心灵中的朝花夕拾

原文出处：

Oakley, Barbara; Rogowsky, Beth; Sejnowski, Terrence J.. Uncommon Sense Teaching: Practical Insights in Brain Science to Help Students Learn (pp. 23-24). Penguin Publishing Group. Kindle Edition.

导言：

摘录的段落简述了长期记忆对工作记忆的扩展作用。作者将工作记忆比作握球的章鱼，章鱼的触手数目（亦即工作记忆在特定时刻所能持有的信息单元的最大数目）是给定的，平均为4个，无法通过教育或训练来增加，但通过取用（retrieve）长期记忆中存储的背景知识，每一个触手握住的“球”或信息块（chunk）的尺寸可以变大，造成工作记忆容量增大的表象。所以教育对于工作记忆的帮助仍然在于传授和积累背景知识，使长期记忆中贮存更多可以被取用的重要信息块，如阅读中的拼写映射（orthographic mapping）对记忆单词的作用，又如植物分类学的背景知识对记忆具体物种的作用。对于工作记忆“触手”数相近的大多数人来说，是他们的长期记忆更多决定了特定领域的工作记忆容量以及信息汲取速度。段落中最令人印象深刻的是这样一个比喻：在任何时候，长期记忆都会像婚礼上不请自来的客人（wedding crasher）一样闯入对工作记忆的测试，使人很难单独测出工作记忆本身的容量。

对于教师来说，学生在特定学术领域的困难，如语言学习障碍，阅读障碍和数学障碍，仅仅归因于工作记忆的缺陷虽然可能在事实层面上是正确的，但对指导实践并没有太大的意义，了解长期记忆如何作用于工作记忆更有助于理解自己在如何帮助学生，以及为什么没有快速捷径。在特殊教育领域有一整套适应有工作记忆缺陷的学生的教学技术，比如使用笔记大纲填空而不是让学生独立做笔记，比如将信息分割成小块多步喂食，比如使用简洁清晰的教学语言和指令，比如将工作步骤书面化可以随时参阅等等。但对于大多数吸收信息吃力的学生来说，他们的困难很可能来自于对这一领域的陌生，亦即接触机会和学习经验的相对贫乏，没有可以借助的长期记忆。这时候将练习，重复和学习时间趣味化，帮助建立必要的背景知识，要比一味适应学生的“缺陷”更能抬高他们的学习天花板。心理学上有“马修效应”（matthew’s effect)一说，谓穷者更穷，富者更富。在这里，背景知识决定了接下来吸收信息的速度，低龄时的小差距会随着年龄增长快速扩大，这也是教师难以帮助学习困难学生追赶进度的重要原因。

But remember, long-term memory can ultimately become a part of working memory, especially with retrieval practice. This is good news. It means that if the person with a lesser-capacity working memory creates and strengthens neural links in long-term memory, those links can extend their working memory on that topic. Another way of saying this is that the more assistance working memory gets from the prior knowledge stored in long-term memory, the easier it is for students, especially students with less capacity in their working memory, to learn new material.

Background practice is critical in ways that can at first be difficult to grasp. For example, let’s take the sentence “The green penguin is eating an apple.” It would be easy for you to write each letter of the sentence down a minute later. Now let’s take another sentence: “Зеленый пингвинест яблоко.” Unless you’re a Russian speaker, it’s going to be pretty difficult for you to hold all the letters in mind and write them down a minute later, even though the Russian green penguin is similarly eating an apple. Our working memory capacity appears to be much greater, depending on whether our long-term memories have had English or Russian implanted. Your background training matters—a lot. It increases the size of the “balls” of information (sometimes referred to by neuroscientists as chunks) that your working memory can hold. So even though the number of arms on your attentional octopus can’t increase, more background training on that topic means you can hold more information in working memory. The balls of information your octopus can hold are bigger.

As researcher John Sweller, perhaps best known for his theories related to cognitive load, has pointed out, the intricate relationship between working memory and long-term memory is easily the most critical factor in human cognition. It goes a long way toward understanding how our mind works. But long-term memory is like a wedding crasher—it sneaks into any attempt to measure working memory. This is because the contents of long-term memory massively transform the capacity of working memory.

Sadly, there’s no good evidence from research that general working memory capacity can be increased through training—although something that looks like working memory increase occurs within specific areas of practice. (This relates to the idea that the attentional octopus can juggle larger balls of information with the same number of arms—if, that is, the information has been well-practiced to strongly secure it in long-term memory.) In other words, practice with geometry can increase a student’s apparent working memory capacity with geometry. Practice with a language—say, French—can increase apparent working memory capacity with French. Practice with the piano can increase apparent working memory capacity with piano, and so forth. Of course, no one wants to create and strengthen links via poorly designed “drill and kill” approaches. But as we shall see in chapter 6, drill is not all bad—in fact, when drill is done properly, the expression might better be put as “drill and skill.” Given additional time and well-designed practice, people with lesser-capacity working memories can become as good as those with larger-capacity working memories in their areas of expertise—or even better.

The transformative effect of education is not that it changes students’ working memory capacity. Education instead changes the amount of knowledge held in long-term memory. The more knowledge held in long-term memory, the easier it is to add more. (This is the expertise reversal effect, where the more knowledgeable students are about a topic, the less guidance they need. Too much guidance in these situations can impede learning.) With the right kind of information implanted in long-term memory, people can effortlessly process enormous amounts of information—even if their working memories aren’t that capacious. This is why building students’ prior knowledge in a given subject area is critical.