The method of loci: how a memory palace works, and what the studies show

The method of loci is a memory technique. You choose a fixed route through a place that you know well. At each stop on that route, you put a vivid image of one item that you want to remember. To recall the items, you walk the route again in your mind and find the images in the same order. The technique is also called the memory palace, the journey method or the mind palace. "Loci" is the Latin plural of "locus", which means "place".

The method works, but it does not work equally well for every task. A 2021 meta-analysis of 13 randomised controlled trials found a medium effect. In a Munich training study, 17 students practised for six weeks, 40 sessions of 30 minutes each. After the training, they recalled 62 of 72 words on average, against 25 before.

• The method of loci has two parts: the places keep the order, and the images keep the content.
• The story of Simonides, the poet who is said to have invented the method, is a legend. It comes to us mainly through Cicero and Quintilian.
• Studies show a medium effect. But most of the trials do not report how they assigned people to groups, and most of the experiments below test word lists.
• The largest gain is in order. If you must recall a list in the correct sequence, the method helps most.
• For psychology terms, the route keeps the names and their order. You learn the definitions better by retrieval and spaced repetition.

What is the method of loci?

The method of loci is a mnemonic: a technique that helps memory with a learned system. Its system has two parts. The first part is a fixed series of places that you know well. The second part is one image for each item that you want to remember. The places give the order, and the images stand for the content.

The best-known early account is in Cicero's dialogue De oratore, and it uses a picture from writing. In J. S. Watson's 1871 translation, the speaker puts the rule like this:

When you know the route, you can write a new list on it, in the same way that you write new words on a wax tablet.

Method of loci, memory palace, journey method and mind palace are names for the same technique. "Memory palace" puts the stops inside a large imagined building. "Journey method" puts the stress on the path that you walk in your mind. The principle does not change.

The method of loci is not the keyword mnemonic. In the keyword mnemonic, you connect a difficult word to a familiar word that sounds similar, and you link the two with an image.

In 2013, John Dunlosky and colleagues rated the keyword mnemonic as low utility. They wrote that it is difficult to use in some contexts. They also wrote that its benefits appear only for a small number of materials and over short retention intervals. The method of loci was not one of the 10 techniques in that review. Our guide to memorising psychology terminology explains the two techniques that the review rated highest.

How to use the method of loci: five steps

You do not need materials, only a place from your life and some time for the first round. The rules for good places and good images are more than 2,000 years old. In De oratore, the advice is to use "many plain distinct places, at moderate distances; and such symbols as are impressive, striking, and well-marked". The images must come to mind fast.

1. 1.Choose a place that you know very well, for example your home, your route to class or a building on campus.
2. 2.Set a route through that place with stops that look clearly different. Always walk the route in the same direction.
3. 3.Change each item on your list into an image that moves, is exaggerated or looks strange.
4. 4.Put exactly one image at each stop. Make the image do something with the stop, for example jump on the sofa or fall out of the fridge.
5. 5.Walk the route in your mind and recall each image without looking at your list. Do the walk again on later days.

Step 5 decides the result. An image that you put down only once fades like any other new memory, as the forgetting curve shows. Each walk is a retrieval from memory. Dunlosky and colleagues rated practice testing, which is retrieval, as high utility, and rereading as low utility.

A method of loci example: Piaget's four stages

Jean Piaget described four stages of cognitive development: sensorimotor, preoperational, concrete operational and formal operational. Exams often ask for them in the correct order. The route below is our own example. It does not come from a study.

1. 1.Front door: a small motor with blinking sensors hums on the door handle. The image stands for "sensorimotor".
2. 2.Coat rack: a surgeon hangs up her coat before an operation. The image stands for "preoperational", which means "before the operation".
3. 3.Kitchen: the same surgeon operates on a block of concrete on the kitchen table. The image stands for "concrete operational".
4. 4.Desk: the surgeon sits at your desk in formal evening dress and operates on a pile of papers. The image stands for "formal operational".

With only four stops, you can usually recall the names and their order after a few walks. But the example also shows the limit of the method. The images keep the names, not the meanings. The surgeon at the coat rack does not tell you what a child in the preoperational stage can and cannot do. You must learn that as a definition and retrieve it.

Where the method comes from: Simonides, Cicero and Quintilian

The best-known source is Cicero's De oratore, which he wrote in 55 BCE. The work is a dialogue, and Cicero does not tell the story himself. The orator Antonius, a character in the dialogue, tells it. He gives the credit to the Greek poet Simonides of Ceos, "who, as people say, first invented an art of memory".

This is the story. Simonides recites a poem at a dinner given by Scopas, a rich noble, at Crannon in Thessaly. The poem also praises the gods Castor and Pollux, so Scopas pays only half the fee. He tells Simonides to ask the gods for the rest. Soon after, a message comes in: two young men at the gate want to speak with Simonides.

Simonides goes out and finds nobody. While he is outside, the hall falls in and kills Scopas and his guests. The relatives cannot identify the crushed bodies. But Simonides remembers the place where each guest sat, so he can name each body. From this, he is said to have learned that "it is chiefly order that gives distinctness to memory".

About 150 years later, around 95 CE, the teacher of rhetoric Quintilian described how orators used the method in his Institutio Oratoria. They chose a large house with many different rooms. In H. E. Butler's translation, "the first thought is placed, as it were, in the forecourt; the second, let us say, in the living-room". The other thoughts go in order around the impluvium, the rain basin in the hall of a Roman house. As symbols, they used objects such as an anchor for a topic about the sea, or a weapon for a topic about war.

