原文: Jean Piaget's Four-Stage Theory: How Children Acquire Knowledge

He has the dubious claim to fame of having produced perhaps the most criticised psychological theory of all time. His experiments and theories about how children build up their knowledge of the world have faced endless challenges, many of them justified.

But because of his immense contribution and his grand vision it is fitting to round off this series on 10 crucial child psychology studies with the work of the famous Swiss developmental psychologist Jean Piaget.

To give you a flavour of why Piaget's research has faced so much criticism and also why psychologists often regard him with such awe, I'll describe one of the observations he made of his own three children, why his conclusions are probably wrong and the central insight at the heart of his four-stage theory.

When the duck is out of sight, it's out of mind

One of Piaget's many careful observations was made when one of his daughters, Jacqueline, then 7 months old, dropped a plastic duck on the quilt and it fell behind a fold so that she couldn't see it. Piaget noticed that despite the fact that Jacqueline could clearly see where the duck had dropped, and it was within her reach, she made no attempt to grab for it.

Fascinated by this, Piaget put the duck in her view again but, then, just as she was about to reach for it, he slowly and clearly hid it under the sheet. Again, she acted as though the duck had simply disappeared, making no attempt to search for it under the sheet.

This seemed strange behaviour to Piaget as Jacqueline was clearly interested in the duck while she could see it, but seemed to forget about it the instant it disappeared from view - out of sight and, apparently, out of mind.

What Piaget deduced from these observations, along with many experiments, was that children do not initially understand the idea that objects continue to exist even when out of sight. This concept, he thought, children had to work out by themselves by interacting with and experiencing the world.

It wasn't until around 9 or 10 months of age that Piaget noticed his children began to search for a hidden object.

Piaget's four-stage theory of development

While many parents play games with their children like this, what set Piaget apart was that he used these observations along with many experiments to develop a theory of how children acquire knowledge, a theory for which he is rightly best-remembered.

This theory is a four-stage ladder up which Piaget thought children climbed as they gathered knowledge about the world:

• Sensorimotor (birth to 18-24 months): infants are aware only of their sensations, fascinated by all the strange new experiences their bodies are having. They are like little scientists exploring the world by shouting at, listening to, banging and tasting everything.
• Pre-operational (18-24 months to 7 years): during this stage children can process images, words and concepts but they can't do anything with them, they can't yet operate on them. It's like they've acquired the tools of thought, but don't yet know how to use them. E.g. in maths they can't understand that 2 x 3 is the same as 3 x 2.
• Concrete operations (7 to 12 years): at this stage children gain the ability to manipulate symbols and objects, but only if they are concrete - abstract operations are still a challenge.
• Formal operations (12 and up): from here on children are able to think in abstract terms about the world. Now they can understand concepts such as the future, values and justice. From around this age children start thinking like adults.

It's for this grand theory of development that Piaget is much admired. Unfortunately, like many an ambitious theory, over time evidence was uncovered that contradicted aspects of this neat time-line.

For example Piaget's conclusions about his daughter Jacqueline's failure to reach for the duck were probably wrong. Subsequent studies have revealed infants as young as 3.5 months appear to understand object permanence. Psychologists nowadays might explain Jacqueline's behaviour as a failure of memory or an inability to grasp something that is out of view.

Einstein on Piaget: genius

Although findings such as these have chipped away at Piaget's theory, his work has continued to attract interest and stimulate research. From observations like hiding his daughter's duck to his grand four-stage theory, Piaget's central insight was that children think in a fundamentally different way from adults. They don't just have less knowledge, less experience or less processing power; the qualitative content of their thoughts is actually different.

Even though psychologists now question many of the details of Piaget's observations and theories, this central insight remains intact. And it's this central insight that Albert Einstein once described as "so simple that only a genius could have thought of it".


» This is part of a series on 10 crucial child psychology studies. Read more on the emergence of infant memory, self-concept, learning, attachment, social behaviour, theory of mind, object permanence, language and knowledge.

