New “Beside Discovery” additions

I recently added a few items to my “messy micro-histories of science” section here, reproduced below:

Anthropologist Hugh Gusterson wrote “A Pedagogy of Diminishing Returns: Scientific Involution across Three Generations of Nuclear Weapons Science” (2005) about the strange sort of inward-turning and withering of nuclear weapons science in the post-testing era. That field (as well as national labs and megaprojects more generally) often seems to be dramatically idiosyncratic or even dysfunctional — but as with many of those dramatic features, the process Gusterson describes is a magnified version of something that plays in some form in all sorts of labs as fads and funding wax and wane. (Not to mention that perhaps most actual work in science is done by people in temporary and training positions, who today are very likely to leave science, taking a great deal of tacit knowledge with them.)

The Hanbury Brown and Twiss experiment is an interesting case where classical electromagnetism easily produces a correct answer, while the quantum mechanical explanation involves important subtleties. It caused controversy when it was performed in the 1950s, with critics saying that if the results were correct they would call for a “major revision of some fundamental concepts in quantum mechanics.” This was not at all true, as some people recognized immediately. From a certain perspective the quantum theory necessary for a correct explanation had been developed decades earlier (doubly true for the debate’s reappearance in the 1990s), but certain distinctions, particularly in source and detector physics, had not yet been made relevant by experiment. (Additionally, Dirac had written something that made a certain sense in the context of the 1930s but confused many physicists trying to apply it to understanding HBT: “Interference between different photons never occurs.”) The HBT paper in 1956 was then one of the motivations for developing theory along these lines, laying the foundations for quantum optics. I may write more about it someday, but for now The Twiss-Hanbury Brown Controversy: A 40-Years Perspective is a good overview.

A Half Century of Density Functional Theory (2015) celebrates a theory exceptional in that it in some sense fits the “discovery” narrative very well — it wasn’t at all “in the air” as these things often are. On the other hand, DFT’s value took some time to be recognized, especially among quantum chemists, for somewhat arbitrary reasons. [Additional links are quotes.]

Exercise #4

Consider the following experimental results:

People who became vegetarians for ethical reasons were found to be more committed to their diet choice and remained vegetarians for longer than those who did so for health reasons.

Loyalty to expert advisers (doctors, financial advisors, etc.) leads to higher prices but not necessarily better services.

Smokers who viewed ads featuring messages about “how” to quit smoking were substantially more likely to quit than those who viewed ads with reasons “why” to quit.

In adults, creativity was substantially inhibited during and shortly after walking (either outdoors or on a treadmill) as compared to sitting.

Answer each question before scrolling down and reading the next, because of SPOILERS:

1. How do you explain these effects?

 

 

 

2. How would you have gone about uncovering them?

 

 

 

3. These are all reversed, and the actual findings were the opposite of what I said. How do you explain the opposite, correct effects?

 

 

 

4. Actually, none of these results could be replicated. Why and how were non-null effects detected in the first place? Answers using your designs from (2) are preferable.

 

 

 

Final spoilers below.

 

 

 

For the real findings, see Useful Science (1234), which is Useful as a source of further exercises, at least. Some of the four are indeed reversed, but as far as I know I made up the part about replication. Reflect on the quality of your explanations and on any feelings of confusion you noticed or failed to notice. I apologize for lying; it was for your own good.

Extra credit: Follow the links to find the original papers. Compare your proposed test, and determine whether your alternative explanations were ruled out.

Beyond Discovery

Beyond Discovery™: The Path from Research to Human Benefit is a series of articles that trace the origins of important recent technological and medical advances. Each story reveals the crucial role played by basic science, the applications of which could not have been anticipated at the time the original research was conducted.

The National Academy of Sciences ran this project from 1996 to 2003. The website went offline in early 2013 and as of June 2014 is still “under construction.” [2015 update: that link now leads to a page with all the articles as PDFs! Except the MRI one, for some reason.] You can [also] find all twenty articles in the Internet Archive, but it’s kind of a pain to navigate. So I’ve gathered them all here.

The articles (each around 8 pages) are roughly popular-magazine-level accounts of variable quality, but I learned quite a bit from all of them, particularly from the biology and medicine articles. They’re very well written, generally with input from the relevant scientists still living (many of them Nobel laureates). In particular I like the broad view of history, the acknowledged scope of the many branches leading to any particular technology, the variety of topics outside the usual suspects, the focus on fairly recent technology, and the emphasis bordering on propagandist on the importance and unpredictability of basic research. It seems to me that they filled an important gap in popular science writing in this way. Links, quotes, and some brief comments follow.

