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The Bicycle Problem: How the Illusion of Explanatory Depth Tricks Your Brain

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Do you know how a bicycle works? If asked, could you say where the chain, pedals and frame are? According to a 2006 study by the University of Liverpool, maybe not.

Participants in the study were asked to draw a picture of a bicycle. Later, to make sure that lack of artistic skill wasn’t a factor, they were asked to view pictures with different arrangements of chains, pedals and frames to state which corresponds to a working bicycle.

The result was that over 40% of participants couldn’t do it. Many participants drew bicycles that would be completely non-functional.

Many participants drew bicycles which were clearly non-functional

It’s amusing to think of what the person drawing these bicycles must have been thinking, such as locking the two wheels together via the frame so it can’t steer, or attaching both wheels to the chain. Before you get too smug, though, try testing yourself. Without looking, could you explain how a can-opener or a zipper works?

This bias—to believe we understand how familiar phenomena work far better than we actually do—is called the illusion of explanatory depth.

This type of overconfidence may be even worse for explanations than it is for remembering facts and trivia. Explanations often have different layers of depth. For instance, you may have correctly remembered that the chain of a bike attaches to the pedals and rear wheel, a relatively superficial explanation. But you may not know how the bike changes gears from the handlebars or how the brakes work, a deeper explanation.

This bias plagues students and knowledge workers, into thinking they understand things they don’t. Worse, the overconfidence sometimes causes people to blame the wrong problem when they can’t perform on tests or tasks.

Why Students (Incorrectly) Fault Memory When They Fail Tests

I get a ton of student emails, and one of the most frequent is a student blaming memory for poor test performance. A typical email would read something like this:

Hi Scott,



I struggle with remembering things for my tests. I understand everything in the class, but when the test comes around I seem to forget all of it. How can I memorize things better?

-Student

On one view, the student isn’t entirely wrong. Failure to produce information for a test can be seen as a failure of memory. But this is misleading, since after this diagnosis, the student decides that the best way to improve is to simply get better at memorizing all the information.

Unfortunately, many of these students are suffering under the same illusion as the participants in the bicycle experiment. They mistake their ability to recognize the logical operation of something with their ability to understand and explain it.

Few people would be baffled as to the function of a bicycle when they see one. For one, the object is too familiar to be surprising. Second, the operation seems readily transparent to inspection. You can push a pedal, see how the chain moves and how that rotates the back wheel.

But this ability to recognize and probe an object in front of you, is very different from the ability to correctly explain the object when it is out of sight.

The solution? Self-testing and tools like the Feynman Technique. Only by forcing yourself to explain does it become apparent how little you understand. Practicing explanations is also the key to form the kinds of memory you need to perform later.

Students suffer from this tendency very obviously, but I believe this also applies as a logical extension to many areas of knowledge work. Often the tendency is to believe because you’re familiar with something that you necessarily understand how it works. While that ignorance may not be a detraction for routine usage, it does impede creative solutions for novel problems.

My theory: good students (as well as programmers, designers, writers, etc.) cultivate a curiosity to test their own understanding of familiar things which combats the illusion of explanatory depth and builds expertise.

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nbouscal
1769 days ago
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Spokane, Washington
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What Can You Put in a Refrigerator?

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This may sound ridiculous, but I'm serious. The goal is to write a spec for what's allowed to be put into a refrigerator. I intentionally picked something that everyone has lots of experience with. Here's a first attempt:

Anything that (1) fits into a refrigerator and (2) is edible.

#1 is hard to argue with, and the broad stroke of #2 is sensible. Motorcycles and bags of cement are off the list. Hmmm...what about liquids? Can I pour a gallon of orange juice into the refrigerator? All right, time for version 2.0:

Anything that's edible and fits into a refrigerator. Liquids must be in containers.

