This is a summary of The Mind, Explained E01: Memory (2019) by Vox. Available on Netflix.
Memory is unreliable
Some moments are so important that we believe there is a perfect recording of them etched in our minds.
Everyone has a story about where they were on 9/11.[But] about 50% of the details of memory change in a year, even though most people are convinced they’re a hundred percent right.
-Elizabeth Phelps, Neuroscientist
They may remember the gist, but not the details like who they were with and what they saw. Our memories shift and warp over time.
We have gaps, and the gaps grow larger over time. We fill up the gaps with assumptions. Our ‘episodic’ memories are actually very flexible.
With reinforcement and repetition, even false memories can be implanted. In one study (Psychological science 2015), young adults were asked to remember a crime they supposedly committed in their teens. The crimes were completely fake, but after a number of interviews full of leading questions, 70% of the subjects admitted they committed the crimes, and even came up with detailed memories that were completely false.
Unfortunately this also plays a part in eyewitness identifications.
Jennifer Thompson was taken into a room by the police and asked to identify the man that was her rapist. She wrote down a number and the police said “We thought it was him”.
By now the image of Ronald Cotton had completely ‘contaminated’ Jennifer’s memory of her actual rapist, who was also in the lineup.
By confirming it or repeating something multiple times, we can boost the confidence in a false memory.
In the US, DNA has helped overturn hundreds of convictions. 70% of those involved eyewitness testimony.
Memory is a goldmine of untapped potential
Look at the world memory champtionships.
How do they do it?
There are steps you can take to increase your memory. Including living a healthy lifestyle, not drinking so much, and getting plenty of sleep.
But mediation practice is also a major factor. In one study (in Psychological Science 2013) undergraduates were able to increase their score on verbal GREs from 460 to 520 just by taking a mindfulness meditation class.
This is possibly because meditation improves focus, and focus improves memory.
Emotion also helps memory. If you show someone a gallery of faces, they’ll remember the most emotional ones best. It’s believed that the amygdala, the emotional center of the brain which is positioned next to the hippocampus, “up-regulates” the hippocampus and allows it to form a more detailed memory.
Place and time also play a role. So do stories. A common memorisation technique involves stringing together words, numbers, or places into a narrative. In one study (Psychonomic Science, 1969) it improved memory recall from 13% to 93%.
Repuposing these natural structures of the brain is what allows memory champions to perform the feats they do.
Sample series of numbers: 546 188
546 becomes ‘SAG’, because they look similar.
166 becomes ‘TBB’ for the same reason.
The story that the memory expert creates is “a SAGgy old person is covered in TaBBouli rice”. This is also disgusting, thus emotional, and thus easier to recall.
One after the other, the sequence of numbers become words, which become the surreal parts of a story. The parts of the story are placed along a physical route that they know well – where you used to walk your dog, for instance.
Memory champions have techniques that repurpose pathways in the brain that we all have, and use. They are storytellers.
The mechanism of memory
Henry Molaison had brain surgery at 27 to treat epilepsy.
He had the hippocampus of his brain removed.
There were no physiological or behavioural changes. But he did suffer a “very grave, recent memory loss”.
He also still had old habits like knowing how to ride a bike. These have been labelled ‘Implicit memories’.
He could also tell you that the stock market crashed in 1929, as well as certain historical facts and dates, as well as numbers, and words.
But he couldn’t tell you what he had for breakfast. He could not navigate his own house, or recognise his doctors. He couldn’t remember his recent personal experiences.
When you have an experience, say performing at a recital, sensory information is processed in many different parts of the brain.
1. The sound of the cello
2. The feeling of the strings under your fingers
3. The face of your friend in the audience
4. The pang of stage fright
The medial temporal lobe, which includes the hippocampus (the part that Henry’s surgery had removed) is what pulls these experiences together, and recombine them once again when you recall a memory.
Why do we warp memories?
Henry Molaison couldn’t recall the recent past. Strangely enough, he also struggled to answer questions about the future like “What will you do tomorrow?”
Another patient with a similar temporal lobe injury described these questions as like being asked to find a chair in an empty room.
MRI scans have revealed that memory and imagination involve the same areas of the brain. When you let your mind wander, your mind switches back and forth between the two all the time.
“It’s a poor memory that only works backwards”
– Through the looking glass
The same machinery that brings pieces together to relive the past can bring in other pieces to simulate possible futures.
The flexibility that lets us remember things that never happened, that undermines the justice system, and corrupts our most vivid memories, starts to look like a superpower. Perhaps it’s a key to our success as a species.
It lets us troubleshoot upcoming experiences, think through the ways in which events might unfold, anticipate obstacles, and the best ways to deal with those obstacles.
Some scientists say that the simulation machine between our ears does something even more profound:
It weaves together memories of the past and dreams of the future to create your sense of self.