"...far too low an estimate."
February 4, 2012 10:32 AM   Subscribe

10 Misconceptions Rundown is an entertaining, fast-paced debunking of a number of commonly held beliefs. [SLYT]
posted by quin (82 comments total) 17 users marked this as a favorite

 
Regarding eight glasses of water per day, many years ago my statistics professor told the class how he was working with one of the major manufacturers of bottled water and how it was utterly pointless in consuming additional water beyond meals and when you're thirsty. He also added that it could be bad for your health as excessive water drinking causes incontinence when you get older. This during a lecture where half the class were clutching to a water bottle as if their lives depended on it.
posted by Foci for Analysis at 10:48 AM on February 4, 2012


I did not need to hear the bit about spiders.
posted by calamari kid at 10:49 AM on February 4, 2012 [4 favorites]


I feel like I could have made this video. That probably makes me a bit of a jerk.

I bet a lot of folks here have never heard of the fan thing before. It's pretty weird; but then, people/culture believe a lot of weird things that are false.

I'm surprised he didn't include the "glass flows in old windows' one, I would have.
posted by Ivan Fyodorovich at 10:50 AM on February 4, 2012


Great ending.
posted by NoMich at 10:51 AM on February 4, 2012


"Regarding eight glasses of water per day, many years ago my statistics professor told the class how he was working with one of the major manufacturers of bottled water and how it was utterly pointless in consuming additional water beyond meals and when you're thirsty. He also added that it could be bad for your health as excessive water drinking causes incontinence when you get older. This during a lecture where half the class were clutching to a water bottle as if their lives depended on it."

I was just arguing about this one with my mom, an RN, the other day. RNs, especially, are deeply fond of the "drink lots of water" thing. But it's not supported by any real science and, these days, most nutritionists know it's not true. It's also not true that caffeine drinks like coffee and soft-drinks are dehydrating—for someone unaccustomed to them, they can be initially, but the body soon adjusts. There's some interesting sociology in tracing the people need to drink much more water meme since it began.

Another one that occurs to me is the belief about "catching cold". I suppose that most people now understand how the rhinoviruses are transmitted and that any correlation to cold weather is, well, a correlation and not a causation. And is suspect and, if it exists, is loose. But it's still extremely common.

Yeah, I could make about five of these videos. Because I am annoying.
posted by Ivan Fyodorovich at 10:57 AM on February 4, 2012 [3 favorites]


I've been enjoying some of the other videos by this producer. This followup to the one in the fpp includes a shout out to Metafilter.
posted by not_that_epiphanius at 11:06 AM on February 4, 2012 [1 favorite]


Anyone got a similar video debunking conspiracy theory madness?
posted by Dodecadermaldenticles at 11:10 AM on February 4, 2012


Ivan Fyodorovich, do you know where to find good information on the dehydrating effects of coffee/soft drinks? I've gotten into that argument a few times and I'd like something to point to.

The "catching cold" phenomenon bears out anecdotally, which I'd suspect is the result of the body allocating energy into keeping up your body temperature at the expense of other things like immune defense, with viruses being pretty ubiquitous.
posted by EtzHadaat at 11:16 AM on February 4, 2012 [1 favorite]


I still believed 3! Oh dear.

As for 8, regarding your brain, saying "all the bits matter" is probably too strong. Though I recognize that the 10% stat is wrong, you can lose a fair chunk of your brain and keep functioning pretty well. It's obviously more complex.
posted by Jehan at 11:26 AM on February 4, 2012 [1 favorite]


Just wondering, not having seen the video yet, but generally speaking, do some of the "debunkings" not also fall into the freakanomics method of sometimes poorly proven contrarianism? Not saying, just asking.
posted by blue shadows at 11:27 AM on February 4, 2012 [1 favorite]


I want to see an informed opinion on the 'five a day' mantra. It was invented by a PR company. It must be a myth.
posted by Summer at 11:34 AM on February 4, 2012


People actually believe that blood in veins is blue? Good god. What educationally-benighted part of the world does that happen in? Indiana? And yes, people who buy bottled water are mugs.
posted by Decani at 11:36 AM on February 4, 2012


LOL +1 if you noticed that the map zoom-in on South Korea included a Starcraft Command Center, Nexus, and Hatchery.
posted by Salvor Hardin at 11:38 AM on February 4, 2012 [6 favorites]


As for 8, regarding your brain, saying "all the bits matter" is probably too strong. Though I recognize that the 10% stat is wrong, you can lose a fair chunk of your brain and keep functioning pretty well.