Hey, what about salt? It fits, is edible, and isn't a liquid, so you're free to pour a container of salt into this fridge. You could say that salt is more of a seasoning than a food, in an attempt to disallow it, but I'll counter with uncooked rice. This could start a long discussion about what kinds of food actually need refrigeration--uncooked rice doesn't, but cooked rice does. Could we save energy in the long haul by blocking things that don't need to be kept cool? That word need complicates things, so let's drop this line of thinking for now.

Anything that's edible and fits into a refrigerator. Items normally stored in containers must be in containers.

How about a penguin? Probably need some kind of clause restricting living creatures. Maybe the edibility requirement covers this, except leopard seals and sea lions eat penguins. No living things across the board is safest way to plug this hole. Wait, do the bacteria in yogurt count as living? This entire edibility issue is troublesome. What about medicine that needs to be kept cool?

Oh no, we've only been thinking about residential uses! A laboratory refrigerator changes everything. Now we've got to consider organs and cultures and chemicals and is it okay to keep iced coffee in there with them. It also never occurred to me until right now that we can't even talk about any of this until we define exactly what the allowed temperature range of a refrigeration appliance is.

In the interest of time, I'll offer this for-experts-only spec for "What can you put in a refrigerator?":

Anything that fits into a refrigerator.

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nbouscal
1809 days ago
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Spokane, Washington
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What should a Bayesian infer from the Antikythera Mechanism?

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That is the early “computer,” remember?:

Who made the famed Antikythera Mechanism, the astronomical calculator that was raised from an ancient shipwreck near Crete in 1901?

The complex clocklike assembly of bronze gears and display dials predates other known examples of similar technology by more than 1,000 years. It accurately predicted lunar and solar eclipses, as well as solar, lunar and planetary positions.

For good measure, the mechanism also tracked the dates of the Olympic Games. Although it was not programmable in the modern sense, some have called it the first analog computer.

We now learn that the calendar of this mysterious device begins in 205 B.C.The key point, in my view, is that we have discovered no other comparable machine from antiquity or any other era other than modern times.  It took us until 2006 to even understand what the device was supposed to do, using advanced tomography, and we had been holding it since 1901.

So what to infer?  The first option is that this device was a true outlier, standing sui generis above its time.  Cardiff University professor Michael Edmunds “described the device as “just extraordinary, the only thing of its kind””.

As an artifact that is true, but is that so likely in terms of broader history?  It is pure luck that we fished this thing out of the Mediterranean in 1901.  (By the way, further dives are planned to search for more parts of it.)  The alternative possibility is that antiquity had many more such exotic devices, which have remained unreported, at least in the manuscripts which have come down to us.  That would imply, essentially, that we don’t have a very good idea of what antiquity was like.  In my view that is the more rational Bayesian conclusion.  It is more likely than thinking that we just lucked out to find this one unique, incredible device.  To put it another way, if you found some organic life on a traveling comet, you ought to conclude there is more of that life, or something related, somewhere else.

And to me, the Antikythera Mechanism does not to me sound like a “lone genius” kind of device: “The gear teeth were in the form of equilateral triangles with an average circular pitch of 1.6 mm, an average wheel thickness of 1.4 mm and an average air gap between gears of 1.2 mm.” (Wikipedia)  That suggests it was made by some kind of regular industrial process.  It also had some sophistications which modern Swiss watches do not.

Given this Bayesian conclusions, which other strange claims stand a decent chance of being true of antquity?  Which other surprises await us?

I find this an interesting passage: “the mysterious device was already pretty ancient by the time it went down some time around 85BC to 60BC with a ship carrying a bride and her dowry, io9 reports…”  You don’t find a lot of people carrying around a lot of ancient PCs today, so might there have been an Antikythera Great Stagnation way back when?  I think maybe so.

Here is a Lego model of the device.  Here is an introductory YouTube video.  Here is Wikipedia on the Antikythera Mechanism, a very good entry.

I owe thanks to Vic Sarjoo for pointers and Robin Hanson for a useful conversation on this topic.

