年齡與長期記憶中抑制的時間歷程：提取練習典範與字彙語意促發效果的研究

Abstract

認知功能老化的可能原因之一為抑制能力的退化，認知抑制指為了避免對主要作業造成干擾，工作記憶或長期記憶中無關的資訊需被壓抑，讓它不會干擾在工作記憶中的認知作業。抑制可能發生在人類資訊處理的不同階段，過去的研究指出，年長者在抑制工作記憶中不相關的資訊上的能力與年輕人比起來較差。RIF指提取練習會引發相關記憶被抑制而暫時遺忘的現象。本研究藉由觀察在提取練習典範中是否有RIF及字彙判斷作業中的語意負向促發效果，來探討年輕人與年長者在抑制長期記憶中無關資訊上的差異。61名學生及61名63-86歲的年長者被隨機分配到200毫秒或1000毫秒SOA（字彙判斷作業中促發詞－目標字間的時間間隔）的情境。參與者在學習完48對類別－正例配對後，部分學習材料將接受額外的練習，最後以字彙判斷作業測量記憶。本研究僅在年長者200毫秒SOA時發現RIF，在1000毫秒SOA消失；然而年輕人無論在200毫秒或1000毫秒SOA皆無出現RIF或語意促發效果。結果顯示年長者在做字彙判斷時，無關的情節記憶會對目標作業形成干擾，因此無關記憶會被暫時的抑制。研究結果說明了年長者在自動抑制無關的情節記憶的能力以及激發目標的語意記憶的能力是保存的。

Inhibition is an automatic cognitive mechanism to prevent interference from irrelevant information unconsciously activated from the long-term memory. The purpose of this study was to investigate the age differences in the effect and the time course of inhibition with an implicit measure. Sixty-one older adults with age between 63 to 86 and 61 college students with age between 17 to 25 were randomly assigned to the 200ms or 1000ms SOA condition (the time interval between the onset of prime word and the onset of target word in the lexicon decision task) to study 8 categories of 6 single-character Chinese words. Three of studied words from four categories were given retrieval-practice before a lexicon decision task. Retrieval-induced forgetting was observed for the elderly at 200ms SOA, but disappeared at 1000ms SOA, whereas young adults did not show any retrieval-induced forgetting or priming effect at either 200ms or 1000ms SOA. Results suggested that older adults’ irrelevant episodic memory was a source of interference while making semantic judgement, and were deactivated temporarily through inhibition mechanism. These findings indicated that older people’s abilities to activate relevant semantic memory and to inhibit unwanted episodic information automatically remain intact with age.