译文: 皮亚杰的四阶段发展理论：孩子怎样获取知识

      他一直不断地提出最有争议性的心理学理论，这些理论都是受到怀疑的。他关于儿童如何构造这个世界的知识的实验和理论已经面临了无穷无尽的挑战，其中很多已经被证实了。

      但是，由于他的伟大的贡献和重要的观点，著名的瑞士发展心理学家皮亚杰的研究也成了10大经典的儿童心理研究。

      为了让你明白为什么皮亚杰的研究遭到了这么多的批评但其他心理学家却依然对他非常尊敬，我将会描述一个他对他三个孩子中的一个的观察记录，还有为什么他的结论是错误的和在他的四阶段理论中的核心是什么。

      客体永久性

      皮亚杰有很多细致的观察，其中一个是在他的女儿杰奎琳身上发现的。在她7个月大的时候，她把一个塑料的鸭子丢在了被子上，它被被子的褶皱给挡住了，所以她看不到它。皮亚杰发现，虽然杰奎琳能清楚的看见鸭子被丢在哪里，而且她也能够得到它，但她却没有试着去把它拿回来。

      皮亚杰对这个现象产生了非常大的兴趣，他把鸭子再一次地放在她眼前，但当她正要来拿的时候，他慢慢地不留痕迹地把它又藏在了被褥里。再一次地，好像鸭子已经不见了一样，她没有尝试着在被褥中找它。

      皮亚杰对杰奎琳的这个行为感到非常奇怪。

      通过观察和不断的实验，皮亚杰推断，儿童在最初的时候并没有掌握客体永久性的概念。他猜测，儿童需要与这个世界相互作用并体验周围，才能够掌握这个概念。

      直到9个月或10个月时，皮亚杰才发现他的孩子开始寻找被藏起来的物体。

 

      皮亚杰的四阶段发展理论

      当很多家长像这样子和他们的孩子玩游戏时，让皮亚杰显得不同的时，他通过这样的观察和许多的实验来构建了一个关于孩子如何获取知识的理论体系，这个理论让他流传百世。 

      这个理论像一个有四个台阶的梯子，皮亚杰认为儿童在从世界中获取知识的过程中爬上了一个又一个的台阶。

      感觉运动时期（出生到18~24个月）：婴儿只对他们的感觉敏感，对他们身体感觉到的新的经验十分着迷。他们就像一个小科学家一样，通过声音、听觉、触觉和味觉来探索这个世界。

      前运算阶段（18~24个月到7岁）：在这个时期，儿童能够处理图像、文字和概念，但他们不会运用。他们已经获得了思考的工具，但仍不明白怎样来运用它们。比如，在数学中，他们不能明白2*3跟3*2一样。

      具体运算阶段（7岁到12岁）：在这个阶段，儿童获得了运用符号和图像的能力，但仅仅当他们是具体的情况下——抽象的操作仍然是一个挑战。

      形式运算阶段（12岁以上）：从这时开始，儿童能够以抽象的形式来思考这个世界。他们能够明白未来、价值和公正的概念。大概从这个年龄开始，儿童开始像成人一样思考了。         

      因为这个重要的发展理论，皮亚杰受到了广泛地称赞。不幸的是，像许多伟大的理论一样，随着时间的流逝，这个整齐的按时间发展的理论被一些证据证明了是自相矛盾的。

      例如，皮亚杰对他的女儿杰奎琳无法去拿回鸭子的结论或许是错误的。后来的研究表明，婴儿在3.5个月大时就已经能够理解客体永久性了。现在心理学家可能会对杰奎琳的行为做记忆的失败或者无法去够着看不见的东西。

      爱因斯坦对皮亚杰的评价：天才

      虽然皮亚杰的理论是有缺陷的，但他的研究仍然引起了很多人的兴趣，并促成了一些研究。除了客体永久性的概念，皮亚杰核心的观点是儿童与成人的思维方式上有根本上的不同。这种不同不是体现在他们拥有较少的知识、经验和操作能力；而是从性质上来说，他们思维的内容是完全不同的。

      虽然心理学家对皮亚杰的观察和理论的细节提出了许多疑问，但这个核心的观点仍然是牢固的。爱因斯坦曾经对这个观点做出这样的评价：“只有一个天才才能想出这样质朴的理论。”

      这是10个经典儿童心理学研究系列中的一个。你可以点击“儿童的记忆”、“自我概念”、“学习”、“情感”、“社会行为”、“精神分析”、“客体永久性”、“语言”和“知识”来阅读更多的内容。

      主办者：浏览http://www.parinc.com/获取有效的心理评估工具、主要的服务和快速的运输。