Storing Trivial Memories Just in Case
儲存瑣碎記憶以防萬一
By Benedict Carey

The surge of emotion that makes memories of embarrassment, triumph and disappointment so vivid can also reach back in time, strengthening recall of seemingly mundane things that happened just beforehand and that, in retrospect, are relevant, a new study has found.
情緒猛然浮上心頭，尷尬的、歡欣的、失望的回憶，栩栩如生到彷彿回到當時，事發前看似平淡的事物在回憶強化後，回頭來看卻產生了關聯性，這是一項新研究的發現。

The findings, published recently in the journal Nature, fit into the predominant theory of memory: that it is an adaptive process, continually updating itself according to what knowledge may be important in the future.
最近登在期刊《自然》上的一些研究結果，符合記憶理論的通說：記憶是一個適應的過程，根據未來可能變得重要的知識而不斷進行自我更新。

The new study suggests human memory has, in effect, a just-in-case file, keeping seemingly trivial sights, sounds and observations in storage for a time in case they become useful later on.
新研究主張，人類記憶其實有一個以防萬一的檔案，保存各種看似瑣碎的視覺、聽覺和觀察經驗一段時間，以便日後需要時派得上用場。

But the experiment said nothing about the effect of trauma, which shapes memory in unpredictable ways. Rather, it aimed to mimic the arousals of daily life: The study used mild electric shocks to create apprehension and measured how the emotion affected memory of previously seen photographs.
但這項實驗沒有提到創傷的影響，創傷用無法預測的方式形塑記憶。相反地，這項實驗針對日常生活中的喚起予以模仿。研究運用輕微電擊製造疑懼，然後測量情緒如何影響對先前看過照片的記憶。

“The study provides strong evidence for a specific kind of retroactive enhancement,” said Daniel L. Schacter of Harvard University, who was not involved in the research.
沒有參與前述研究的哈佛大學（心理系教授）丹尼爾．夏克特說：「這項研究對特定種類的回溯性記憶增強提供有力的證據。」

He and others cautioned that the details of the process were unclear. No one knows which past memories an emotional experience flags, how far back in time it reaches or, indeed, whether it also suppresses some details. Memories are not fixed when encoded, experts said, and can be weakened by later events, as well as strengthened.
他和一些其他人士警告，記憶適應過程的細節不詳。沒有人知道一段激動的經驗會招來哪一段回憶，能回到多久之前的過去，抑或，某些細節甚至在過程中確實受到了壓抑。專家說，記憶在編碼時並非固定的，可能因為後來的事件而減弱或增強。

The study, done at New York University, had several stages. In the first one, the 119 participants sat in front of a computer watching photographs scroll by, and categorized each one as a tool (hammer, saw, ladder) or an animal (horse, eagle). They saw 30 tools and 30 animals, in no order.
在紐約大學進行的這項研究，分成好幾個階段。在第一個階段，119名受試者坐在電腦螢幕前，注視一張張開展的照片，並且將每張照片歸類為一種工具（鐵鎚、鋸子）或一種動物（馬、鷹）。受試者看了30種工具和30種動物，彼此間並無順序。

Five minutes later, the men and women again sat in front of the computer, only this time with electrode wires attached to one wrist. The research team, led by Joseph Dunsmoor, a postdoctoral fellow, calibrated a shock level for each person that was uncomfortable. The participants then categorized a new set of 60 photographs, 30 tools and 30 animals, in random order. Half of the group received a shock most times they saw an animal, and half received one most times they saw a tool. The research team then gave the participants a surprise test, measuring how well the participants remembered all the photographs. The results varied depending on when people took the test.
五分鐘後，這些有男有女的受試者又坐在電腦前，但這次手腕接有電極線。博士後研究員約瑟夫．唐斯摩帶領的研究團隊，校準讓每個人不舒服的電擊強度。受試者然後給60張新的照片分類，仍為隨機出現的30種工具和30種動物。半數受試者大多在看到動物時遭受電擊，另一半的受試者大多在看到工具時被電擊。研究團隊然後舉行突擊測驗，評量受試者能記得幾張照片。結果因接受測驗的時間而異。

Those who took it right away remembered as many tools as they did animals; the shocks had no apparent effect. But those who took the test six hours or a day later recalled about 7 percent more items from the “shocked” category. For example, they remembered more tools if they had been zapped seeing tools.
馬上接受測驗的受試者，記得的工具數和動物數一樣多，表示電擊並無明顯效果。但是六小時或一天後才接受測驗的人，在「遭電擊」的類別記得的數量多7%。例如，如果他們看見工具時被電擊，記得的工具就比較多。

“The emotional experience of the shocks strengthened or preserved the memories of things that, at the time they were encoded, seemed mundane,” Dr. Dunsmoor said.
「電擊的情緒經驗在記憶收錄時，強化或保存了對看似無奇的事物的記憶，」唐斯摩博士說。

The fact that the retroactive strengthening took time to happen leaves the timing unclear.
回溯性記憶增強的發生需要時間，但發生的時機仍然不明。

Dr. Schacter said, “That’s the most surprising finding to me, that the enhancement depends on some consolidation process we don’t yet understand.”
夏克特博士說：「這是讓我最訝異的發現，增強作用取決於某些我們不甚了解的固化過程中。」

原文參照：
http://www.nytimes.com/2015/01/22/health/study-shows-brain-stores-seemingly-trivial-memories-just-in-case.html

2015-02-10聯合報/G5版/UNITED DAILY NEWS 張佑生譯 原文參見紐時週報十版下