Stroop作業中不同歷程的排程問題：以計畫排程之要徑法(CPM)為分析工具所推論的結果

Scheduling of Mental Processes in the Stroop task with Critical Path Method

本研究採用計畫排程法中之要徑法（CPM）來對Stroop作業中的認知歷程進行探討。實驗一與實驗二為重複Schweickert（1983）的實驗（但刺激字以中文呈現）。在實驗一「叫字」作業結果顯示，受試者對於「顏色」和「字」的認知模型為次序性，「顏色」會被先處理。而實驗二「叫色」作業中，所獲致的結果和Schweickert叫色作業的分析結果一致。受試者對於「顏色」與「字」的認知模型為惠氏登橋式，「字」會先被處理。上述兩個實驗結果也呈現出受試者會先處理無關的刺激。實驗三與實驗四以相同的實驗設計方式操弄，但讓受試者自行決定其反應順序，實驗所獲致的結果卻和Schweickert（1983）的結果有很大差異。首先，在兩個實驗中都顯示，「字」的刺激都是先被處理。本研究針對不同的認知模式一次序性、惠氏登橋式一之可能決定因素，提出解釋與說明；並針對兩作業瓶頸的所在位置，提出推論的證據。根據分析的結果，受試者似乎會依據作業的難度、刺激與反應的相容性等因素來決定認知模式；此外，分析結果也顯示瓶頸似乎是發生在反應決策階段與反應產生階段。

Schweickert (1983) employed the Critical Path Method (CPM) to study the mental processes underlying the Stroop task. In both the color naming and the word naming tasks, the participants were asked to make two responses, the manual one to the irrelevant dimension and the vocal one to the relevant dimension. The manual response was always to be issued first. The author found that in the color naming task, the word was processed first, whereas in the word naming task, the color was processed first. The results were taken as a challenge to the major account of the Stroop effect, which maintains that the word is automatically processed first. We hypothesized that Schweickert's results were due to the author's artificially imposing the manual-first response order in their participants. To test this hypothesis, we first replicated Schweickert's experiments using the same procedures (Exp. 1 & 2). Next, we repeated the same experiment, but leaving the participants to decide on their preferred response order (Exp. 3 & 4). The results obtained from Exp. 1 and 2 were similar to Schweickert's. By contrast, the results of Exp. 3 and 4 showed that the word was always processed first regardless of the task. It was also found whether the dual processes took the form of a serial order or of a Wheatstone Bridge depended on the difficulty of each task and their combination. Specifically, when both tasks were easy, a serial process seemed to be in effect, whereas when one of the processes was hard enough, the coordination of the two process turned into the form of a Wheatstone Bridge. We discuss why this might be so.