I was expecting this book to be just another think piece about learning and education, but I ended up being really surprised by how good it is. Dehaene does for the most part an amazing job at weaving lessons from neuroscience, cognitive science, and even artificial intelligence together to create a compelling narrative about how we learn and how we can take advantage of our understanding of how the brain learns to improve education.
I'll start off with some quotes I want to remember:
"Take a new group of kindergartners and put them into the passive, receptive pedagogical mode. All you have to do is give them the object while saying, “Look, let me show you my toy. This is what it does . . .” and then play the music box, for instance. One might think that this would stimulate the children’s curiosity . . . but it has the opposite effect: exploration massively decreases following this kind of introduction. Children seem to make the (often correct) assumption that the teacher is trying to help them as much as possible, and that he has therefore introduced them to all the interesting functions of the device. In this context, there is no need to search: curiosity is inhibited."
I wonder how many parents have accidentally turned their kids off of their field of specialty by doing this exact thing. Reminder to self - NEVER DO THIS TO YOUR KIDS!!!!
Another surprising point I want to remember:
"The myth of learning styles: According to this idea, each student has his or her own preferred learning style—some are primarily visual learners, others auditory, yet others learn better from hands-on experience, and so on. Education should therefore be tailored to each student’s favorite mode of knowledge acquisition. This is also patently false: as amazing as it may seem, there is no research supporting the notion that children differ radically in their preferred learning modality."
I was always told that people have different learning styles. But Dehaene really tries to emphasize that almost all children have very similar cognitive circuits, and learning techniques that work for one will work for another. I think that he pushes his myth-busting a little too far though - does he remember being a kid? There are alsl sorts of personalities and brains out there, and even if in general what works for one kid should work for all, there is undeniably a huge amount of mental diversity out there, not just in ability but in inclinations.
The book is a whole divided into three parts. The first part, which explains how modern AI works and how it falls short of human cognition, was the worst in my opinion. I almost gave up on the book actually, because it was extremely boring to me. I happen to have taken a course in exactly the sort of AI he was talking about (Bayesian models of cognition), and Part 1 was basically a pop-sci version of the course I took. Plus, it went deep enough into AI techniques that I expect it will lose a lot of readers who aren't familiar with AI, while not going deep enough to interest readers who know AI well. But he still makes some interesting points.
First, he gives nine different definitions of learning:
- adjusting the parameters of a model
- exploiting a combinatorial explosion
- minimizing errors
- exploring the space of possibilities
- optimizing a reward function
- restricting a search space
- projecting a prior hypotheses
- inferring the grammar of a domain
- reasoning as a scientist
I was impressed by this list - I think it does a pretty good job giving a lot of different AI-inspired ways of thinking about learning - but it's also a very weird presentation of these concepts, and the different definitions have a huge amount of overlap.
The next list was also interesting, a list of functions that modern AI is lacking:
- learning abstract concepts
- data-efficient learning
- one-trial learning
- social learning (the ability to use cues from other agents to speed learning)
- systematicity and language of thought (the ability to learn general laws governing an example)
- composition
I found the next part, about neuroscience, to be much more interesting, maybe because I hardly know anything about neuroscience. What struck me the most is that apparently neuroscientists have identified many brain circuits that are devoted to specific tasks, some of them much more specific and powerful than I would have imagined. For example, I already knew that there are specific areas of the brain for processing faces and language. But I didn't know that there are grid cells in the brain that are arranged in hexagons that keep track of our location in 2D space, or that there is a line of neurons in our brain that we use as a number line to compare quantities.
Another theme that Dehaene really hammers home is that literally everything we learn has a physical representation in our brains, and that we have specialized circuits for virtually everything we do. He advocates for his theory of "neuronal recycling", where, in order to learn a new task, we repurpose the most relevant specialized neural circuit to learn the task. For example, humans evolved to speak and listen, but not to write and read. So when we learn to write and read, we end up repurposing parts of our language system for writing and reading (but at no cost to language). Interestingly, literate adults are much better at many mental tasks than illiterate adults - "not only are [illiterate adults] incapable of recognizing letters, but they also have difficulties recognizing shapes and distinguishing mirror images, paying attention to a part of a face, and memorizing and distinguishing spoken words". However, I'm a little bit suspicious of this line of research. I don't know how you can fairly compare literate and illiterate adults (maybe the papers talk about this more), and maybe with more effort it would be possible to identify tasks that the illiterate adults are better at. So when Dehaene writes, "The myth of the illiterate bard who effortlessly musters immense powers of memory is just that: a myth", I have to call him out on his bullshit. Those "illiterate" bards were trained to memorize epic poems from childhood and definitely had greatly enhanced "neural "circuits" that were probably at least as impressive as our literate circuits.
