Sunday, May 12, 2019

Why books and lectures/school don’t work, according to Andy Matuschak

Why books don’t work. Andy Matuschak. Blog, May 11 2019.


Picture some serious non-fiction tomes. The Selfish Gene; Thinking, Fast and Slow; Guns, Germs, and Steel; etc. Have you ever had a book like this—one you’d read—come up in conversation, only to discover that you’d absorbed what amounts to a few sentences? I’ll be honest: it happens to me regularly. Often things go well at first. I’ll feel I can sketch the basic claims, paint the surface; but when someone asks a basic probing question, the edifice instantly collapses. Sometimes it’s a memory issue: I simply can’t recall the relevant details. But just as often, as I grasp about, I’ll realize I had never really understood the idea in question, though I’d certainly thought I understood when I read the book. Indeed, I’ll realize that I had barely noticed how little I’d absorbed until that very moment.

I know I’m not alone here. When I share this observation with others—even others, like myself, who take learning seriously—it seems that everyone has had a similar experience. The conversation often feels confessional: there’s some bashfulness, almost as if these lapses reveal some unusual character flaw. I don’t think it’s a character flaw, but whatever it is, it’s certainly not unusual. In fact, I suspect this is the default experience for most readers. The situation only feels embarrassing because it’s hard to see how common it is.

Now, the books I named aren’t small investments. Each takes around 6–9 hours to read. Adult American college graduates read 24 minutes a day on average, so a typical reader might spend much of a month with one of these books. Millions of people have read each of these books, so that’s tens of millions of hours spent. In exchange for all that time, how much knowledge was absorbed? How many people absorbed most of the knowledge the author intended to convey? Or even just what they intended to acquire? I suspect it’s a small minority


I’m not suggesting that all those hours were wasted. Many readers enjoyed reading those books. That’s wonderful! Certainly most readers absorbed something, however ineffable: points of view, ways of thinking, norms, inspiration, and so on. Indeed, for many books (and in particular most fiction), these effects are the point.

This essay is not about that kind of book. It’s about explanatory non-fiction like the books I mentioned above, which aim to convey detailed knowledge. Some people may have read Thinking, Fast and Slow for entertainment value, but in exchange for their tens of millions of collective hours, I suspect many readers—or maybe even most readers—expected to walk away with more. Why else would we feel so startled when we notice how little we’ve absorbed from something we’ve read?

All this suggests a peculiar conclusion: as a medium, books are surprisingly bad at conveying knowledge, and readers mostly don’t realize it.


Why lectures don’t work

We’ve been discussing books so far, but have you ever had the same type of experience with a lecture? It’s easy to attend a lecture and feel that you understand, only to discover over that night’s problem set that you understood very little. Memory feels partly to blame: you might sense that you knew certain details at one time, but you’ve forgotten. Yet we can’t pin this all on memory. When you pull on certain strings from the lecture, you might discover that you had never really understood, though you’d certainly thought you understood during the lecture.


Like books, lectures can be entertaining or influential; like books, lectures do seem to work… sometimes, for some people. But you probably don’t believe that lectures are a reliable way to convey knowledge.

Books don’t work for the same reason that lectures don’t work: neither medium has any explicit theory of how people actually learn things, and as a result, both mediums accidentally (and mostly invisibly) evolved around a theory that’s plainly false.

To illustrate what I mean, I’ll try to draw on your own learning experiences. You’ve probably discovered that certain strategies help you absorb new ideas: solving interesting problems, writing chapter summaries, doing creative projects, etc. Whatever strategies you prefer, they’re not magic. There’s a reason they work (when they do): they’re leveraging some underlying truth about your cognition—about the way you think and learn. In many cases, the truth is not just about your cognition but about human cognition in general.

If we collect enough of these underlying “truths,” some shared themes might emerge, suggesting a more coherent theory of how learning happens. We’ll call such theories cognitive models. Some learning strategies suggest the same model; others suggest conflicting models. Some of these models are empirically testable; others aren’t; still others are already known to be false. By focusing on these models, instead of a herd of one-off strategies, we can seek more general implications. We can ask: if we take a particular cognitive model seriously, what does it suggest will (or won’t) help us understand something?

That’s an important question because it’s hard to convey knowledge. Most lecture attendees don’t absorb the intended knowledge; most book readers don’t absorb the intended knowledge. Failure is the default here. So if you hope to help others understand things, you had better draw on some great ideas about how people learn. It would be nice if this weren’t true. It would be nice if one could simply explain an idea clearly to someone, then trust that they’ve understood it. Unfortunately, as you’ve likely seen in classrooms and in your own life, complex ideas are rarely understood so automatically.

Lectures, as a medium, have no carefully-considered cognitive model at their foundation. Yet if we were aliens observing typical lectures from afar, we might notice the implicit model they appear to share: “the lecturer says words describing an idea; the class hears the words and maybe scribbles in a notebook; then the class understands the idea.” In learning sciences, we call this model “transmissionism.” It’s the notion that knowledge can be directly transmitted from teacher to student, like transcribing text from one page onto another. If only! The idea is so thoroughly discredited that “transmissionism” is only used pejoratively [...].

Of course, good lecturers don’t usually believe that simply telling their audience about an idea causes them to understand it. It’s just that lectures, as a format, are shaped as if that were true, so lecturers mostly behave as if it were true.

If pressed, many lecturers would offer a more plausible cognitive model: understanding actually comes after the lecture, when attendees solve problem sets, write essays, etc. The lecture provides the raw information for those later activities. Great: that’s a real model, and parts of it are supported by cognitive science. But if we’d begun with this model, would we have chosen live, ninety-minute speeches to convey raw information for a problem set?

Listeners’ attention wanders after a few minutes, so wouldn’t we want to interleave the problem-solving sessions with the lecture? Live speeches can’t be paused or rewound, so aren’t they awfully lossy for conveying raw information? People can read much more quickly than a lecturer speaks, so wouldn’t text be more efficient? And so on—it’s already clear that the traditional lecture format isn’t particularly informed by this model.

The lectures-as-warmup model is a post-hoc rationalization, but it does gesture at a deep theory about cognition: to understand something, you must actively engage with it. That notion, taken seriously, would utterly transform classrooms. We’d prioritize activities like interactive discussions and projects; we’d deploy direct instruction only when it’s the best way to enable those activities. [...]

In summary: lectures don’t work because the medium lacks a functioning cognitive model. It’s (implicitly) built on a faulty idea about how people learn—transmissionism—which we can caricaturize as “lecturer says words describing an idea; students hear words; then they understand.” When lectures do work, it’s generally as part of a broader learning context (e.g. projects, problem sets) with a better cognitive model. But the lectures aren’t pulling their weight. If we really wanted to adopt the better model, we’d ditch the lectures, and indeed, that’s what’s been happening in US K–12 education.


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