Sherlock’s Mind Palace Technique Explains “Memory Athletes'” Incredible Recall

A recall technique used by Benedict Cumberbatch’s  modern-day interpretation of Sherlock Holmes can create enduring memory enhancement that remains intact four months later, according to a new study.

The findings, published by an international team of researchers in Science Advances, examined a cohort of the world’s top “memory athletes” – individuals who have shown mastery of mass information recall – and a group of non-expert participants.

The memory athletes all showed exceptional ability in using the method of loci, a memory-enhancing mnemonic device originally devised in Ancient Greece. Study co-author  Isabella Wagner from of Radboud University Medical Center in the Netherlands explained to Technology Networks that although the loci technique has been shown previously to boost memory, unanswered questions remain: "There have only been a handful of studies exploring how [the loci technique] works in the brain and whether "memory champions" are actually different from other people or better at something that can be trained." 

Memory vs Mensa

The method of loci technique is applied outside of our TV screens in events such as the World Memory Championships, where competitors flaunt their ability to recall strings of individual words. Some top athletes from the championships were tested in an initial study against a group including several members of the high-IQ society Mensa. The athletes flexed their memory muscles, recalling 72 words on average from a list they were shown previously, versus just 43 for the control group.

The researchers then divided 50 volunteers with no knowledge of the method of loci technique into three groups. One cohort was trained in the art of loci mnemonics over a six-week period, whilst a second group was given working memory training. A final, passive group was given no training at all.

Memory ability and brain function were assessed before and after these training regimens whilst participants underwent MRI scans. Participants allocated to the method of loci training group were better at recalling words from a list after 20 minutes (which is commonly how memory athletes are assessed in competition), averaging 62 words, versus 42 words for volunteers given working memory training and just 36 words for volunteers with no training.

Later, the method of loci group performed better than other groups at recalling words after 24 hours, racking up 56 words versus 30 and 27 for the working memory-trained and untrained groups. "The technique helps to boost long-term memory," said Wagner. 

To confirm this, the team analyzed a subset of volunteers from each group who were asked to return to the lab four months later and take the same memory tests. The volunteers who had studied method of loci once again outperformed the other groups – they were able to recall 20 more words than they could pre-training, whereas participants given working memory training had lost all the benefits of their training.

Brain changes in the “memory palace”

To investigate whether this evidence was backed up by physiological changes in the brain, the team examined their participants’ brain activity data, recorded from MRI scans. Before and after training, all three volunteer groups were presented with previously unstudied words and asked to commit them to memory. After training, the method of loci volunteers were asked to deploy their newly learned technique, placing the words that they had seen in their “memory palace”. Whilst the team expected to observe increased activity in their trained group, especially in regions related to memory recall such as the hippocampus and medial temporal lobe, they discovered that there was a decrease in activation in these regions. Supporting this finding, their memory athletes also had lower brain activation than the non-expert control groups.

Interestingly, whilst the levels of activation decreased, levels of brain connectivity between the hippocampus and the neocortex, the site of higher thinking in the brain, increased. The authors suggest in the paper that these findings are in line with changes in “neural efficiency,” a hypothesis that proposes that intelligent or highly skilled individuals display lower brain activity during cognitive tasks.

How else might the method of loci technique improve memory? Wagner and colleagues suggest that the technique’s focus on association between words and novel locations could help release hormones from the brainstem that trigger changes to the connections between brain cells. These changes would help consolidate memories of the words stored in the loci mind palace.

Overall, the study shows that the mnemonic method of loci approach could be key to developing an extraordinary memory, not just "memory champions" or TV detectives. "This is a technique that can be learned by everyone," commented Wagner. "Even without constant training, I think you can very quickly find small successes with it." Wagner has used method of loci herself, to remember a grocery list. To recall milk and eggs, Wagner's mind palace, a mental version of her house, has been populated with cows and chickens in set rooms. To effectively walk a memory path, the "palace" should be a familiar location and the associations "should be as weird and novel as possible," concludes Wagner.