Continue reading

Pendulum

When she lost her faith I said that falsehood yes feels true from inside, and in that moment she was born again.


There’s an old joke. Two lovers freed a genie who would grant them one wish. They wished to switch bodies for a day, so that they might better know each other and thereby grow closer. The genie declared with a sweep of his arm that their wish was his command.

Nothing happened, because dualism is false.


She’d had the bad habit of wandering during the round. All the other matches were always so interesting. Even when she was losing, as did sometimes happen, she couldn’t bring herself to think if it wasn’t her move. Strange what the clock does, and maybe doesn’t do, to your brain.

Once, against a particularly slow adversary, she wandered the entire tournament hall, subitizing some boards and puzzling absorbed over others. She stood finally behind one hopeless player, where for two minutes she invented variations that might save him before she realized she was standing behind her own opponent.

Of course, that was nothing like this. After all, she lost that game.


It started with a Glass knockoff that sold in pairs. See through your partner’s eyes. Experience their field of vision projected onto yours. Nobody cared.

(Well, it saw some success in the adult entertainment industry.)


She went to university to study chemistry, planning-without-planning to go to medical school. We met in P-chem, which I was auditing because I wanted to see just how physical it was. I accidentally convinced her to take quantum mechanics from the Physics department instead. She wound up doing a PhD in physics. These days she does research that sounds more like neurobiology.

If there’s an analogy to be found here, it’s facile, to say the least.


That part about neurobiology is relevant, though. She did a postdoc working on directly shared sensory experience in mice. Biocompatible, electromagnetically and chemically sensitive implants, plus some clever algorithms for inter-nervous-system compatibility. She used to tell me it was easy compared to what was coming next.


She told me about a book she read. It said:

“You must push your head through the wall. It is not difficult to penetrate it, for it is made of thin paper. But what is difficult is not to let yourself be deceived by the fact that there is already an extremely deceptive painting on the wall showing you pushing your head through. It tempts you to say: ‘Am I not pushing through it all the time?’”

She liked that so much she framed an extremely deceptive facsimile of the page on which it appeared and hung it by her desk.

But I hope you don’t think that explains anything.


Uploading turned out to be a dead end, to the chagrin of materialists everywhere. You could store all of the relevant static information, but it never became practical to evolve that information in time outside of a brain. So what are you going to do? Take fine enough timeslices and you can relive experiences by playing them back. And not just sensory experiences—even your thoughts at the time could be reproduced. Motor activity would be deliberately excluded, but proprioception could still be overridden. Your present conscious life would keep going, with part of you aware that you were merely observing; but as long as the present you didn’t interfere, you could without hyperbole relive your past.

A couple early consumer products tried it (isolation tank sold separately), once they figured out how to record and play back without surgery. Received breathless media coverage and millions in venture capital. Went out of business a year after launch, under the pressure of some monster class-action suits. Turned out the physical changes in the brain meant that the same signal eventually produced a different experience, one which was often bizarre and traumatic. The backups didn’t get corrupted—but the hardware did.


She kept a grandfather clock in her dining room. For the pendulum, naturally. So well-behaved at small angles, but force it hard enough and it never retraces its path in phase space. You can repeat a position, but only if you arrive with a different velocity. You can relive a velocity, but never quite in the same place you were the first time. Your only regularity is the fractal structure of your history, your strange attractor.

A terrible metaphor, as you can see. Her clock didn’t even work.


Anyway, that was where she came in: how to account for these physical changes? She’d already figured it out for the basic senses; the architecture was similar enough between individuals. With a mountain of data and graduate students she worked out a system of translation between different versions of an evolving brain.

From there it wasn’t long before she could stream all conscious experience and subconscious activity from one individual to another. The genie just hadn’t been creative enough.


We fought, once, about her poetry. She was struggling, and I dared suggest that she was trying to capture something that wasn’t there. Better to take joy in the real. Like Feynman on the beauty of a flower, or Wallace on the truth in a cliché.