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nbouscal
2157 days ago
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Spokane, Washington
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3 public comments
acdha
2155 days ago
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When in doubt, bet on people in the past being just as smart and motivated as we are today…
Washington, DC
dukeofwulf
2155 days ago
Counterpoint: Handwashing before surgery was ridiculed by medical authorities as recently as 1847. https://en.wikipedia.org/wiki/History_of_surgery#Antiseptic_surgery
acdha
2155 days ago
dukeofwulf: it's certainly not the case that there hasn't been considerable progress but even in that specific case, the use of antiseptic treatments (wine, vinegar, honey, etc.) or simple flushing to prevent infection was common at least as far back as the ancient Greeks and Chinese and e.g. Hippocrates advised sterilizing sutures according to http://afids.org/publications/PDF/CRI/Prevention%20and%20Management%20of%20CRI%20-4-%20-%20History.pdf. Even without germ theory, you can observe a lot of practical high-level outcomes – if not earlier, the Romans at least were both methodical enough and had no shortage of wounded soldiers for statistical studies. There was a neat Reddit AskHistorians thread awhile back: http://www.reddit.com/r/AskHistorians/comments/1tn59a/how_likely_was_a_roman_soldier_to_survive_being/
superiphi
2157 days ago
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We always seem to forget that people in antiquity had the same brains as we do. And many of them had plenty of time to use them as survival was taken care of
Idle, Bradford, United Kingdom
stefanetal
2157 days ago
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Some 'ancient' technology does seem puzzlingly sophisticated, outside of the lack of power technology and some metallurgy on par with 18th century technology. For instance Roman tunnel engineering.
Northern Virginia

Robert Pirsig

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"There is an evil tendency underlying all our technology - the tendency to do what is reasonable even when it isn't any good."
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nbouscal
2231 days ago
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Spokane, Washington
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4.5 Degrees

14 Comments and 45 Shares
The good news is that according to the latest IPCC report, if we enact aggressive emissions limits now, we could hold the warming to 2°C. That's only HALF an ice age unit, which is probably no big deal.
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nbouscal
2331 days ago
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Spokane, Washington
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14 public comments
sjk
2327 days ago
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So, if -1 IAU is a block of ice and 0 IAU is modern times, then +1 IAU is the world on fire. Clearly, the solution is to get a giant block of ice from Halley's Comet every so often. That will solve "Global Warming"™© once and for all. Or maybe we need to resurrect "Global Cooling" and "Nuclear Winter" from the 1970s. That will even things out.
Florida
Satri
2331 days ago
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Are we ready?
Montreal, Canada
zippy72
2331 days ago
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Eeeeeeeekkkkkkk!
FourSquare, qv
Michdevilish
2331 days ago
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The degrees of change
Canada
emdeesee
2331 days ago
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Let's just get a little perspective, shall we?
Sherman, TX
glindsey1979
2331 days ago
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Once again, XKCD hits the mark perfectly.
Aurora, IL
stefanetal
2331 days ago
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That's 1 IAU within 100 years. Temperature increases keep going after that...there's lots of interia in the system just from simple things like the large specific heat of water in the oceans.
Northern Virginia
sommerfeld
2331 days ago
Note that the impact of CO2 concetration on warming is logarithmic. the key parameter is "climate sensitivity": how many degrees C warming you get per *doubling* in CO2 concentration.
toddmichaelryan
2331 days ago
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Love it
JayM
2331 days ago
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.
Atlanta, GA
RogerShepherd
2331 days ago
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XKCD's call on global warming
Bristol, UK
michaelglass
2332 days ago
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Yup. I'm sharing xkcd.
San Francisco
aaronwe
2332 days ago
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Well there's some terrifying perspective.
Denver
istoner
2332 days ago
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Gulp.
Saint Paul, MN, USA
DrGaellon
2332 days ago
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Alt text: "The good news is that according to the latest IPCC report, if we enact aggressive emissions limits now, we could hold the warming to 2°C. That's only HALF an ice age unit, which is probably no big deal."
Yonkers, NY