Acute brain lesions on the other hand can cause debilitating disorders like blindness in one half of one's field of view (not just one eye) or the inability to naturally detect motion (despite understanding that something's position seems to keep jumping). And these things are relatively impossible to recover from - they can only be adapted to.

Kids can recover from things like having a hemisphere removed, but that doesn't mean it isn't useful. Bigger brains has tended to mean bigger performance. The difference between a 1.5 and 3.0 Gigahertz chip is both not a lot and a lot. Depending on what you want to do.

And this may be simply another myth, but I always figured where the 10% myth came from was that at any particular time, only a relatively small proportion of our brain is actually in use. The whole thing isn't exactly storming away all the time.
posted by Alex404 at 11:39 AM on February 4, 2012


The "catching cold" phenomenon bears out anecdotally

When it's cold outside, you're most likely to spend time indoors with others, giving bacteria and viruses plenty of vectors to infect.

RNs, especially, are deeply fond of the "drink lots of water" thing. But it's not supported by any real science and, these days, most nutritionists know it's not true.

Certainly we need a certain amount of water every day, but what most people forget is that we get an awful lot of our water from food. Though it might not be obvious at first, most kinds of food are loaded with moisture, and our bodies are keen to make use of it. "8 glasses a day" was a completely arbitrary figure that appeared in some old nutrition book in the early 20th century and somehow managed to get repeated enough that it's now taken as canon law.
posted by ShutterBun at 11:40 AM on February 4, 2012


Also: good use of the 7 legged spider drawing in the video.
posted by ShutterBun at 11:40 AM on February 4, 2012 [3 favorites]


Am I the only one that saw the word "rundown" and thought Scientology?
posted by xil at 11:42 AM on February 4, 2012 [2 favorites]


which I'd suspect is the result of the body allocating energy into keeping up your body temperature at the expense of other things like immune defense, with viruses being pretty ubiquitous.

Or it could just be the various live virus in the nose getting their chance.

Getting chilly can bring on a cold. Researchers at Cardiff University's Common Cold Center paid 90 students to sit for 20 minutes with their bare feet in buckets of cold water. A few days later the study found that 13 of the students reported cold symptoms, such as a runny nose or sore throat, compared to five in a control group of 90 students who kept their feet dry in socks and shoes. When feet are placed in cold water, there is constriction to the blood vessels in the nose. This may be one of the factors that actually can aid the virus by lowering the defences within the nose and triggering the symptomatic infection. Previous studies inoculated patients with the cold virus and then chilled them, but failed to find any link between temperature and catching a cold.
posted by rough ashlar at 11:44 AM on February 4, 2012 [3 favorites]


I'm surprised he didn't include the "glass flows in old windows' one, I would have.

Dear god...I'm having alt.folklore.urban flashbacks. Flowbies!
posted by ShutterBun at 11:44 AM on February 4, 2012 [1 favorite]


And then there's this AskMe from Griphus about misconceptions about health.
posted by runningwithscissors at 11:45 AM on February 4, 2012


When it's cold outside, you're most likely to spend time indoors with others, giving bacteria and viruses plenty of vectors to infect.

And less exposure to UV light taking the fat in your skin and making "Vitamin" D.

An hour long audio with ads
posted by rough ashlar at 11:47 AM on February 4, 2012


the cold virus

Hehe. "The."

By the way, rough ashlar, that same article seems to be recommending zinc lozenges as a remedy. More misinformation, please!
posted by ShutterBun at 11:48 AM on February 4, 2012


Acute brain lesions on the other hand can cause debilitating disorders like blindness in one half of one's field of view (not just one eye) or the inability to naturally detect motion (despite understanding that something's position seems to keep jumping). And these things are relatively impossible to recover from - they can only be adapted to.

Kids can recover from things like having a hemisphere removed, but that doesn't mean it isn't useful. Bigger brains has tended to mean bigger performance. The difference between a 1.5 and 3.0 Gigahertz chip is both not a lot and a lot. Depending on what you want to do.


