練習對作業轉換的促發效果

Practice Effects of the Priming Effects of Task-Switching

目前有一種假說認為轉換作業中的轉換虧損成因是由於前項刺激對後項刺激產生正向及負向促發作用使然。然而在一般的轉換作業中，前、後項刺激材料不盡相同。本研究的目的在於了解轉換作業中促發作用是作用在特定的刺激材料上，或是作用在整個作業操作的認知活動上？本研究的方法是要求受試者練習與轉換作業中的刺激項目完全不同、部份相同或全部相同的刺激項目。然後觀察練習不同的刺激項目之後的轉換虧損變化情形是否有所差別。結果發現練習完全不同及部分相同的刺激項目，所造成的轉換虧損變化情況不同於練習全部相同的刺激項目。這表示促發作用會受到練習與否的影響，而且該練習效果是作用在特定刺激項目上，而不是在整個認知操作上。

This study was to examine at what level that the priming effects of task switching may occur. One assumption was that the shift cost resulted from both positive and negative priming effects of the previous competing task-set. Accordingly, such priming effects should apply to a task ensemble. However, whether the priming effects come from item-specific priming or higher-order task-set priming remained to be explored. Our method to address this issue was to compare practice effects on shift cost among three conditions. The three conditions were that the subject had to practice identical items, practice subset of stimulus items and practice completely different experimental items. If the priming effects were item-specific, we should see a different change in shift cost after the practice between the conditions where the stimulus items were fully practiced versus where completely different items were practiced. Our experiment results confirmed this hypothesis.