She said:

How many people do you think nod smugly along to that Feynman quote, as though it vindicates their own insipid tastes. As though all art is as juvenile as their high school blue period, and there’s no post-Feynman looking down on them from the other side of the dialectic double helix. Like now that they’ve learned what words really mean and what reality really is they can know instinctively that there’s no materialist consequentialist boundary where art versus science is a meaningful worthwhile framing. Wallace at least knows that to be bullshit, that there’s a reason people talk about things that way. He understands what it means to sublate if anyone does. But he gets interpreted in just as regressive a way as Feynman, like our cynical sophistication failed us and we have to retreat back to where all truth is cliché. Like it wasn’t just another superstimulus, like the taste isn’t still adaptive in the right form and when better informed. But I guess I can explain all day that something not being literally true or materially there isn’t a reason not to write about it and you’ll still fold me with the pre-moderns until you’ve lived through the syncretism yourself.

How my heart aches. I said: Oh I thought you thought Hegel was nonsense.


The moment it was declared safe for humans, she wanted to try it. And who would she trust to stream from?

I asked only that it be mutual.

If you really wanted to understand, you’d have to experience it for yourself. I’m not even sure it would work to stream the experience from someone else. At first it’s just noisy. It takes time to adapt, to figure out how to listen. To see through your partner’s eyes. To think their thoughts, or your brain’s versions of their thoughts. To resolve a disagreement semi-automatically just by finally really seeing each other’s perspective. To mentally ask a question, and for your partner to involuntarily recall the answer in response. To notice the same happening to you, and to then realize how terrifying it is. But then also that your partner isn’t terrified, doesn’t see it as coercive, is sad that you don’t trust her that way. To demand that she turn this thing off before that difference and all your precious differences are resolved by this alien process so mutual that neither of you can control it. To never speak of it again.


There wasn’t much more to it. The two of us, I mean. I keep reliving these stories I collected in the too-short time that we were connected, even though I know they don’t explain anything that happened or might happen yet. There’s no such thing as explanation, after all. But perhaps the pendulum can be pushed back.

Link: In Praise of Passivity

Normally the 2012 publication date would make this too recent for benthic canon, but Michael Huemer’s In Praise of Passivity was written in my heart long ago. The abstract:

Political actors, including voters, activists, and leaders, are often ignorant of basic facts relevant to policy choices. Even experts have little understanding of the working of society and little ability to predict future outcomes. Only the most simple and uncontroversial political claims can be counted on. This is partly because political knowledge is very difficult to attain, and partly because individuals are not sufficiently motivated to attain it. As a result, the best advice for political actors is very often to simply stop trying to solve social problems, since interventions not based on precise understanding are likely to do more harm than good.

I hope you’re already familiar with the anxiety of epistemology that observing polarized debates ought to induce, but Huemer gives an unusually concise, thorough, and well-documented survey of the landscape. This is, as always, not to say that I agree with every word of it—but this is largely a matter of degree, in particular of the extent to which the best we can do is to set our hearts on doing nothing and thus leave nothing undone. The author risks handing readers a lofty principle that’s too easily used to argue one position and dismiss others without ever engaging the positions’ particulars. But I take these ideas as an unspoken starting point for discourse. Or I would, were it ever worthwhile for me to talk to someone about politics. Anyway, it probably doesn’t work if I leave it unspoken.

Exercise #3

Apply the Casuist’s Razor to an explanation, judgment, or argument of your choice. Suggestions from answers to “What is your favorite deep, elegant, or beautiful explanation”: Marti Hearst, Stuart PimmLaurence C. SmithEvgeny Morozov. Bonus points for an evenhanded application to your favorite argument on copyright, piracy, software patents, drug use, abortion, free speech, or another potentially value-laden topic. What phenomena are correctly explained, or what actions are correctly judged? In what cases or in what sense does the opposite explanation or principle correct? What would a more complete account or judgment look like? (How do you reconcile your previous answers? What details do you need to consider? What are the relevant empirical predictions or consequences?)

Extra credit: Apply the Casuist’s Razor to itself. What explanations (etc.) does it correctly identify as good? What is the opposite principle, and what explanations does that correctly identify as good? What details of those explanations are needed to make these accounts compatible?

The Casuist’s Razor

“Casuistry” is today a near synonym for “sophistry”: a certain kind of intricate, deceptive reasoning; highly pejorative. The word originally referred to case-by-case moral analysis (and, as philosophical jargon, still does). But the casuist, evidently, abused the rich particularities offered by reality to justify his prior intuitions. With a torrent of excuses and exceptions he eroded the barrier between right and wrong. This was unacceptable.

