Anki 是一款可以让记忆变得简单的软件。它比传统学习方法更有效率，你可以大大减少你花在学习上的时间，而增加你学到的东西。

Anki is a program which makes remembering things easy. Because it is a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.

任何想要在日常生活中记忆东西的人都能受益于 Anki。Anki 采用的是（content-agnostic）模式，并且支持图像、音频、视频、以及科学标记语言（通过 LaTeX 实现），因而具有无限的可能性。例如：

Anyone who needs to remember things in their daily life can benefit from Anki. Since it is content-agnostic and supports images, audio, videos and scientific markup (via LaTeX), the possibilities are endless. For example:

• 学习一门语言

  learning a language

• 备考医学和法律

  studying for medical and law exams

• 记忆人名和长相

  memorizing people’s names and faces

• 复习地理知识

  brushing up on geography

• 记长诗

  mastering long poems

• 甚至练习吉他和弦

  even practising guitar chords!

Anki 包含两个简单的概念：主动回忆测试和间隔重复。尽管许多年来，有很多科学文献提及这两个概念，但是大多数学习者对其一无所知。了解这两个概念如何起作用能让你成为更有效率的学习者。

There are two simple concepts behind Anki: active recall testing and spaced repetition. They are not known to most learners, despite having been written about in the scientific literature for many years. Understanding how they work will make you a more effective learner.

主动回忆测试

Active Recall Testing

主动回忆测试(Active Recall Testing)意思是使用者被提问一个问题并且努力回答这个问题。这与被动学习形成了鲜明对比，在被动学习中，我们阅读、观看或听一些东西，而不停下来思考是否知道答案。研究表明，主动回忆测试在建立强大记忆方面比被动学习有效得多。有两个原因：

Active recall testing means being asked a question and trying to remember the answer. This is in contrast to passive study, where we read, watch, or listen to something without pausing to consider if we know the answer. Research has shown that active recall testing is far more effective at building strong memories than passive study. There are two reasons for this:

• 回忆某件事会增强对该事的记忆，增加我们记住它的几率。

  The act of recalling something strengthens the memory, increasing the chances we’ll be able to remember it again.

• 当我们答不上问题时，我们需要回到材料当中，复习或者重新学习材料。

  When we're unable to answer a question, it tells us we need to return to the material to review or relearn it.

你可能在上学的时候遇到过主动回忆测试，甚至都没有意识到。当优秀的老师在读完一篇文章后给你一系列需要回答的问题，或者让你每周进行进度检查测试时，他们这样做并不是为了看看你是否理解材料。通过测试你，增加了你将来记住这些材料的几率。

You have probably encountered active recall testing in your school years without even realizing it. When good teachers give you a series of questions to answer after reading an article, or make you take weekly progress-check tests, they are not doing it simply to see if you understood the material or not. By testing you, they are increasing the chances you will be able to remember the material in the future.

将主动回忆测试融入你自己学习中的一个好方法是使用闪卡。用传统的纸质卡片时，你在卡片的一面写一个问题，在另一面写答案。只有在想起问题的答案之后，你才能翻转卡片。你的学习效率会比采用被动观察的方法更高。

A good way to integrate active recall testing into your own studies is to use flashcards. With traditional paper flashcards, you write a question on one side of a card, and the answer on the other side. By not turning the card over until you've thought about the answer, you can learn things more effectively than passive observation allows.

要么使用，要么失去

Use It or Lose It

我们的大脑是高效运转的机器，它们会迅速丢弃看似无用的信息。你可能不记得两周前的星期一的晚餐吃了什么，因为这些信息通常没有用处。然而，如果你那天去了一家很棒的餐厅，并在过去的两周里告诉人们它有多棒，你可能仍然记得非常详细。

Our brains are efficient machines, and they rapidly discard information that doesn't seem useful. Chances are that you don't remember what you had for dinner on Monday two weeks ago, because this information is not usually useful. If you went to a fantastic restaurant that day and spent the last two weeks telling people about how great it was, however, you're likely to still remember in vivid detail.

大脑的“要么使用，要么失去”原则适用于我们所学的一切。如果你花一个下午的时间背一些科学术语，然后两周都不想这些材料，你可能已经忘记了大部分。事实上，研究表明，我们在 48 小时内忘记了大约 75% 的材料。当你需要学习很多信息时，这看起来很令人沮丧！

The brain's "use it or lose it" policy applies to everything we learn. If you spend an afternoon memorizing some science terms, and then don't think about that material for two weeks, you'll probably have forgotten most of it. In fact, studies show we forget about 75% of material learnt within a 48 hour period. This can seem pretty depressing when you need to learn a lot of information!

不过，解决方法很简单：复习。通过复习近期所学信息，我们可以大大减少遗忘量。

The solution is simple, however: review. By reviewing newly-learnt information, we can greatly reduce forgetting

唯一的问题是，传统上，复习并不是很实际。如果你使用的是纸质卡片，如果你只有 30 张卡片要复习，那么很容易浏览所有的卡片。但随着数量增长到 300 或 3000 张，很快就会变得难以操作。

The only problem is that traditionally, reviewing has not been very practical. If you are using paper flashcards, it's easy to flick through all of them if you only have 30 of them to review, but as the number grows to 300 or 3000, it quickly becomes unwieldy.

