大脑会删除2岁前的记忆？网友：那些糗事，忘记也罢……

2023-08-27 07:08

逢年过节走亲访友，长辈们总会争先爆料你的糗事，比如滑着滑板撞树上了，或是哪天闹脾气不肯让他们抱，但你努力搜索大脑却还是一片茫然：什么时候发生过啊？我怎么一点印象都没有了？‍‍‍‍

近日，#大脑为什么删除2岁前的记忆#登上热搜，引发了网友们的热烈讨论。有的网友觉得很庆幸，童年的糗事，忘记也罢。

网友评论截图

调查显示，大部分人对自己两岁之前的事没有记忆，或者印象非常模糊，而少部分“天选之子”还能隐约记得一些。这究竟是为什么呢？丢失的记忆还能被找回吗？

原来是童年失忆症

现代医学给这种现象取了个名字，叫做“童年失忆症（Childhood Amnesia）”，指的是成年人无法回忆起自己2岁或者4岁之前的情景记忆（episodic memories）；也指在2-6岁之间，童年早期记忆的碎片化。

Childhood amnesia, also called infantile amnesia, is the inability of adults to retrieve episodic memories (memories of situations or events) before the age of two to four years. It may also refer to the scarcity or fragmentation of memories recollected from early childhood, particularly occurring between the ages of 2 and 6.

右脑半球的海马体示意图图源：Pixabay

童年失忆症是大脑发育的正常现象，并不能严格意义上称之为疾病。人的记忆需要大脑颞叶中海马体（hippocampus）的协助，而婴儿刚出生时，海马体尚未发育完全，会慢慢随着婴儿长大逐步发育，在四岁左右渐趋成熟。因此幼儿的早期记忆相对脆弱，没有被反复讲述和强化的记忆会随着时间的推移而消失。

Childhood amnesia is a normal part of brain development. Episodic memories involve the hippocampus, a part of the brain found in the temporal lobe, which is not fully developed at birth. The hippocampus should be ready at about the age of 4. Memories that are not repeatedly re-told and strengthened become lost over time.

沉思的孩子图源：视觉中国

长期以来，科学家们认为童年失忆症是因为幼儿的大脑根本无法形成对特定事件的持久记忆。更多的研究提供了证据，表明在童年的某个时候，人们失去了对早期记忆的访问。

For a long time, scientists thought childhood amnesia occurred because the brains of young children simply couldn't form lasting memories of specific events. More studies provided evidence that at some point in childhood, people lose access to their early memories.

研究者们做了一个实验，询问年长一些的孩子们是否能回忆起3岁时候的事。实验结果显示，7岁的孩子仍然可以回忆起自己3岁时期60%以上的事件，而8、9岁的孩子只能回忆起不到40%。

And they found that children as old as 7 could still recall more than 60 percent of those early events, while children who were 8 or 9 recalled less than 40 percent.

图源：杨越绘画

但并不是所有童年记忆都会被删除。平均而言，童年失忆症的覆盖范围在4.7年左右。当儿童到了5、6岁之后，他们的自传记忆（autobiographical memory）逐渐稳定，几乎与成年人相当。自此，童年记忆就不会再轻易被删除了。

On average, this fragmented period wanes off at around 4.7 years. Around 5-6 years of age in particular is thought to be when autobiographical memory seems to stabilize and be on par with adults.

童年记忆也会做筛选

纽芬兰纪念大学（Memorial University of Newfoundland）的学者卡罗尔·彼得森（Carole Peterson）表示，一些童年记忆更容易被记住。这些记忆的共同特点是事件发生时必然感情充沛，或是激动人心，或是声泪俱下。

快乐的孩子图源：视觉中国

Some early memories are more likely than others to survive childhood amnesia, says Carole Peterson at Memorial University of Newfoundland. One example, she says, is a memory that carries a lot of emotion.

在她的研究中，有一个男孩长大后仍能清晰地回忆起他18个月大时的一件事，那天他的母亲生下了另一个婴儿。男孩表示，他仍然记得当时自己有多么紧张难过，如何趴在厨房地板上哭泣，就连泪滴溅落在油毯上的形状都历历在目。

A child in one of Peterson's studies recalled an event from when he was just 18 months old. It was the day his mother went to the hospital to give birth to a sibling. "He remembers crying on the floor of the kitchen, and he remembers how upset he was," Peterson says. "And he can remember the pattern of his teardrops on the linoleum."

很多网友也评论依然保留小时候的记忆。

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网友评论截图

满载着情感的记忆，或是大型的生理、心理创伤，比如猛跌一跤头破血流的剧烈疼痛、父母争执满地狼藉的恐慌、生日那天收到的满溢的爱与惊喜……这样的事件会在幼儿心中产生不可磨灭的印象，冲破童年失忆症的普遍阻碍，在记忆里一遍一遍地回放，即便成年后都无法忘记。

用关爱抵抗遗忘

既然婴儿记不住早期记忆，是不是表示2岁前发生任何事情对他们都没有影响呢？答案是否定的。

网友评论截图

父母在孩子早期记忆形成与人格培养上起着不可或缺的作用。在充满爱与温馨的环境里长大的儿童会更健康顺利地成长，记得更多4岁前的事件。

关于情感创伤和童年失忆症的研究表明，童年的痛苦经历会破坏人的记忆，并损害记忆系统的核心部分，如海马体和杏仁核（amygdala）。

Examining the effects of emotional trauma and childhood amnesia shows that stressful experiences do in fact disrupt memory and can damage central parts of the memory system such as the hippocampus and amygdala.

图源：视觉中国

在童年受到虐待、产生创伤的成年人形成的最早记忆大约比健康成长的人群晚2-3年。此外，与没有受过创伤的人相比，他们在视觉、图像和面部记忆的存储和检索方面也有较大的缺陷。

Adults who were abused or traumatized in childhood form their earliest memories about 2–3 years after the general population. In addition, they demonstrate considerable problems with visual, pictorial, and facial memory storage and retrieval compared to non-traumatized individuals.

图源：杨越绘画

父母需要和年幼的孩子一起创造温馨的回忆。即使由于童年失忆症，他们长大后也许并不记得，但建立起健康稳定的亲情连接，帮助幼小的孩子了解世界，对孩子心理和大脑的成长至关重要。比如带着孩子来一趟愉快的动物园之旅，也许他们长大会忘记具体做了什么，但他们会对动物园以及动物感到熟悉和安全。

It is still really important to do things with your young children even though they won't remember them when they are older. Sharing experiences is important for bonding and helps your child learn about the world around them.