輻射狀構圖對視覺注意力分佈的影響

Abstract

摘 要 在從事設計繪畫工作時，設計人員都會運用適當的構圖形式，將圖像作有效的選擇與安排，其目的是希望觀看作品時能產生較多的注意力在畫面中強調的重點或是焦點位置上。而在許多的設計繪畫書籍中經常提到，輻射狀構圖的放射線所形成的集中焦點，常被視為最有效的畫面視覺中心，這類的構圖多半具有透視圖法的暗示作用，容易表現明顯的遠近感以及動態效果，並且能在繪畫的空間中運用圖像來引導出畫面中的焦點位置，獲取觀看者的注意力，也因此大量的被運用到不同形式媒體的平面設計中。本研究以輻射狀構圖的注意力判斷作為研究主題，來驗證輻射狀構圖所形成的集中焦點是否能讓觀看者投注較多的注意力資源在集中焦點上。主要探討的操弄變項包括集中焦點的位置以及輻射狀圖像出現的刺激間距。研究中將實驗的圖像分成沒有輻射狀構圖的控制組以及有輻射狀構圖的實驗組，測試畫面中不同點的位置，藉由量測注意力集中在畫面中的某一點時，所獲得的注意力反應時間長短，來探討輻射狀構圖對注意力的影響大小。研究的結果發現：(1)輻射狀構圖所形成的集中焦點位於畫面中心比不位於畫面中心時，能獲得較多的注意力分佈；(2)當圖像刺激間距在100ms與500ms時，受試者在集中焦點能有較多的注意力分布，而當圖像刺激間距在2000ms時則與沒有輻射狀構圖的控制組沒有差異，意謂著集中焦點在觀看的瞬間能獲得較多的注意力，但注意力會隨著觀看時間的增長而擴散分佈；(3)不論集中焦點在畫面中的位置為何，當輻射狀圖像的引導作用強烈時，注意力的分佈會以集中焦點而逐漸往輻射狀圖形發散的方向遞減。

ABSTRACT Composition is the means used by a designer or a painter to manipulate the viewer’s visual attention on a picture. An effective usage of composition involves directing the viewer’s scanning path to a specific point of interest. Among the commonly used composition forms, the radial composition is considered as the most effective way to guide a viewer’s attention by many authors. This thesis examined whether a viewer’s attention is indeed automatically drawn to the focal point of a radial form. We measured the viewer’s reaction time (RT) for detecting a target at various locations on the screen. The RT is taken as an index to the amount of attention paid to a given spot on the screen. The participants were asked to detect a target on the screen as fast as possible at the presence of a radial pattern background. To trace out the temporal dynamics of the viewer’s spatial attention, the onset asynchrony between the target and the radial background was manipulated on three levels: 100 ms, 500 ms, and 2000ms. The position of the radial focus is either at the center or off center of the screen. All RTs obtained in the experimental conditions are compared with those obtained with a blank screen (the control condition). Our results show that: (1) The focal point of a radial form does attract a viewer’s attention, especially when the radial form is positioned at the center of the screen. (2) The attention-capturing effect only lasts till about 500 ms after the onset of the picture. At 2000 ms after the onset of the picture, there is no measurable attention-capturing effect. (3) The attention-capturing effect shows evident spatial gradient peaking at the focus of the radial form and dies away gradually with distance.