「注意力作用有無」與「訊息處理時間長短」的區分

Abstract

在視覺處理的歷程中，需要注意力的歷程向來被認為是比較花時間；而不需注意力的歷程則是比較快速的。本研究使用兩系列分別採取質地區隔以及賽門作業的實驗，來檢驗上述假設。方法上，本研究採取「不注意派典」：實驗的關鍵刺激在背景中，與受試者的主要作業無關，在這種受試者的注意力不在背景的關鍵刺激的情況下，觀察背景的關鍵刺激對於受試者的行為有何影響。實驗一A與實驗一B發現：即使受試者無法察覺背景中經由質地區隔所定義出的刺激，但對於前景的線段判斷作業卻受背景的影響。然而這樣的影響只發生刺激時間呈現為500毫秒而非200毫秒。因此，質地區隔可以不須注意力即達成，但需要比較長的時間。實驗二A與實驗二B發現：背景刺激是否導致賽門效果，取決於受試者的注意力是否在背景刺激上，與刺激呈現時間無關。結合這兩系列的實驗，我們認為：注意力是否作用以及訊息處理時間長短兩者可以是獨立的因素，對於不需要注意力的歷程而言，它發生的時間可快可慢，取決於刺激本身的特性；對於需要注意力的歷程而言，它發生的時間也可快可慢，取決於注意力是否介入。

Visual processing without attention is often assumed to be fast, and with attention it is usually assumed to be time-consuming. We argue against such a conventional view by showing that processing time and attentional operation can be dissociated. In two pairs of two experiments each, we used texture segregation and the Simon task to demonstrate this point. By adopting the inattention paradigm in all four experiments, whether a given process occurs under the condition of inattention is inferred from the extent to which the participant’s performance is affected by the undetected background stimulus. In Experiment 1A and 1B, we found that although the participants were unaware of the background patterns defined by texture segregation, the performance of the line length judgment of the foreground stimuli could be affected by the background. However, this occurred only when the exposure duration was 500 ms but not when it was 200 ms, showing that texture segregation can occur inattentively but it takes time. In Experiment 2A and 2B, we found that attention rather than processing time is necessary for the occurrence of the Simon effect. We thus conclude that attentional operation and processing time should be dissociated. For the inattentional process, it might be fast or slow depending on the properties of the stimuli; for the attentive process, it might also be fast or slow depending on whether or not attention is deployed on the stimuli.