The Forgetting Machine

Our brain has about 100 billion neurons, each wired to another 10,000 with a variety of firing patterns. Given the sheer number of neurons, surely we can record everything and store all our memories?

But we don’t. And what we record is not 100% accurate, which may not be a bad thing. Neuroscientist Rodrigo Quian Quiroga shares why in his book The Forgetting Machine : Memory, Perception, and the “Jennifer Aniston Neuron”.


The author, a noted brain scientist, takes the reader on an exciting whirlwind tour of vision and memory. His take-home message is that our brains don’t faithfully record the pixels making up any one scene nor do they recall anything but a minute fraction of life events. Most of what we do, see, and remember is filtered, interpreted, and inferred.

Christof Koch, Chief Scientist and President, Allen Institute for Brain Science, Seattle

Christof Koch nicely summarizes this engaging and easy-to-read book1. Among the many topics, this book covers the different types of memories, how we store them, and how much we remember.

By now it is quite commonly known that what we perceive of reality is a mere representation of it. The sheer amount of external stimuli has increased exponentially but it’s not that only.  Essentially a rather small percentage of information is actually received by our senses and a small percentage of that is stored as long-term memories.

Long Term Memories

What becomes long-term memory depends partially on repetition, which is what rote learning in school is about. This is an arduous practice that requires discipline and time.

Memories also stick because of associations. A better approach to education, rather than a bombardment of curriculum topics, is to cover a topic in a variety of contexts and associations to consolidate the information in a deeper and more robust way. These associations can also address the different ways people learn.

What Fires Together Wires Together

The handy phrase “What fires together wires together” means that neurons that encode similar information are more likely to fire together because they are connected. The more neurons fire at the same time the stronger their connections, forming Hebbian cell assemblies. These are groups of interconnected neurons with different memories. Presenting a topic in different manners creates opportunity for additional associations.

studying memories

Also by broadening the ways a topic is taught, we are increasing the chances of engaging a student’s interests and pique their curiosity. Research shows that what we remember in the end is the schema we have created, based on our own interpretations and associations when we are exposed to the information. Learning and remembering therefore is very individual.

Here are some books you may be interested in :: The Hungry Mind | The Origins of Curiosity in Childhood by Susan Engel, Curious | The Desire to Know & Why Your Future Depends on It by Ian Leslie.

The Jennifer Aniston Neuron

The author neuroscientist Rodrigo Quian Quiroga (along with the research team) discovered what is now known as the “Jennifer Aniston neuron”. In his research, he found that the subject had a neuron that responded to seven different photos of the actress and not to photos of other celebrities, non-celebrities, places, and animals.

The same subject also had a neuron that responded only to the Leaning Tower of Pisa, another only to the Sydney Opera House, and another only to Pamela Anderson, etc. These are “concept neurons”, which are key to the formation of memories.

No, we don’t all have neurons that fire to Jennifer Aniston.

The “concept neurons” are so called because they respond to a specific concept, such as Jennifer Aniston or Halle Berry, whether the subject was shown the stimulus’ photo, line drawing, their name written on the screen or voiced by a computer.

By pairing different photos, concept neurons begin firing at the “new” photos, a finding that shows how quickly we can encode associations and form memories. It’s still early days on understanding this and it sure is interesting.

How Resilient are Our Memories?

If you watch movies or shows like Bull, you’ll have come across the idea that witness accounts are not as reliable as we would like them to be. Just the way a question is asked, a leading question perhaps, the recall can be altered.

In psychologist Elizabeth Loftus’ experiment, people were asked a series of questions after watching a video of an accident. Questions included what are the highest speed estimates and whether there was glass at the scene. The answers differed whether words such as collided, bumped, smashed or contacted were used in the question. A higher percentage of people believed there was glass when the word smashed was used, versus 14% when the word hit was used. There was no glass.

Memories are malleable and easily corruptible during the consolidation process. This is something we should remember before we go accusing someone.

In our society, we are expected to be sure and perhaps “I don’t know” can be de-stigmatized.

The Internet & Memory

Rodrigo Quian Quiroga also addresses the question of the internet which has really been a game changer. He brings up how Socrates was concerned writing would erode the powers of memory, and oration.

In Phaedrus, Plato shares the story of how King Thamus of Egypt rejected the gift of letters through the dialogue between Socrates and Phaedrus – “you give your disciples not truth, but only the semblance of truth; they will be hearers of many things and will have learned noting; they will appear to be omniscient and will generally know nothing; they will be tiresome company, having the show of wisdom without the reality.”2

Book to check out : Proust and the Squid by Maryanne Wolf and Catherine J Stoodley

Why do we bother learning dates of wars, the reigns of dead men, and the era of the Northwest Passage when we can so easily google it?