Dehaene also talks about interesting results about how math is represented in the brain. We apparently upcycle our primitive built-in math circuitry to learn arithmetic and continue to repurpose those circuits to understand more and more advanced math. Even professional mathematicians rely on those same circuits to think of abstract concepts. This is actually really interesting because it shows that most people probably think of concepts, even abstract mathematical concepts, in similar ways, because those concepts are tied into the same brain circuitry. "parity, negative numbers, fractions . . . all these concepts are demonstrably grounded in the representation of quantities that we inherit from evolution.36 Unlike a digital computer, we are unable to manipulate symbols in the abstract: we always grind them in concrete and often approximate quantities."
Just by examining the brain's responses to things like phonemes, letters, or numbers, you can tell how that person was raised. The brain of someone born in China and adopted to the US, who knows no Chinese, will still activate slightly more when exposed to Chinese phonemes. The brain of someone who learned to read as a child will respond to letters differently than someone who learned to read as an adult. The brain of someone taught to read musical notes as a child responds differently to sheet music than someone who learned to read music later in life. Etc.
The last and most interesting section of the book is finally on how we learn, or the four pillars of learning:
"Attention, active engagement, error feedback, and consolidation. Four slogans effectively summarize them: “Fully concentrate,” “participate in class,” “learn from your mistakes,” and “practice every day, take advantage of every night.” These are very simple messages that we should all heed."
The "four pillars" sounds like some vapid self-help catch-phrase (the "four agreements"), but they were actually really interesting to learn about.
Regarding attention, Dehaene talks about Posner's three types of attention: "Alerting, which indicates when to attend, and adapts our level of vigilance. Orienting, which signals what to attend to, and amplifies any object of interest. Executive attention, which decides how to process the attended information, selects the processes that are relevant to a given task, and controls their execution."
It is really interesting how each of these types of attention have been carefully studied, and we know pretty well how they work. "Engaging all three types of attention" sounds technical, but at its finest, attention translates into passion - so when Dehaene says that we understand how attention works, in a way, it means that we have some understanding of how passion works. And, unsurprisingly, passion is crucial for learning. "Alerting" and "orienting" can be encouraged, and "executive attention" which is basically concentration or self-control can be trained (apparently playing music from a young age helps a lot). Concentration is also linked very closely with fluid intelligence (it affects how well we can hold and manipulate objects in our working memory), and fluid intelligence is closely linked to IQ - which is Dehaene's explanation for why every year of schooling seems to raise IQ.
One other interesting aspect of attention of its social element - children seem to have a built-in 'pedagogical stance', where they recognize when an adult is trying to teach them something and then pay very close attention to the adult to intuit what they are trying to teach. "Parents and teachers, always keep this crucial fact in mind: your attitude and your gaze mean everything for a child. Getting a child’s attention through visual and verbal contact ensures that she shares your attention and increases the chance that she will retain the information you are trying to convey." This information is sad to learn in our age of Zoom education.
Activate engagement translates to curiosity - Dehaene uses terminology that is suspiciously similar to the terminology used in "curiosity-driven reinforcement learning agents" in this section, and I'm not sure which came first, AI curiosity or neuroscience curiosity. But it's interesting either way. According to Dehaene, curiosity is the difference between what we expect (what our mental model predicts) and what we end up observing. There is crucially a sweet spot for learning. If there isn't enough stimulation/surprise, then we grow bored and our brains stop learning. If there is too much, we become overwhelmed and our brains also stop learning. Interestingly, the way that a teacher presents the material can have a huge effect on how "curious" we perceive the subject to be: "take a new group of kindergartners and put them into the passive, receptive pedagogical mode. All you have to do is give them the object while saying, “Look, let me show you my toy. This is what it does . . .” and then play the music box, for instance. One might think that this would stimulate the children’s curiosity . . . but it has the opposite effect: exploration massively decreases following this kind of introduction. Children seem to make the (often correct) assumption that the teacher is trying to help them as much as possible, and that he has therefore introduced them to all the interesting functions of the device. In this context, there is no need to search: curiosity is inhibited." (yes I think it's worth quoting this twice).
Error feedback is also surprisingly interesting. The concept is obvious - we learn more when we have the opportunity to make mistakes, or even the opportunity to possibly make mistakes - and when we receive frequent, informative, and positive feedback of what we did wrong or right. But what is interesting is that Dehaene makes the case that we shouldn't have tests and grades for measuring performance - they are not constructive. Of course, tests are still a useful pedagogical tool, but only to motivate students and get them to participate in a form of error feedback. But not as a way to punish students for not knowing the material. One way to get around this would be to have more frequent tests where the student is allowed to retake the test, receiving feedback each time, until they get all the answers right. As someone who has taken about 1 million tests over the course of my life, that makes a lot of sense to me.
Consolidation is ALSO surprisingly interesting! Dehaene talks mainly about two things - spaced repetition learning and sleep. Spaced repetition learning is great, and I need to use Anki more to memorize and practice things. And sleep is even more important than I thought - Dehaene really believes that our brains are generative models, and that sleep is used to sample experiences from our generative model. He seems to think that sleep's main function is to help us learn, because during the night our brain can sample experiences from its generative model much more rapidly than we can experience things during the day, allowing us to learn and commit things to memory as we sleep.