Quintilian himself doubted parts of the legend. He wrote that the authorities disagreed on the details. Was the poem for Scopas or for another man? Was the house at Pharsalus or at Crannon? He also wrote that the story became well known because of Cicero. He thought that the part about Castor and Pollux was "purely fictitious", because Simonides never mentions it himself.

Does the method of loci work? What the research shows

The method of loci improves recall by a measurable amount, but the studies have weaknesses. In 2021, Conal Twomey and Meike Kroneisen combined 13 randomised controlled trials in a meta-analysis. Most of the trials took place at universities. The groups that used the method of loci recalled more than the control groups, with a medium effect of g = 0.65. The 95% confidence interval runs from 0.45 to 0.85.

The effect stayed at a similar size when the authors corrected for publication bias and removed studies one at a time. The weakness is in the trials themselves. Most of them do not report how they made the random sequence or how they concealed the group assignment. The authors call the result "good initial support" for the method.

The Munich training study

A 2021 study by Isabella Wagner, Martin Dresler and colleagues gives exact numbers for training. The teams included the Donders Institute in Nijmegen and the Max Planck Institute of Psychiatry in Munich. The researchers recruited 51 male students of the University of Munich who had no experience with memory techniques, and they analysed 50 of them. Seventeen practised the method of loci for six weeks, 40 sessions of 30 minutes at home. Sixteen did a working-memory training for the same time, and 17 did no training.

After the training, the method of loci group recalled more than twice as many words as before. Their lead over the other two groups stayed after 24 hours and after four months. Three limits apply to these numbers. The lists were concrete nouns. All participants were young men. And the retest after four months used the same list as the test before the training, which the authors themselves name as a limitation.

Why it works: what memory champions do

In the same paper, the researchers also tested memory athletes from the world's top 50 in memory sports. After 20 minutes, the athletes recalled a median of all 72 words, and their matched controls recalled 43. In 2003, Eleanor Maguire and colleagues studied people who were known for memory feats at events such as the World Memory Championships. Their superior memory did not come from exceptional intelligence or a special brain structure. They used a spatial learning strategy, which engaged brain regions for memory and spatial memory, such as the hippocampus.

Training changes how the brain does the task. In the study by Wagner and colleagues, memory athletes and trained students showed the same pattern when they learned and recognised words. Activity decreased in the lateral prefrontal cortex and in the parahippocampal and retrosplenial cortices. This pattern was partly related to better results after four months. The authors expected the method to be strongest for learning and recalling ordered sequences, because of the mental walk through the imagined palace.

What the method of loci is good for, and where it falls short

The method of loci is strongest when order matters. In 1980, Henry Roediger had 150 students learn lists of 20 words with one of four memory techniques or with none. All the techniques helped recall. But the largest differences appeared when a word counted only in its correct position. On that score, in the immediate test, the method of loci and the peg system, a system of fixed memory words, did best.

Quintilian came to a similar conclusion. He wrote that the method is useful "if we have to reproduce a number of names in the order in which we have heard them". For a connected speech, he wrote, it is "of less service". His reason: "thoughts do not call up the same images as material things, and a symbol requires to be specially invented for them". He added that some words, such as conjunctions, cannot be shown by any symbol.

For texts, the way that you take in the text matters. Angelica Moè and Rossana De Beni tested this with 90 participants. The method of loci worked better for texts that were read aloud than for texts on a screen. For verbal rehearsal, the result was the opposite. The advantage for spoken texts was largest when the participants made their route themselves.

The delay after learning also matters. In 2000, Alvin Wang and Margaret Thomas tested how well people recalled word lists in order after a longer delay. People who organised the words or made images on their own recalled them about as well as the groups taught the method of loci or the pegword technique. Whether the words were concrete or abstract made no difference.

One applied study used course content. In a study by Ayisha Qureshi and colleagues in Pakistan, 28 second-year medical students learned three memory palaces on insulin and diabetes. On a 10-question multiple-choice quiz, this group scored 9.31 on average, against 8.10 for classmates who studied with worksheets. But the memory-palace group also had three extra sessions of 60 to 90 minutes. The authors note that the questions tested mostly recall, and that the study does not show whether the learning lasted.

Then there is the cost in time. The Munich training took 20 hours in total. A medical student on Reddit describes the same problem. In the time it took to make an image or a story, they "could have got in multiple repetitions using anki" for the same material.

Using the method of loci for psychology terms

For a psychology exam, the method of loci is most useful for lists with a fixed order. Examples are stages, phases, the steps of an experiment or the sequence of theories. The route then gives you the names and their order, as in the Piaget example. The meaning of each term is a different task.

For definitions, the techniques with the best evidence are retrieval from memory and study sessions with gaps between them. Our post on spaced repetition explains why the gaps work and how to use them for terms. The two approaches fit together. Each walk along your route is a retrieval, and you can do the walk again on later days.

Psychology World is a dictionary app with more than 18,000 psychology terms, and it helps with this second task. Look up the terms on your route and save them to one list. Then drill the list as flashcards, as multiple-choice questions once it has four or more terms, or by typing the answer. What each study mode does is set out on the home page. Then you know which stage comes after which, and also what each stage means.