過去研究顯示情緒性的記憶與非情緒性記憶在正確率與清析度上皆有顯著的不同，但這些結果多在探討情緒性記憶的形成機制，較少著墨於相關的控制歷程，例如記憶的抑制或搜尋。因此本研究將探討在不同的情緒情境下進行記憶登錄，會如何影響記憶的形成與提取. 實驗一採用項目指示遺忘作業，並操弄入碼階段的情緒情境。結果顯示當指示受試者主動記住(To-Be-Remembered)中性目標時，負向的入碼情境會妨害其記憶表現，但此種情緒操弄並不影響主動遺忘(To-Be-Forgotten)的抑制表現。事件相關電位(ERP)則顯示相較於中性的入碼情境，在負向的入碼情境下，需要主動記住的目標項目會引發較為延長的P3b波形。因此推測情緒性的入碼情境會影響記憶形成時的精緻處理(elaboration)。實驗二意在以磁振造影技術檢測當試圖提取在不同入碼情境下形成的記憶時，記憶提取導向(retrieval orientation)相關的腦部活動是否會有所不同。影像結果顯示角回(angular gyrus)、顳葉中回(middle temporal gyrus)、以及額葉中回(middle frontal gyrus)等區域的活動，在搜尋記憶時皆會受到記憶形成時的情緒經驗影響，因此推測提取情緒性的記憶會需要較多對於內在訊息的注意控制。實驗三以記憶提取導向作業檢測憂鬱症患者提取情緒性記憶的歷程與健康受試者是否有所不同。事件相關電位的結果顯示相較於對中性記憶的提取導向處理，憂鬱症患者對負向經驗的提取會在頭殼側邊引發較大的效果波形，而健康受試者所引發的效果則集中在中央頂葉區域。這可能暗示了憂鬱症患者對於負向情緒記憶的提取，可能涉及與健康者不同的腦區活動。;Emotional memories are often viewed as distinct from non-emotional memories in terms of content as well as the accuracy and vividness. Although numerous studies have focused on the mechanisms of emotional memory, few have examined the control processes related to memory formation and searching. Thus, in the current thesis, the effect of emotional encoding context on memory control processes in the encoding and retrieval phases is studied.
The first experiment adopted the item-method directed forgetting task with emotional or non-emotional contexts. The results indicated that emotionally negative encoding context impaired elaborative encoding for the to-be-remembered (TBR) items rather than intentional forgetting for the to-be-forgotten items. The event-related potential (ERP) data showed a prolonged P3b waveform that was related to intentional encoding to the TBR cue. Therefore, emotional context during encoding may impair the control processes of intentional elaboration for memory items.
The second experiment examined the effect of emotional encoding context on retrieval orientation, which involved searching and cue processing according to retrieval demands. Although no significant behavioral effect was noted, functional magnetic resonance imaging data showed that during retrieval, activity in the angular, middle temporal, and middle frontal gyri was related to the emotion of the retrieved memory, implying that the attempt to retrieve emotional memories may involve greater attention control over internal information.
The third experiment used the retrieval orientation task to examine whether the retrieval process for negative memories differs between patients with major depressive disorder (MDD) and healthy participants. The patients with MDD showed a greater ERP effect over the lateral area when retrieving negative memories, whereas the healthy individuals demonstrated an effect over the middle parietal scalp area. This result implies that neural activity involved in searching for negative memories may differ between patients with MDD and healthy individuals.