If casuistry has fallen out of fashion, then principled reasoning is our new rising star.a Our most successful scientific theories—physics and evolution in particular—are seen as having succeeded on the strength of their simplicity, their ability to explain a wide range of phenomena using only deep, universal principles. The direction of causality is unclear, but today’s intellectual discourse is saturated with a similar reductionist impulse, which I contend is as much aesthetic as practical. Consider the 2012 Annual Question from Edge.org: “What is your favorite deep, elegant, or beautiful explanation?” One wonders whether that disjunction was really necessary.

There are epistemological advantages to keeping your theories small. Derive all your judgments from simple premises, and you no longer risk overfitting. An argument with fewer moving parts requires less justification, is less vulnerable. Meta-level considerations can pinpoint common patterns to achieve vast compression. Hail Occam’s Razor.

Continue reading

  1. In this metaphor, stars take centuries to rise.  (back)

The Stargazers

On this next world, the dominant animal phylum shared a remarkable sense organ: a forest of piezoelectric peptide nanotubes, sheltered in a front-facing cavity, to be subjected to deformation by the oscillating pressure front of a sound wave, producing an information-dense electrical signal carried to the brain and experienced as sound. In this the creatures were not so different from evolved humans, if superficially exotic.

But, remarkably, many species developed the ability to excite these tiny structures by an act of will. The reciprocity of the piezoelectric effect, aided by a fortuitous matching of acoustic and electric impedances, meant that the same electrical signal, when directly applied to the forest, produced the same oscillatory deformation, which in turn pushed the air from the aural/vocal cavity in acoustic waves. To the extent that the mechanical response faithfully preserved the information content of the oscillating pressure, the organ could produce that same sound. This was the only method of vocalization ever evolved on this planet.

The organ was not so versatile as even the microphones and speakers of our Earth’s twentieth century; we would hear in its song mostly an indistinct rasp and buzz. But to those properly equipped to listen–which is to say, those equipped as well to sing–the variety of shapes and textures was as rich as that of any orchestra.

At first I felt certain that this was the solution, the key development that would finally allow humane life to flourish. For how could misunderstanding occur, when to hear was to know the very impulses that shaped the words! What lies could propagate, when their promulgation was not merely ontologically but neurally reciprocal with their perception? Even the most adept liar knows the lie, and subtle cues slip into the voice. Every utterance would betray intent.

As I became habituated to the sounds, I marveled at the variance in voices. It was ages yet before the implications of this individuality fully dawned on me. Language did indeed develop and spread rapidly in the most intelligent species inhabiting this world, since neural commonalities played an even larger role than in communication among evolved humans.

But to my eventual dismay, I found vicious argument and deception prominent in the discourse of the budding civilization–perhaps, I was reluctant to admit, even more so than in familiar species! I studied these beings intently, searching for the source of the psychological defect that had overwhelmed their natural advantage of true communication.

It was not until a much later stage in their civilization that I found the answer to my confusion, in a place where I in my idealism had not thought to look. For all the lovely gradations of sonic texture, the distinctions among the sexes, the patterns of maturation of an individual’s vocal/aural forest and cavity: these served to drive individuals apart as strongly as the commonalities drew them together. The listener did not experience the very impulses that had driven the speech, as I had first assumed, but rather an analogue according to the listener’s own sense organ and neural circuitry.

This need not have been disastrous, had the individual differences been great enough that a layer of indirection between hearing and understanding was required, as in the vast majority of intelligent species. But for these beings, the vocal/aural system was deeply entangled with the rest of the brain, and the boundary between linguistic and abstract thought had vanished. Or, if there was a true distinction, then one invoked the other automatically.

Evolution had thus capped the individual variation: too far astray, and a mutant was unintelligible and itself heedless to the cries of its folk. This did cause some strife when long-separated branches of the species later made contact, but it was a bland and straightforward strife. The conflict in which each side sees the other as incomprehensible and monstrous is a morality play that you do not need me to repeat. The truly chilling folly arose from the barely-imperfect correspondence between minds within a society.

Imagine that, brimming with novel and nuanced insight, you made to convey your wisdom to me, but all that I heard was my own inner monology generating those thoughts. Without even a chance to notice the difference in inflection, I rounded down your nuance to my preconceptions. As to novelty, I either did it great violence in deforming it into the mold of my own worldview, or felt visceral disgust at the intrusion of an alien thought.