The internet provides endless info. Haven’t we all lost a few hours on the internet, be it youtube, Facebook, or the reviews and conjectures of Infinity War, the ending of Inception, or who Rey parents are

The internet and social media are teaching us to read superficially, jumping from topic to topic with the ease of a button click. Pre-internet, we had to look up each topic in the Encyclopedia or head out to the library to search out different books. Sometimes even waiting for on-hold books to come in. It was anything but instantaneous. We had to dig for it. We had to work for it. The effort makes learning stick.

Is our comprehension degrading and our field of vision narrowing by scanning specifically for what we (think) we need?

The author sees it as how much we remember versus how we remember. The internet may provide us with scores of information. We are the ones to process the information, select various ideas, draw conclusions, consolidating and upgrading our perspective and understanding of ourselves and the world around us.

While he is all for delegating storage to our many gadgets, he reminds us not to succumb to or be seduced by the “frenzied rhythm” of the internet. Question – are you still able to sit down and read a book or a magazine? Do just that one thing. Not while listening to music, checking your social media, or grabbing a bite. Are you able not to multi-task?

Reading a book learning

So back to the forgetting brain. One of the questions Rodrigo Quian Quiroga raises is – are we still us if we lose our memories? For people who know someone with Alzheimer’s, they would say no. In the book, the author looks at both the neuroscience and the philosophy underlying this question and it is not an easy question to answer. As part of his inquiry, he looked at the topic “can androids feel?” The fact is that our memories are constantly changing; whenever we touch on it, it is inevitably altered.

The Man Who Could Not Forget

Rodrigo Quian Quiroga shares the story of Solomon Shereshevskii who could not forget a single thing and later became a professional mnemonist.

He was tested and later studied for three decades by psychologist Alexander Luria. Solomon Shereshevskii’s incredible feat included repeating lists of as many as 70 items in any order, from any starting point. After reading anything, even meaningless syllables, he continued to see them in his mind.

The reason for his photographic memory? He used the method of loci and he had strong synesthesia.

The method of loci was used by ancient Greeks and Romans. In Sherlock, both Sherlock Holmes and Charles Augustus Magnussen have mind palaces, the method of loci to store vast amounts of information.

For some people, synesthesia means associating two senses. For Solomon Shereshevskii, it was several senses. The number 1, for example, was a proud, well-built man.

The Function of Forgetting

So you can imagine how full on it was for him.

Would not forgetting be a fantastic thing, especially for passing school tests and never ever forgetting where your car keys or phone are? Maybe be the Jeopardy champion?

The problem with never forgetting was that while Solomon Shereshevskii could recall what he remembered, he could not understand it.

Because he never forgot, reading a novel was impossible as each word brought up different associations. He even found it difficult to remember faces because the different expressions confused him and he could not follow a conversation because he was distracted by the changing tones of a voice. He could not think abstractly, and that is part of what makes us intelligent and human.

The Real Rainman

Another example Rodrigo Quian Quiroga shared was Kim Peek, on whom the movie Rain Man with Dustin Hoffman was based. Probably because of that movie most of us are now familiar with the concept of a savant and the incredible memory recall of someone like Kim Peek. The only books he read were factual, and without ambiguity.

Both Solomon Shereshevskii and Kim Peek and people like them are much more like a computer which records perfectly. It’s wondrous.

This is Our Brain

What actually happens for most of us, as we know it, is that the brain “focuses on relatively sparse information and extracts meaning by processing it redundantly, many times and in many different ways….. We assume from past experiences the perceptual information not registered by our brain; they are the assumptions that we constantly make and that sometimes lead us to be fooled by optical illusions or false memories.”3.

For survival reasons, we only needed to see the vague shape of a tiger to know it’s time to run, or hide. This comes from the brain’s evolved ability to parallel and redundantly process and to scan and pick out the most important and salient information, to extract meaning. “Our capacity to manage and relate abstractions, coded by concept neurons in the hippocampus, is the basis of our memory – and, perhaps the cornerstone of what makes us human.”4

1 Rodrigo Quian Quiroga wrote this book with a sophomore student in mind to pique their curiosity about neuroscience and share what’s going on in this interesting field these days.
2 Phaedrus by Plato as translated by Benjamin Jowett. As quoted in Quiroga (2017). p.92.
3 The Forgetting Machine by Rodrigo Quian Quiroga. Translated by Juan Pablo Fernández. BenBella Books, 2017, p 154-155.
4 Ibid., p 156.