視聽意義一致性、注意力及凝視點對雙穩定圖形知覺之影響

Abstract

雙穩定知覺指的是同一種刺激卻可以產生兩種知覺的現象。由於刺激維持不變，因此觀察者在知覺上的變化是來自意識上的變動，而非刺激本身。也因為有此特性，雙穩定圖形提供了意識研究一個很好的題材。過去的研究發現，一些有抽象意義的視覺圖片或文字敘述會影響雙穩定圖形的知覺。但是這些研究多著重在同一感官的刺激─視覺─對雙穩定圖形的影響。本研究主要探討一個有意義的聲會不會影響我們觀看雙穩定圖形的知覺，並探討聲音可能的作用方式。由實驗一我們可以看出，我們會偏向將雙穩定圖形知覺成與聲音意義一致的知覺，且此效果不是來自反應偏誤 (實驗二)。經由檢驗聲音與選擇性注意力的交互作用，我們發現當受試者選擇性的維持某一個知覺時，雖然降低了聲音的效果，但聲音仍然會影響觀看雙穩定圖形的知覺，因此推測聲音不是完全經由選擇性注意力來作用(實驗三)。而經由檢驗聲音與凝視點的交互作用可以看出，聲音對雙穩定圖形知覺的作用不受到凝視點位置的影響，推測兩者的效果應是獨立作用的(實驗四)。綜合所有的實驗結果，我們推測聲音對雙穩定圖形知覺的影響，，應是來自於跨感官知覺間的整合。一個在抽象意義上與視知覺一致的聽覺刺激，不同於過去研究所操弄的高階認知層次或低階刺激層次因素，在本研究中被驗證是另一種影響雙穩定圖形知覺的關鍵因素。

Bistable figures provide a fascinating window through which to explore human visual awareness, since a constant visual stimulus induces a dynamic alternation between two distinct percepts over time. Here we examine whether a background auditory soundtrack that is semantically congruent with either one of the percepts can modulate an observer’s perceptual state, and whether this auditory modulation interacts with selective attention and fixation position (factors that have previously been shown to influence the perception of bistable figures; Meng & Tong, 2004). We used the well-known bistable figure of 'my wife or my mother-in-law' as the visual stimulus, and presented the voice of an old or young lady as the background soundtrack. The results revealed that the participants reported seeing the old woman (or young lady) for more of the time when listening to the voice of an old woman (or young lady). Crucially, these results cannot simply be attributed to a consequence of response bias (Experiments 1 and 2). When the participants were instructed to voluntarily maintain a specific view, the crossmodal modulation of bistable perception was reduced in magnitude, but not completely eliminated (Experiment 3). Further, the auditory modulation was observed regardless of the manipulation of fixation position (Experiment 4). These results therefore demonstrate that auditory semantic context can modulate the visual processing of which a conscious percept emerges when viewing a bistable figure.