You imagine that you would be distressed at this misunderstanding. Now imagine it playing out across society, in every relationship, over all scales. Then realize that this is not the worst of it.

You see, there is a peculiar subtlety to this mode of communication. If you happen to come across a grand piano, try this experiment. Weight the damper pedal, so that all the strings are free to vibrate. Attack and release a key, any number of keys: hear how they are sustained as though the initial attack were held. But attend more closely, and notice the reverberation beyond the sustained tones. Now manually but slowly depress a number of keys, such that the dampers rise but the hammers do not sound the strings. Attack and release other keys, while holding these first strings open: listen to the sounds sustained on the open strings. You should not be surprised to find that harmonic overtones are sustained, the fifths and octaves with their small-whole-number frequency ratios. But keep in mind that these are not the tones as they sound on the attacked strings, but as resonances of the open strings. Finally, weight the damper pedal again, carry an ordinary conversation, and listen to the piano sing back to you. What of your voice remains? Is it sustained, or subverted? Magnified, or mocked?

Evolution had equipped the individual with protection from positive feedback, in which the reverberation of one’s own voice stimulated the very nerves modulating the voice. (Some interesting disorders involved the failure of this mechanism. An afflicted individual might be unable to speak without risking what you would call migraines, or might sing continuously, or might echo or amplify any sound they heard.) But our friends’ acoustic forests were exquisitely sensitive. Even in the act of speaking, a speaker could detect the reverberation of its audience. And because the feedback-eliminating circuitry filtered out exact echoes of the spoken sound, that reverberation was heard as a caricature, emphasizing almost exclusively the absence of some of the original sounds and the presence of extraneous sounds where mismatched structures were partially excited. And recall, please, that here “sound” is essentially synonymous with “thought.”

Ah! But this, you say, this must be a silver lining. Any misunderstanding is immediately and automatically communicated, and can be corrected at leisure! And indeed in the tribal stages of civilization the difference was often appropriately diagnosed and common ground was found. Pair-bonded individuals, whose sense organs were induced to become more similar over time (and were generally quite similar to begin with), could close an especially harmonious aural loop. Deliberate invocation of a feedback cycle became a ritual as intimate as intercourse.

But the discourse of broader society admitted little harmony, and a speaker could not help but mishear the reverberation itself. The visceral distress at misunderstanding was amplified in the discordant echoes between interlocutors, in a positive feedback loop that Nature had not prepared them for. The voice determined personal enmity or friendship in a few words. Politics was quite literally sloganeering. The best, most sensitive minds confined themselves to painful solitude.

The ultimate futility of their discourse lay in the thin experience of the individual, both Echo and Narcissus. The scientific and philosophic faculties were circumscribed, never to lift a mind from squalor, and thus the story ends. For how can you understand the fullness of a Universe which speaks to you only in your own voice? Every telescope is a mirror. Awe becomes onanism. The gaze of man casts a light; the eye of man sees it. The hand of God moves the stars, and not a man heeds it.

The Ladder of Abstraction

Even with my relatively strict link curation, I’d have been comfortable linking pretty much any of Bret Victor’s talks or essays here. All in due time, I suppose. I’d call him an interaction designer, if I wanted to embarrass myself. He’s very and diversely competent, and he’s ambitious. His goals, in his own words: “Revolutionize how people learn, understand, and create. Give scientists the tools to diagnose and cure the world’s ills, and artists the tools to create and share beauty in ways currently impossible.” And that’s just in the short term. Someone to watch, at the very least.

Up and Down the Ladder of Abstraction: A Systematic Approach to Interactive Visualization looks kind of like it’s about the Manipulate[] function in Mathematica. It’s way more important, though. “To design” as the author uses it is arguably more “to think” than “to draw,” and “designer” is closer to “human” than to “one who professionally works with data visualizations.” (And the process he describes is especially important for scientists in both contexts.)

Book Review: How Learning Works

As promised, I review and point-by-point summarize How Learning Works: 7 Research-Based Principles for Smart Teaching by Susan A. Ambrose, Michael W. Bridges, Michele DiPietro, Marsha C. Lovett, and Marie K. Norman (2010), hereafter HLW as I scratch in futility at the sprawling length of this post. Cross-posted to Less Wrong.

Review

The authors aim to provide “a bridge between research and practice” for teaching and learning, very much in the spirit of Practical Advice Backed by Deep Theories. They concentrate on widely-supported results that are independent of subject matter and environment, so while the discussion is directed towards instructors in K-12 and college classrooms, there are also implications for essentially anyone in a teaching or learning role.

