好像遗忘一直是个负面词。
背单词时候，你肯定不喜欢遗忘。
生活里面忘了的那些密码，钥匙，手机…
母语里面的“忘恩负义”等的表达。
貌似都在传递遗忘的弊端。
相反，记忆是个褒义词。
我们夸一个人过目不忘，掌握信息很快。
那就先从记忆说起吧。
纽约时报9月的时候有一篇文章，标题是Scientists Identify Neurons That Help the Brain Forget. 文章开头部分给我们讲了一个俄国人的故事。
这人有个特点，从不遗忘东西。
“… who later became known as subject S., by spouting long strings of numbers and words, foreign poems and scientific formulas, all of which S. recited back without fail. Decades later, S. still remembered the lists of numbers perfectly whenever Dr. Luria retested him….”
但这个记忆能力也给他带来了一定的困扰。
一个明显的问题是，人每天处理的信息太多，而如果所有信息大脑都收入的话，容易信息过载。（据说抑郁症比较重要的一个源头就是信息太多了，难以释怀）
所以遗忘在一定程度上是我们大脑主动去掉冗余信息的过程。
遗忘就是为了更好的记忆。
就像前面提到的，我们的记住太多东西对于我们人脑来说是有弊端的。
所以当我们要记住一些新的东西的时候，旧的就必须要让位。当然一般大脑会让出那些不那么重要的信息。只是大脑的判断和你的需求之间可能有时候会有落差。比如说你会觉得昨天记住的单词挺重要的，但是当你今天开始记忆新的单词的时候，好像有部分的昨天的单词被大脑让位出去了。
但是到底是你的大脑糊涂了，还是你糊涂了？ 很难说。
科学上来说，遗忘不是信息完全丢失了，只是这个信息去了一个不是那么容易被找到的地方（就是想起来没那么快）。
想一想记住一个新的密码的时候，老的是不是慢慢遗忘了（但是你努力想想，是不是也会能慢慢想起来）。
而过强的记忆能力，对于我们这位俄国人还有一个问题
“He had a hard time understanding abstract concepts or figurative language, and he was terrible at recognizing faces because he had memorized them at an exact point in time, with specific facial expressions and features. ”
这让科学家觉得遗忘对于人类的抽象创新能力尤为重要（ forgetting is required for the mental flexibility inherent in creative thinking and imagination.）
所以遗忘和记忆这对看着相反的机制，在人脑信息处理的时候，其实是相辅相成，同等重要的。
你所掌握，所经历的不同的知识不会简单的促进你的创新能力，是你忘掉的那部分知识，让你找到了新的方法，新的思路。
这也符合研究人员对于人脑的结构分析：人脑的记忆和遗忘的部分是紧密相连的（ the regions and mechanisms in the brain that are involved in memory formation are also connected to memory removal…)
我们记住一些过往，积累一些经验，为的是未来遇到类似的情况的时候，知道如何面对。
但是我们去忘记一些过往，又何尝不是让自己能更好的面对未来呢。
下面一篇文章，讲的就是一群科学家对于遗忘的研究。
原标题：Can We Get Better at Forgetting?
原作者：Benedict Carey
原刊于：New York Times
Whatever its other properties, memory is a reliable troublemaker, especially when navigating its stockpile of embarrassments and moral stumbles. Ten minutes into an important job interview and here come screenshots from a past disaster: the spilled latte, the painful attempt at humor. Two dates into a warming relationship and up come flashbacks of an earlier, abusive partner.
The bad timing is one thing. But why can’t those events be somehow submerged amid the brain’s many other dimming bad memories?
Emotions play a role. Scenes, sounds and sensations leave a deeper neural trace if they stir a strong emotional response; this helps you avoid those same experiences in the future. Memory is protective, holding on to red flags so they can be waved at you later, to guide your future behavior.
But forgetting is protective too. Most people find a way to bury, or at least reshape, the vast majority of their worst moments. Could that process be harnessed or somehow optimized?
Perhaps. In the past decade or so, brain scientists have begun to piece together how memory degrades and forgetting happens. A new study, published this month in the Journal of Neuroscience, suggests that some things can be intentionally relegated to oblivion, although the method for doing so is slightly counterintuitive.