间隔重复

Spaced Repetition

间隔效应是由德国心理学家赫尔曼·埃宾豪斯在 1885 年提出的。他观察到，如果我们随着时间的推移分散复习，而不是在一节课上学习多次，我们往往会更有效地记住事情。自 20 世纪 30 年代以来，人们提出了许多利用间隔效应来改善学习的建议，即所谓的间隔重复(Spaced Repetition)。

The spacing effect was reported by a German psychologist Hermann Ebbinghaus in 1885. He observed that we tend to remember things more effectively, if we spread reviews out over time, instead of studying multiple times in one session. Since the 1930s, there have been a number of proposals for utilizing the spacing effect to improve learning, in what has come to be called spaced repetition.

一个例子是在 1972 年，一位名为 Sebastian Leitner 的德国科学家推广了使用纸质卡片的间隔重复法。通过将卡片分别放入多个盒子中，并将复习成功和复习失败的卡片各自放入一个不同的盒子中，就可以对于卡片的熟悉程度有个大致的估计，以及能够知道什么时候需要再次复习卡片。这相比于将卡片放入单个盒子的方法而言有了很大的改善，并且该方法已广泛应用于计算机化抽认卡软件。然而该方法相对而言不是很完善，因为它无法为你提供何时需要再复习某事的确切日期，并且不能很好地适应学习难度不同的材料。

One example was in 1972, when a German scientist called Sebastian Leitner popularized a method of spaced repetition with paper flashcards. By separating the paper cards into a series of boxes, and moving the cards to a different box on each successful or unsuccessful review, it was possible to see at a glance a rough estimate of how well a card was known and when it should be reviewed again. This was a great improvement over a single box of cards, and it has been widely adopted by computerized flashcard software. It is a rather rough approach however, as it cannot give you an exact date on which you should review something again, and it does not cope very well with material of varying difficulty.

过去 30 年里，最长远的进展来自于 SuperMemo 的作者，SuperMemo 是一款商业抽认卡程序，采用了间隔重复法。SuperMemo 首创了一个系统，能够了解何时复习学习材料最为合适，并且会根据用户的表现对系统进行优化。

The biggest developments in the last 30 years have come from the authors of SuperMemo, a commercial flashcard program that implements spaced repetition. SuperMemo pioneered the concept of a system that keeps track of the ideal time to review material and optimizes itself based on the performance of the user.

在 SuperMemo 的间隔重复系统中，每次你回答一个问题，不管是完全忘记答案、答案略有错误、能费力地想起答案、还是能轻易想起答案等等，你都是在告知程序你对答案的记忆牢固程度。程序会用该反馈来决定再次向你展示问题的最佳时机。每次你成功回想起答案，对其的记忆都会随之加深，因此复习的时间间隔会越来越长，例如你可能在初次看见某个问题之后，要在 3 天、15 天、45 天后才会再次看到该问题，以此类推。

In SuperMemo's spaced repetition system, every time you answer a question, you tell the program how well you were able to remember it — whether you forgot completely, made a small mistake, remembered with trouble, remembered easily, etc. The program uses this feedback to decide the optimal time to show you the question again. Since a memory gets stronger each time you successfully recall it, the time between reviews gets bigger and bigger — so you may see a question for the first time, then 3 days later, 15 days later, 45 days later, and so on.

这是学习方法的重大变革，意味着可以用最少的精力学会并记住学习材料。SuperMemo 的口号对其进行了概括：使用间隔重复法，你就不会再忘记。

This was a revolution in learning, as it meant material could be learnt and retained with the absolute minimum amount of effort necessary. SuperMemo's slogan sums it up: with spaced repetition, you can: "forget about forgetting".

为何要选择 Anki？

Why Anki?

虽然 SuperMemo 在该领域的影响巨大，这不可否认，但它也存在问题。人们经常批评 SuperMemo 的 Bug 很多，导航设计很差，且只能在 Windows 系统上使用。它是专有软件，意味着终端用户不能进行拓展或获取原始数据。尽管非常老的版本是免费的，但这些版本对于现在的用法来说相当有限。

While there is no denying the huge impact SuperMemo has had on the field, it is not without its problems. The program is often criticized for being buggy and difficult to navigate. It only runs on Windows computers. It is proprietary software, meaning that end-users cannot extend it or access the raw data. And while very old versions have been made available for free, they are quite limited for modern use.

而 Anki 解决了这些问题。Anki 拥有免费的客户端，可以在很多平台上使用，因此囊中羞涩的学生和教师们也可使用。Anki 也是一款开源软件，有很多终端用户所提供的插件。Anki 还是一款跨平台的软件，可以在 Windows、Mac 系统、Linux/FreeBSD 以及部分移动设备运行，并且 Anki 的使用难度远比 SuperMemo 低。

Anki addresses these issues. There are free clients for Anki available on many platforms, so struggling students and teachers with budgetary constraints are not left out. Anki is open source, with an already flourishing library of add-ons contributed by end-users. It is multi-platform, running on Windows, macOS, Linux/FreeBSD, and some mobile devices. And it is considerably easier to use than SuperMemo.

Anki 的间隔重复系统基于 SuperMemo 名为 SM-2 的旧版算法。

Anki's spaced repetition system is based on an older version of the SuperMemo algorithm called SM-2.