Let me restate that a little more strongly: any student, autodidact or not, would be well-served by internalizing the models and recommendations presented here. Teachers have even less of an excuse not to read the book, which is written very clearly and without sinking to punchy popularization. This is basic stuff, in the best possible way.

Sure, there are more sophisticated ideas out there; there exist subgenres of domain-specific research (especially for math and physics education); you can find diverse perspectives in homeschooling communities or in philosophy of education. There’s even some controversy in the depths of the research on some of the points in this book (though for the most part the scope of disagreements is still contained within the boundaries drawn by the authors). But as far as most people need concern themselves, HLW is an earnest and accurate if not quite comprehensive account of What We Know about learning.

[I do wish there were a similar account of And How We Think We Know It, looking into common research techniques, metrics of learning outcomes, systematic errors to guard against, reliability of longitudinal studies, statistics about replicability and retractions, and so on, but this isn’t it. The book lightly describes methods when it sees fit, and my scattered checks of unfamiliar studies leave me fairly confident that the research does in fact bear the claims the book makes.]

The book organizes research on teaching and learning into seven principles in order to “provide instructors with an understanding of student learning that can help them (a) see why certain teaching approaches are or are not supporting students ’ learning, (b) generate or refine teaching approaches and strategies that more effectively foster student learning in specific contexts, and (c) transfer and apply these principles to new courses.”

The principles are

  1. Students’ prior knowledge can help or hinder learning.
  2. How students organize knowledge influences how they learn and how they apply what they know.
  3. Students’ motivation determines, directs, and sustains what they do to learn.
  4. To develop mastery, students must acquire component skills, practice integrating them, and know when to apply what they have learned.
  5. Goal-directed practice coupled with targeted feedback enhances the quality of students’ learning.
  6. Students’ current level of development interacts with the social, emotional, and intellectual climate of the course to impact learning.
  7. To become self-directed learners, students must learn to monitor and adjust their approaches to learning.

Hopefully these ideas are not surprising to you. They are not meant to be; they stand mostly to organize diverse research findings into a coherent model (see principle #2). And if many of those research findings are old news to you as well, I also take that to be a point in favor of the book, and I trust that you will understand why.

Each chapter begins with two stories meant to illustrate the principle, a discussion of the principle itself, a discussion of the research related to that principle, and recommendations that take the principle into account. The chapters are interconnected but stand on their own. If you don’t plan to teach, you might get most of your value from Chapters 4, 5, and 7. There’s some fluff to the book, but not much. My summary, though long, leaves out the stories and examples, useful repetitions and rephrasings, detailed explanations, and specific recommendations, not to mention descriptions and citations of the relevant studies. I do not consider it a substitute for reading the book, which isn’t really that long to begin with.

Before I summarize HLW, I’ll make a couple brief comparisons. Why Don’t Students Like School: A Cognitive Scientist Answers Questions About How the Mind Works and What It Means for the Classroom by Daniel T. Willingham (2009) looks pretty similar, down to the format in which chapter titles ask questions which are then answered by Principles of Learning, followed by a discussion of the principle, followed by recommendations for the classroom. It’s written at a more popular level, with less discussion of actual research and lots more fluff. Only occasionally does it draw connections directly to a study, rather than use that as the chief mode of exposition (as in HLW). Each chapter does have a short annotated bibliography divided into less and more technical texts, which is nice. Willingham comes down strongly in favor of drilling and factual knowledge preceding skill. While that’s something I’ve approvingly polemicized about at some length, it needs a mountain of caveats. In general he optimizes (explicitly, in fact) for counterintuitive punchiness, and it’s not always clear how well-supported his advice really is. The organization and coverage feels haphazard to me, but where he hits on topics covered by HLW, he seems to agree.

The 25 Principles of Learning [pdf] from the University of Memphis learning group is a short document with a similar aim: a few sentences describing each principle, a couple sentences describing the implications, and a couple of references. It covers important points that HLW addresses only indirectly or that it inexplicably leaves out entirely (spaced repetition, testing, and generation effects, for example). It’s worth looking over to fill in those gaps. But it’s really “25 Important Findings on Learning”: it doesn’t give examples, offer very specific advice, or attempt to organize these principles into a causal model of learning. Consider them exercises for the reader.

Continue reading