從「不可能」到「可能」：探討三維不可能物體的知覺推論與神經活動

Abstract

人類借助經驗比對接收到的感覺訊息，以處理眼花撩亂的世界，大腦做出的預測可加速此過程，但這樣的預測可能出現錯誤—錯覺。以往針對視錯覺相關之研究，多是以二維刺激材料進行，幾乎沒有關於三維錯覺之研究。日本數學藝術家—杉原厚吉教授，將二維錯覺轉換為獨特的三維不可能物體，使更深入的研究得以進行。藉由杉原教授提供的三維不可能物體（這些物體在鏡子前後擁有截然不同的兩個形狀），本研究以空間性向測驗挑選出30個物體作為刺激材料，並將物體拍攝成一系列之刺激影片，建立「鏡像辨識作業」及「知覺推論作業」，搭配腦電波來同步量測及探討其創造之不可能物體形成的預測錯誤之知覺訊號，以及知覺推論歷程的神經活動。根據鏡像辨識作業，當非預期的鏡像呈現時，腦波事件關聯電位及事件關聯頻譜震盪分析皆顯示可能的預測錯誤之相關信號，並且有類似情緒反應之晚期正電位。同時透過多元模式分析，知覺推論不同物體時的腦神經動態可以被分辨，且物體的複雜程度亦可影響其效果，而透過事件關聯電位分析得以進一步確認相關腦波成分分布。本論文以探索性之研究，強調錯覺相關知覺歷程之神經動態，開啟往後進一步探討三維錯覺實證研究之路。

We lean on matching sensory inputs with experiences to process the dazzling world. Our brain tends to make predictions to facilitate this processing; however, the brain could commit errors—illusions. In contrast to the various research on 2-dimensional (2D) optical illusory stimuli, there is hardly any empirical neural investigation of 3D authentic misrepresentation. Professor Kokichi Sugihara, a Japanese mathematician as well as artist, has turned the 2D illusions into 3D impossible objects, which allowed in-depth investigation into these intriguing perceptual field. Professor Kokichi Sugihara kindly provided the authentic 3D impossible objects whose appearance from the front view is incongruent with their reflection in the mirror. After conducting a spatial aptitude test to select 30 suitable 3D objects for this study, I created a set of video clips of authentic 3D impossible objects. Through the designed tasks: the peekaboo task and the perceptual inference task, I investigated the incongruent perceptions and the neural dynamics underlying the inference process of 3D illusion with the electroencephalogram (EEG). The result of the peekaboo task revealed significant differences between impossible objects and their counterparts in the time segment after the expected or unexpected sensory data inputs, which reflected the potential predictive error signals and also possible affective arousal. Applying multivariate pattern analysis (MVPA) to simultaneous EEG recordings, my result indicated that the impossible objects can be discriminated from the possible ones in the perceptual inference task, even between two configuration levels. With these exploratory results, this study highlights the neural dynamics underlying illusory-like perception and sheds the light on the sensory processing of these unique 3D impossible objects.