Mnemonics

What is a mnemonic?

A mnemonic (pronounced “nih-MON-ik”) is any technique that makes information easier to remember by tying it to something your memory handles better. Most researchers think mnemonics work by drawing on what memory already does well: forming mental images, organising material and linking new information to what you already know.^[1]

Some mnemonics serve a single fact, like an acronym for the Great Lakes. Others are reusable structures: a memory palace, once learned, can hold a new shopping list every week.^[1]

What are the main types of mnemonic devices?

The common types of mnemonics differ in what they turn information into: a word, a sentence, a rhyme, a few groups, an image or a place.

Chunking works because how much you can hold in mind at once depends on the number of chunks more than on their size.^[2] The keyword example comes from a classic study of the method.^[3]

The method of loci, better known as the memory palace, is the most famous of these. You memorise a route through a place you know well, leave a vivid image of each item at a stop along the way, and recall the list by walking the route in your mind. It has its own page: the memory palace.

Do mnemonics work?

Mnemonics work for the right material, mostly over short delays; the evidence that they help weeks later is thinner. The record differs by type:

• Keyword method. The best-studied. In a 1975 study, students learning 120 Russian words recalled 72% of the translations the day after their last session, against 46% for students who studied their own way.^[3] But when students learning French words were tested only once, a week later, keyword users had forgotten faster and did no better than students who had simply repeated the words.^[4][1] A 2013 review of study techniques rated the keyword mnemonic “low utility”: hard to use in some contexts, and helpful for few kinds of material and mainly over short delays.^[5]
• Acronyms and acrostics. These are the mnemonics students use most, yet studies disagree on whether they improve recall. A first letter is a weak cue unless you already know the material well.^[1]
• Memory palace and peg system. Both reliably help with lists of concrete objects, especially in a set order. They may also last longer than keywords, because the places and pegs are well learned and stay the same.^[1]

When are mnemonics worth using?

Mnemonics are worth using for arbitrary information, where there is no logic to understand: vocabulary, names, lists and sequences. Nothing in the sound of zvonok suggests a bell, so the link has to be invented.

They are not a substitute for understanding. Mnemonics were designed to help recall, and evidence that they help reasoning or transfer to new problems is limited.^[1] They work best as a cue for knowledge you already have: OCEAN can help you list the Big Five personality traits on an exam, but only if you have learned what openness or conscientiousness means.^[1] They also cost time. Building a memory palace or peg list pays off only if you reuse it.^[1]

How do you make a mnemonic that works?

A good mnemonic is concrete, vivid and leads back to exactly one answer. A few rules help:

• Make the images interact. The bells hang from the oak; they do not stand next to it. The keyword method asks for an image of the keyword and the meaning together.^[3]
• Make your own when you have time. Mnemonics you create yourself are probably better once you have some practice and enough time, while ready-made ones help beginners and learners under time pressure.^[1]
• Keep it unambiguous. If “dentist” is your keyword for the French la dent, you may later wonder whether it meant tooth, mouth or gums.^[1]
• Save them for what will not stick. Most facts do not need a mnemonic. Keep them for the items you keep forgetting.

How do mnemonics fit with spaced repetition?

A mnemonic helps you learn an item; spaced repetition helps you keep it. The mnemonic makes the first link easier to form, but that link still fades along the forgetting curve unless you retrieve it again, at growing intervals.

The two seem to add up. One explanation for the mixed keyword results is that the studies where keywords lasted had usually also tested students right after learning, and that test is itself retrieval practice.^[1] In a 2007 study, combining keywords with retrieval practice led to better recall of foreign words a week later than either technique alone, although only when translating into English, not out of it.^[6]

In a flashcard app such as Anki, put the mnemonic on the back of the card, next to the answer. You see it when you check, and it does not become a hint before you try to recall. See the spacing effect.