松的實驗則連模型都不需要。實驗對象坐在屋子中間，身後約１．８米處放置有攝像機。通過連接攝像機的虛擬現實眼鏡，實驗對象能看到攝像機拍攝的自己背部畫面。 研究人員用棍子敲打實驗對象約２分鐘，同時通過拍攝畫面讓他們看到自己被敲打。在體驗這一環節後，埃爾松隨後在攝像機前舉起錘子，作出要落錘的樣子，實驗對象立即作出感到恐懼的神經反射，感到“另一個自己”正遭受錘子威脅。 視觸分離 研究報告說，“靈魂出竅”實驗成功的關鍵在於，被實驗者的視覺和觸覺被分離並錯位。 “我們利用虛擬現實，使視覺和觸覺接收的信息相互分離，”布蘭克接受路透社電話采訪時說，“兩種感覺因此發生錯位。” 埃爾松則指出，在視覺和觸覺被分離後，大腦的感官信息處理變得混亂，“於是大腦創造出一個幻覺，使人感受到一具並不真實存在的身體”。 美國普林斯頓大學神經科學助理教授馬修·伯特維尼克博士說，這兩項實驗表明，人之所以會產生“靈魂出竅”的感覺，實際上是因為視覺、觸覺、平衡感、方位感等多種感官接受的信息流互相錯位。 在此之前，“靈魂出竅”通常被認為是某種非現實力量作用的結果，或與所謂“瀕死體驗”或神經性損傷有關。 成果應用 瑞士蘇黎世大學醫院神經病學家彼得·布魯格說，兩項實驗為曾被認為神秘莫測的“靈魂出竅”現象提供了科學解釋，在弄清大腦如何感知問題上邁出第一步。 研究報告說，這一實驗成果不僅有助於解釋圍繞意識的一系列哲學問題，還能應用在更為實用的領域，如電腦遊戲、遠程外科醫療等。 埃爾松說，實驗成果的應用可能使外科醫生在進行遠程手術時，對手術室內環境產生觸覺，從而更好地通過視頻控制機械臂實施手術。 “最理想的情況是，（醫生的）‘自我’被完全搬到手術室中，”埃爾松說，“這項實驗將有助於達到那種境界。” 《自然》在線報道全文： Illusion mimics out-of-body experiences Scientists have deliberately fooled people into feeling they are watching themselves from outside their own bodies, using virtual-reality technology. The achievement reveals how the brain can be confused as it struggles to integrate confusing information from the different senses. People who claim to have had out-of-body experiences (OBEs) — most famously patients on the operating table or those who have narrowly avoided death — describe a sensation of having floated out of themselves, for example towards the ceiling of an operating theatre. From there they watch their body and activities surrounding it. Such experiences have been claimed by spiritualists to represent evidence of a soul. But the new research shows that it is possible to create a similar sensation simply by tricking the mind. Understanding how the mind sometimes perceives itself as journeying out of the body could help with the development of more realistic computer games or remote robotic systems, or even help to understand the brains of those who claim to experience the phenomenon naturally, such as schizophrenics or epileptics. You, me, me, you The effect was created in two separate experiments described in Science1,2 this week, both of which used a simple method to fool volunteers into thinking that their minds had been displaced outside their bodies. In each case, participants wore virtual-reality goggles hooked up to cameras trained on their own bodies. In one study, carried out by Henrik Ehrsson at University College London, volunteers were then prodded in the chest at precisely the same moment that an object approached the camera. In this scenario, the volunteers identified strongly with the location of the camera, thinking that this is where their true self was — the view of their body was like a view of someone else. In the other experiment, led by Olaf Blanke of the Swiss Federal Institute of Technology in Lausanne, patients viewed a camera image of their own back being stroked, while their own back was stroked too. In this instance, volunteers identified strongly with the picture of their back, thinking that this was their location - again outside their own body. Too much information The bizarre effect happens because, although we usually perceive ourselves to be within our bodies, the experimental set-up meant that the sensory information being supplied to the brain did not fit with this idea, Ehrsson explains. "The brain can trick itself internally because it is always trying to make sense of information — if that information is flawed or erroneous, it could come up with the wrong interpretation." The method does not recreate the 'classical' OBE — most strikingly because in the real-world setting, there's no obvious way for a person to 'see' themselves. But people could perhaps draw on their own mental body image to create the effect, says Ehrsson. "In the operating theatre there is no mirror on the ceiling, but there could be a 'mirror' in the head," he says. Ehrsson and Blanke suspect that this illusion might involve some sort of malfunction in brain regions such as the tempoparietal cortex that integrate sensory information. Nevertheless, "this new experiment has at last brought OBEs into the lab and tested one of the main theories of how they occur", comments Susan Blackmore, a psychologist at the University of the West of England in Bristol. "Finding out that OBEs are a perfectly natural phenomenon does not prove there is not astral body, or soul, or spirit, but it certainly makes their invention superfluous." Suspended disbelief The effect even works for plastic mannequins, as Blanke's team discovered when they replaced the subject's own image with that of a female dummy purchased for just 100 Swiss francs (US$83) (see video). But when they used a simple square of metal as the image, the OBE effect did not materialize, showing that the trick can only be stretched so far. Finding out exactly how much subjects can suspend their disbelief will be crucial in developing the technology to allow users to assume different personas, from remote robots to virtual-reality avatars, Blanke says. Using appropriate visual and tactile information to convey a feeling of operating in the body of a robot or virtual character could help with applications ranging from NASA's Robonaut project, which aims to control robots on the Moon, to surgeons performing operations over the Internet. "These applications could be improved if you could get the illusion that you really are in that place — you could act much more intuitively," Ehrsson says. |
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