Free Speech

21 Comments and 73 Shares
I can't remember where I heard this, but someone once said that defending a position by citing free speech is sort of the ultimate concession; you're saying that the most compelling thing you can say for your position is that it's not literally illegal to express.
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nbouscal
2383 days ago
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Spokane, Washington
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20 public comments
pavlov02
2372 days ago
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Just seems like common sense to me but that seems in short supply.
merlinblack
2376 days ago
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Not applicable in Canada but a good lesson I'm discourse.
ÜT: 53.542319,-113.494597
Romanikque
2376 days ago
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Alt text is better than the comic for this one...
Baltimore, MD
tewhalen
2383 days ago
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Wikipedia: "The Citizens' Councils used economic tactics against African Americans whom they considered as supportive of desegregation and voting rights, or for belonging to the NAACP; the tactics included 'calling in' their mortgages, denying loans and business credit, and boycotting black-owned businesses. In some cities, the Councils published lists of names of NAACP supporters and signers of anti-segregation petitions in local newspapers in order to encourage economic retaliation. For instance, in Yazoo City, Mississippi in 1955, the Citizens' Council arranged for the names of 53 signers of a petition for school integration to appear in a local paper. Soon afterward, the petitioners lost their jobs and had their credit cut off." -- Apparently, no free speech rights were violated.
chicago, il
grammargirl
2383 days ago
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Yup.
Brooklyn, NY
stefanetal
2383 days ago
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This strikes me as an 'argument from definition'. But the definition itself is contested. Lot of rights don't work this way, for instance there are non-retaliation laws asociated with many rights (especially in labor law -- say the right to marry includes the right, for the most part, not to get fired for getting married).
Northern Virginia
tewhalen
2383 days ago
Like, remember this comic when your supervisor shows up to your cubicle and asks you to donate to the "Conservative Victory Fund PAC" or lose your job. At least you'll have the comfort of knowing your free speech rights weren't violated.
chrisamico
2383 days ago
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I'd love to post this at the end of every news site's comments policy.
Boston, MA
diannemharris
2383 days ago
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I have to save this for future postings, everywhere
satadru
2383 days ago
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It's dawning on me that wikipedia needs Tl;DR links pointing to the relevant xkcd pages.
New York, NY
ChrisDL
2383 days ago
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You haven't lived until you've shared an XKCD online
New York
sfringer
2383 days ago
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Couldn't be better stated on free speech...
North Carolina USA
neilcar
2383 days ago
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Eventually, XKCD will be the answer for every ridiculous argument.
Charlotte, North Carolina
karmakaze
2383 days ago
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Alt text: I can't remember where I heard this, but someone once said that defending a position by citing free speech is sort of the ultimate concession; you're saying that the most compelling thing you can say for your position is that it's not literally illegal to express.
07974
darastar
2383 days ago
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THIS X1000
ktgeek
2383 days ago
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Yet another xkcd that will be reposted and reposted until the sun burns out.
Bartlett, IL
Michdevilish
2383 days ago
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Free to leave
Canada
JayM
2383 days ago
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.
Atlanta, GA
Askew
2383 days ago
...
aaronwe
2383 days ago
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There should be a "BUT FREE SPEECH!" corollary to Godwin's Law.
Denver
mindspillage
2383 days ago
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This was basically designed to be passive-aggressively linked to in mailing lists/forums/IRC...
north bay, California
stavrosg
2383 days ago
I can't count how many times this would have been useful in the past...
sulrich
2375 days ago
and for that reason it's getting an expansion snippet.
jtgrimes
2384 days ago
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Alt text: I can't remember where I heard this, but someone once said that defending a position by citing free speech is sort of the ultimate concession; you're saying that the most compelling thing you can say for your position is that it's not literally illegal to express.
Oakland, CA
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