Mnemonic devices: 8 types with examples

A mnemonic device is a trick that makes something easier to remember by tying it to something your memory already handles well: a word, a sentence, a rhyme, a picture or a place. "My Very Educated Mother Just Served Us Noodles" is one. The first letter of each word gives you the planets in order from the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Mnemonic devices work best for things that have no meaning of their own to hold on to, like a list, an order, a name or a word in another language. This post covers eight types of mnemonic devices, with a classic example of each and one you can build yourself, a table of which type to use for what, and what research says about how well they work.

Types of mnemonic devices, with examples

1. Acronyms

An acronym takes the first letter of each item and makes a word you can say. HOMES gives you the Great Lakes: Huron, Ontario, Michigan, Erie and Superior. ROY G. BIV gives you the colors of the rainbow in order: red, orange, yellow, green, blue, indigo and violet. PEMDAS gives you the order of operations in math: parentheses, exponents, multiplication, division, addition and subtraction.

Acronyms only work when the first letters happen to make something pronounceable, or when the order of the items doesn't matter and you can shuffle them until they do. HOMES works because nobody needs the Great Lakes in a fixed order.

2. Acrostics

An acrostic is a sentence where each word starts with the same letter as an item on your list. It's the fix for lists whose first letters don't make a word. "Every Good Boy Does Fine" gives you the notes on the lines of the treble clef, E, G, B, D and F, and "Never Eat Soggy Waffles" gives you the points of a compass, clockwise from the top: north, east, south and west.

To make your own, write down the first letters and try words until the sentence makes a picture. Say you want the first five US presidents in order: Washington, Adams, Jefferson, Madison and Monroe. W, A, J, M, M becomes "Wise Ants Just Make Mounds". A silly or vivid sentence is easier to keep than a flat one, so pick the version you can see.

3. Rhymes and songs

A rhyme fixes the words in place, because a wrong word breaks the rhythm and you notice. "Thirty days hath September, April, June and November" has helped people count the days in each month for centuries, and "In fourteen hundred ninety-two, Columbus sailed the ocean blue" ties a date to an event. The alphabet song does the same with a tune: plenty of adults still hum it to find where a letter falls.

Rhymes take longer to write than acronyms. They're worth it for a short rule or a fact you'll need for years.

4. Chunking

Chunking means grouping many small items into a few bigger ones. A phone number like 5558675309 is ten digits, but 555-867-5309 is three chunks, and that's much easier to hold in your head. In 1956 the psychologist George Miller wrote that people can hold about seven items in short-term memory, and later work by Nelson Cowan put the number of chunks closer to four. Either way, grouping helps because each chunk counts as one item.

You can chunk anything with a lot of parts: a long password, an account number, or a list of 12 things to pack, split into clothes, papers and chargers.

5. The story method

The story method links the items on a list into a short story, so each one leads to the next. To remember milk, stamps, batteries, basil and a birthday card, you might picture a cow licking a stamp, which sticks to a battery, which rolls into a pot of basil, which grows a birthday card instead of leaves. The stranger the story, the better it sticks.

This method has one of the oldest pieces of evidence behind it. In a 1969 study at Stanford, Gordon Bower and Michael Clark asked one group of students to make up stories around lists of 10 nouns and another group to simply memorize them. When the students were later asked to recall all the lists, the story group remembered about seven times as many words.

6. The method of loci, or memory palace

The method of loci links each item to a place along a route you know well, like the rooms of your home. You picture an image of each item at its own stop, then walk the route in your mind to get the items back in order. It's the method memory champions use, and it's more than 2,000 years old.

I wrote a full guide to the memory palace, with the eight planets placed around an apartment as a worked example and the research on why it works.

7. The pegword method

The pegword method gives you a fixed set of "pegs" for the numbers one to ten, each a word that rhymes with its number: one is a bun, two is a shoe, three is a tree, four is a door, five is a hive. To remember a numbered list, you hang each item on its peg with a picture.

Say the third step of a recipe is "add the eggs". Picture eggs hanging from a tree, and "three" brings back the eggs. Once you've learned the pegs, you can reuse them for any list, and you can jump straight to item seven without going through the first six.

8. The keyword method for vocabulary

The keyword method helps you learn words in another language. You find an English word that sounds like the foreign word, then make a picture that joins it to the meaning. The Spanish word caballo (horse) starts like "cab", so you picture a horse driving a yellow cab. When you see caballo, the cab comes back, and the horse is sitting in it.

In a study at Stanford, Richard Atkinson and Michael Raugh taught 52 students Russian vocabulary. On the final test, the students who used the keyword method got 72% of the words right, against 46% for students who studied the same words in the usual way.

Which mnemonic device to use

How to make your own mnemonic

1. Decide exactly what you need to remember, and in what form. "The causes of World War I" is too vague. "The four long-term causes, in any order" is something you can build a mnemonic for, and many history students use MAIN: militarism, alliances, imperialism and nationalism.
2. Pick the type that fits, using the table above.
3. Make it concrete and a little strange. A horse driving a cab sticks better than a horse standing near one.
4. Test yourself right away: cover your notes, use the mnemonic to get the items back, and check what you missed.
5. Go back to it a day later and a week later. A mnemonic is a memory too, and it fades on the forgetting curve like anything else unless you use it.

Do mnemonic devices work?

For the right material, yes. Besides the story and keyword studies above, a 2017 study in Neuron found that people with no memory training who practiced the memory palace for 30 minutes a day over 40 days went from recalling about 26 of 72 words to about 62.

The limits matter as much. In 2013 a team led by John Dunlosky reviewed ten common study techniques and gave the keyword mnemonic a low utility rating. The review found it hard to use for many kinds of material, and its benefits often faded over longer periods. Mnemonic devices help you hold on to the shape of something, like a list, an order or a word. They don't help you understand why the planets are in that order or what the Great Lakes have in common.

When to use something else

If you need to understand an idea, explain it in your own words with the Feynman technique, then test yourself with active recall. A mnemonic can sit on top of that understanding, for example to keep the steps of a process in order, but it can't replace it.

If you need to keep something for months, the mnemonic alone won't do it. Reviewing at growing gaps, which is called spaced repetition, keeps it from fading.

Remembering what you read

Most of what you read doesn't come as a neat list, so a mnemonic is rarely the right tool for an article. What helps more is a question or two about each idea you want to keep, asked again after a few days.

I built Bundle to do that for you. At the end of each article you save, a Quick check asks a few questions about it. You keep the good ones as cards, and Bundle brings each card back with spaced repetition, a little before you'd forget it.

QUICK CHECK · SCIENCE Which night of sleep matters most after you study? The night after. It is at least as important as the night before, because that sleep cements what you learned. Sleep On It: How Snoozing Strengthens MemoriesShow in article

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Questions about mnemonic devices

What does mnemonic mean?

Mnemonic comes from the Greek word mnēmōn, which means mindful, and is related to Mnemosyne, the Greek goddess of memory. A mnemonic is anything that helps you remember.

How do you pronounce mnemonic?

The first m is silent: nih-MON-ik.

What's the difference between an acronym and a mnemonic device?

An acronym is one kind of mnemonic device. Mnemonic device is the name for all of them, including acrostics, rhymes, chunking, the story method, the memory palace, pegwords and the keyword method.

What is the most effective mnemonic device?

It depends on what you're remembering. For a long list in order, the memory palace has the strongest research behind it. For a short list, an acronym or an acrostic is quicker to make. For vocabulary, the keyword method helped students in the Stanford study, though the 2013 review found its benefits shrink over longer periods.