韩国十大恐怖片:人脑发育缓慢——或许是人类成功的奥秘

Human brains are slow to develop--a secret, perhaps, of our success

人脑发育缓慢——或许是人类成功的奥秘

By Melody Dye  | February 9, 2010 | 

At every stage of early development, human babies lag behind infants from other species.  A kitten can amble across a room within moments of birth and catch its first mouse within weeks, while its wide-eyed human counterpart takes months to make her first step, and years to learn even simple tasks, such as how to tie a shoelace or skip a rope, let alone prepare a three-course meal. Yet, in the cognitive race, human babies turn out to be much like the tortoise in Aesop’s fable: emerging triumphant after a slow and steady climb to the finish. As adults, we drive fancy sports cars, leap nimbly across football fields and ballet stages, write lengthy dissertations on every conceivable subject, and launch rockets into space.  We have a mastery over our selves and our environments that is peculiar to our species.

在早期发育的每个阶段，在发育速度上，人类的婴儿都被其他动物的幼崽甩在了后面。小猫崽降生不久就能横穿房间漫步，几周内就能抓到第一只老鼠；而它们天真的对手——人类的婴儿却要花几个月才能迈出第一步，几年才能学会简单的任务，诸如如何系鞋带、跳绳或者独自准备有三道菜的一餐饭。在认知能力的竞赛中，人类更是慢得像伊索寓言里的乌龟：经历缓慢而沉稳的爬行才到达终点。作为成年人，我们能操纵设计精妙的跑车；无论在足球场上还是在芭蕾舞台上，我们都能敏捷矫健地跳跃自如；在任何能想像到的领域，我们都能写出长篇大论的论文；我们甚至还能把火箭送上太空。

Yet, this victory seems puzzling. In the fable, the tortoise wins the race because the hare takes a nap. But, if anything, human infants nap even more than kittens! And unlike the noble tortoise, babies are helpless, and more to the point, hopeless. They could not learn the basic skills necessary to their independent survival even if they tried. How do human babies manage to turn things around in the end?

是的，胜利来得很蹊跷。在寓言里，乌龟获胜是因为兔子打了盹。如果是因为这个的话，那人类婴儿打得盹可比小猫崽还要多！而且，与高贵的乌龟不同，人类的婴儿很无能，更糟的是，他们简直不可救药。无论怎么尝试，他们也无法独自学会生存所需的基本技能。那么人类的婴儿最终是如何扭转局势的呢？

In a recent article in Current Directions in Psychological Science, Sharon Thompson-Schill, Michael Ramscar and Evangelia Chrysikou make the case that this very helplessness is what allows human babies to advance far beyond other animals. They propose that our delayed cortical development is precisely what enables us to acquire the cultural building blocks, such as language, that make up the foundations of human achievement. Indeed, the trio makes clear that our early vulnerability is an evolutionary “engineering trade-off,” much like the human larynx—which, while it facilitates the intricate productions of human speech, is actually quite a precarious adaptation for anyone trying to swallow safely. In the same way, they suggest, our ability to learn language comes at the price of an extended period of cognitive immaturity. 

在《心理学》杂志的“潮流方向”栏目中，由Sharon Thompson-Schill、 Michael Ramscar 和 Evangelia Chrysikou三人发表了一篇文章。文中阐述了正是由于人类婴儿的无能，使得他们与其他动物相比占了巨大优势。文章认为，人类延后的脑皮质发育恰恰使得人类获得了构筑文化的基石，例如语言，构成了人类成功的基础。文章明确了人类早期的弱点是进化的“工程协议”，就像人的喉咙一样，当它能够发出复杂的人类语言时，同时也使安全的吞咽有了相当的不确定性。同样地，文章还指出，人类学习语言的能力是以长时期的认知不成熟为代价的。

This claim hinges on a peculiar and unique feature of our cognitive architecture: the stunningly slow development of the prefrontal cortex (PFC). While other animals’ brain regions development in synchrony, in humans, the development of the PFC lags far behind that of other areas. The PFC is the swath of gray matter that makes up the anterior frontal lobes, and functionally, it appears to be heavily implicated in a wide-range of sophisticated planning and attention driven behaviors. Indeed, it is often referred to as the “control” center of the brain. One of its main functions appears to be that of selectively filtering information from the senses, allowing us to attend to specific actions, goals, or tasks. For this reason, “cognitive control” tasks are thought to be one of the best assessors of PFC function and maturity, and they are tests that young children reliably, and ignominiously, fail.

这一观点是基于人类奇特而独一无二的认知结构——发育惊人缓慢的前额皮质（PFC）。其他动物的大脑区域发育是同步的，而人类的PFC发育远远慢于大脑其他区域。PFC是组成额叶前部的一排灰质，在功能上，它与广泛的复杂规划和注意力导向行为密切相关。的确，它通常被认为是大脑的“控制”中心。它的一个主要功能是有选择性地过滤外部信息，使得我们专注于特定的行为、目标或任务。因此，能否“有认知地操控”任务被认为是评价PFC的功能和成熟度的最佳标准，而确定和遗憾的是，这项标准小孩子显然无法通过。

The Stroop task serves as a simple assessor of PFC function in adults. The task involves naming the ink color of a contrasting color word: for example, you might see the word “red” written in green ink, in which case you have to say “green.” The task is tricky since it demands that we override a well learned response (saying “red” in response to seeing the word red) with a new response specific to the task (naming the conflicting ink color). Tricky or not, healthy adults can successfully complete the task with only minor hesitation.

对成年人来说，PFC功能最简单的评价标准是斯特鲁法（Stroop task）。测试包括说出墨水的颜色，而这墨水写出的字代表着另一种颜色。比如，你可能会看到用绿墨水写的“红”字，而你应该说出的是“绿”。这个测试很棘手，因为它要求我们摒弃常规反应（说出“红”是我们看到红这个字的常规反应），而去做出一个针对该测试的新的反应（说出墨水颜色）。无论棘手与否，健康成年人都能成功通过，只需要稍稍迟疑。

Children, with their immature PFC’s, are a different story. Typically, the younger children are, the worse they are at solving Stroop-like tasks, and under the age of four, they outright fail them. While young children are sensitive, apt learners, and often appear to fully understand what is being asked of them, they are unable to mediate the conflicting demands present in these sorts of tasks, and thus fail them, time and time again. Three-year olds simply cannot direct how they attend to or respond to the world.

由于PFC不成熟，对于该测试，儿童的情况就不一样了。一般地，儿童年龄越小，在斯特鲁测试中的表现越糟。4岁以下的儿童则完全无法通过测试。尽管小孩子敏感、乐于学习并常常看似完全明白你的问话，他们却无法解决在这类测试中所展现的矛盾的需求，因此一次又一次地测试失败。3岁大的儿童一般无法对自身目的和对外界的反应做出明确指向。