For the longest time, forgetting was seen as a passive process of decay and the enemy of learning. But as it turns out, forgetting is a dynamic ability, crucial to memory retrieval, mental stability and maintaining one’s sense of identity.
That’s because remembering is a dynamic process. At a biochemical level, memories are not pulled from the shelf like stored videos but pieced together — reconstructed — by the brain.
“When we recall something, the act of recalling activates a biochemical process that can solidify and reorganize the memory that is stored,” said Andre Fenton, a neuroscientist at New York University.
This process can improve memory accuracy in the long term. But activating a memory also makes it temporarily fragile and vulnerable to change. This is where intentional forgetting comes in. It’s less about erasing than editing: incrementally revising, refocusing and potentially dimming the central incident of the memory.
To intentionally forget is to remember differently, on purpose. Importantly, for scientists and therapists, intentional forgetting also may be an ability that can be practiced and deliberately strengthened.
In the new study, a team led by Tracy Wang, a postdoctoral psychology fellow at the University of Texas at Austin, had 24 participants sit in a brain-imaging machine while they conducted a memory test. Dr. Wang’s co-authors were Jarrod Lewis-Peacock of the University of Texas and Katerina Placek of the University of Pennsylvania.
In the experiment, each subject studied a series of some 200 images, a mix of faces and scenes, and identified the faces as male or female, and the scenes as indoor or outdoor. Each image appeared for a few seconds, then disappeared, at which point the participant was asked to either remember or forget it; after a few seconds delay, the next image appeared. The brain scanner focused on activity in the ventral temporal cortex and the sensory cortex, regions that are especially active when a person focuses mental attention on simple images such as these.
After the participants finished, they were given a short rest and then a test. They looked at a series of images — ones they’d seen earlier and ones they hadn’t — and rated how confident they were at having seen each one. They scored well: they recalled 50 to 60 percent of the images they’d been instructed to remember, and successfully had forgotten about 40 percent of the images they tried to erase from memory.
The payoff came with the imaging results. When a subject’s brain activity — a measure of internal mental attention — was especially high or especially low, it typically corresponded to a failed attempt to forget an image.
A concentrated effort to forget an unwanted memory did not help dim it, nor did mentally looking the other way. Rather, there seemed to be a sweet spot — neither too little mental attention, nor too much — that allowed a memory to come to mind and then fade, at least partially, of its own accord. You have to remember, just a little, to forget.
“This suggests a new route to successful forgetting,” the authors concluded. “To forget a memory, its mental representation should be enhanced to trigger memory weakening.”
“When people were successful at doing this, there was a significant drop in their recognition confidence of images,” said Dr. Lewis-Peacock. “Whether a person’s intent is to weaken memories as a part of therapy, or to change them or link them to other things as a part of daily living, this finding speaks directly to that.”
Lili Sahakyan, an associate professor of psychology at the University of Illinois, who was not involved in the research, said: “This idea that memories have to be strengthened before they can be weakened is surprising in that it’s not how we presume memory works. But it’s a very solid finding, and we are following up on it.”
The insight joins an accumulating body of evidence casting doubt on a purely linear model of forgetting, which contends that less mental attention means less remembering. That model appears to hold for some kinds of memories; deliberate ignoring is central to the forgetting strategy known as suppression.
Other strategies are not strictly linear, in that they require some engagement with the memory. One is substitution: deliberately linking an unwanted memory to other thoughts, which help alter the unwanted content when it is later retrieved. For instance, a humiliating memory could be diminished by focusing less on the feeling of shame and more on the friends who provided subsequent support.
Scientists have not yet worked out which strategies are best suited to particular kinds of unwanted memories. But any clearer understanding would be a gift to therapists working with people with disabling memories of trauma, shame or neglect. Such memories don’t fade; they remain, either as vivid recollections or as subconscious or partially conscious sources of dread and despair. A therapist’s task is to guide the patient back through these memories in a way that blunts their sting, rather than reinforces them — a dicey and often painstaking process.
Dr. Lewis-Peacock said that his lab is looking at using real-time neurofeedback to nudge people who are trying to dim a memory into the mental state suggested by the new study: moderate engagement with the memory, not too much nor too little.
“We hope they can use that to say ‘Think more,’ or ‘Think less,’ to get themselves into that mental sweet spot,” he said.
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