| 摘要: | 本研究結合項目指示遺忘程序(Item-method Directed Forgetting)與詞彙判斷作業(Lexical Decision Task)，比較受試者意圖記憶或是遺忘促發項時，對隨後出現之目標項的行為反應以及電生理訊號之影響，藉以探討主動遺忘歷程是否牽涉抑制的歷程。在學習階段的每個嘗試中，受試者分別對促發項以及目標項做詞彙判斷，當促發項及目標項皆為真詞時，二者之間可為語意相關或是語意無關。要求受試者記住/忘記促發項的線索(R/F cue) 則出現在促發項呈現完畢之後，目標項呈現之前。實驗一為行為實驗，以受試者間變項的方式操弄R/F cue呈現時間的長短，分別為500毫秒、1500毫秒和2500毫秒。在測驗階段採用自由回憶測驗，要求受試者盡量回憶出先前在學習階段看過的促發項項目，無論原先是要求受試者記住或是忘記該促發項。實驗一的結果與Marks與Dulaney(2001)的研究相符，受試者對語意相關目標項的反應時間短於語意無關的目標項，得到顯著的語意促發效果，然而這樣的促發效果並沒有隨著目標項之前的線索是R cue或F cue而有所不同，且無論該目標項與促發項是語意相關或語意無關，受試者對跟隨在R cue後之目標項的反應時間都比跟隨在F cue後之目標項的反應時間更長。實驗二(R/F cue呈現500毫秒)與實驗三(R/F cue呈現1500毫秒)中紀錄受試者在學習階段時的ERPs，探討N400效果是否會隨著R/F cue而有所不同。實驗結果發現，在相當早的ERP波形上就發現線索呈現時間長短的效果，例如N170的大小受到注意力資源的充裕與否所影響，此一結果與Marks & Dulaney(2001)不同作業轉移耗損的資源量不同之推論一致。到目標項出現200毫秒左右時，開始進入詞彙處理的早期階段，但由於注意力資源短少且仍被覆誦歷程佔用時，則會發現P200只在線索呈現時間短的狀況下會受到線索類型的影響。然而這些認知資源的充裕與否對於目標項的處理程度並無顯著影響，受試者仍能將目標項處理到語意程度，無論實驗二、實驗三或線索類型為何，皆得到語意無關目標項引發較大之N400的結果，然而只有在線索呈現時間短時發現N400效果隨著線索類型而有不同的頭皮分佈，顯示在某些情況下，要求去記住或忘記某一項目時，的確會引發受試者對TBR與TBF項目有不同的處理歷程。This study incorporated item-method directed forgetting with lexical decision task, a paradigm developed by Marks and Dulaney (2001), to investigate whether the Remember/Forget instruction modulates the processing of the subsequently presented target words. At study, subjects made consecutive lexical decisions to the prime and target, each comprised two Chinese characters. In trials that both prime and target were real words, they were either semantically related or unrelated. A Remember/Forget/Neutral cue, instructing subjects to remember or to forget the prime, was presented after the offset of the prime but before the onset of the target. In Experiment 1, the duration of the cue was manipulated. At test, subjects recalled all study items (both R-cued and F-cued prime words). A semantic priming effect, i.e., faster RTs to related targets in comparison to unrelated targets, was observed. However, this priming effect was of similar magnitude for targets preceded by Remember and Forget cues, and was not modulated by the duration of the Remember/Forget cues. In addition, across related and unrelated targets, the RTs were longer when the targets were preceded by a Remember cue than a Forget cue. In Experiments 2 & 3, across which the cue duration was manipulated, ERPs were recorded the study phase. A reliable N400 effect, thought to index semantic processing, was observed when comparing related and unrelated targets, whether or not the targets were preceded by a Remember or a Forget cue. Nevertheless, the scalp distributions of the N400 effect following the Remember and Forget cues were different when the cue duration is short (experiment 2), suggesting that the neural substrate for the two sets of N400 effect do not fully overlap. It suggests that the instructions to Remember and to Forget indeed elicit qualitatively different cognitive processes upon the processing of the TBR and TBF items. |