Sure, that's why I recognized that it's complex. But "every bit matters" is just another misconception as it is too strong and without the exceptions regarding the possibility of recovery from brain trauma. I know it's too short a video to explain everything, but a different choice of words would have been clearer. Lose part of brain = lose part of function just isn't strictly true.
posted by Jehan at 11:51 AM on February 4, 2012


I would love to kill that "only manmade thing visible from space" meme dead with a fire so large and intense it's visible from space. Seemingly every other green campaigner likes to talk about how only the tarsands mining operations or decapitated Appalachian mountaintops or Gulf of Mexico oil slicks or their own outsized bleeding heart is visible from space. This is always delivered in a tone of gravity reserved for cancer diagnoses and news that the asteroid's on an unstoppable collision course with the town you call home.

Maybe all of them are visible space. Maybe just some. But so's every city of a million-plus illuminated against the night, and yet few of us would advocate against artificial light. (Yes, yes, I know about the Dark Skies movement. Fine, yes, I'll take a goddamn pamphlet . . .)

In any case, it's simply not nearly as outrageously compelling a piece of unvarifiable anecdata as you think it is, and you should erase it from your fevered mind, alright?
posted by gompa at 11:53 AM on February 4, 2012 [1 favorite]


I just googled "five a day". This was the result:

five a day = 5.78703704 × 10-5 hertz
posted by symbioid at 12:01 PM on February 4, 2012 [6 favorites]


I feel so uninformed! I never heard of the "glass flowing" myth and had to Google it.
posted by Cranberry at 12:02 PM on February 4, 2012


Regarding the follow-up video, wherein our intrepid debunker kinda calls out snopes and questions their methods, I can assure you all that if they say it appeared in "PC Professional" magazine, it surely did. David and Barbara's house is packed to the rafters with magazines and newspapers, so it's not surprising that their collection of periodicals includes titles unknown to the Library of Congress. (I worked with David and Barbara on a few television appearances and we were pretty close friends once upon a time)
posted by ShutterBun at 12:02 PM on February 4, 2012 [2 favorites]


The "catching cold" phenomenon bears out anecdotally, which I'd suspect is the result of the body allocating energy into keeping up your body temperature at the expense of other things like immune defense, with viruses being pretty ubiquitous.

I've recently heard that the virus remains viable longer outside the host at cooler temperatures.
posted by StickyCarpet at 12:07 PM on February 4, 2012


The spider thing seems to be a quote from this comic.
posted by martinrebas at 12:19 PM on February 4, 2012 [2 favorites]


The 8 glasses of water a day myth annoys me beyond all reasonable levels. I don't know why. But it makes me want to punch someone.
posted by Justinian at 12:26 PM on February 4, 2012 [2 favorites]


Big CGP Grey post previously
posted by Blasdelb at 12:36 PM on February 4, 2012


Yeah, some of us have been told by urologists to drink more water after epic bouts of kidney stones (why yes, lying on the bathroom floor wanting to die was a low point of my life, thanks), but for most folks 8 glasses of water just means 8 more trips to the bathroom.
posted by Lentrohamsanin at 12:37 PM on February 4, 2012 [2 favorites]


The mayo clinic guidelines for water go higher than 8 cups. The Institute of Medicine determined that an adequate intake (AI) for men is roughly 3 liters (about 13 cups) of total beverages a day. The AI for women is 2.2 liters (about 9 cups) of total beverages a day.

Conditions may vary, but it helps to remember that long term dehydration is responsible for tooth decay, bad breath, constipation, brain shrinkage, and probably jock itch and religious fundamentalism.
posted by Brian B. at 12:44 PM on February 4, 2012 [5 favorites]


I always assumed that the 10% of your brain thing didn't refer to actual brain mass, more like cognitive ability. For example I may use 100% of the muscles in my arm lifting this doughnut to my mouth, but I'm capable of doing so much more. And with enough adrenalin in a short burst, there'a a whole other level of strength that may go beyond what you could do in a gym under normal circumstances. Based on my observations i'd feel safe in saying that most people are cognitively capable of more than they do on a day to day basis.

Of course, I also assumed the 10% number was hooey, because how can you measure such a thing? It is also true that our brains are doing a lot of behind the scenes work that we are mostly unaware of, what with keeping the Matrix updated and all that. And anyone who's ever experimented with psychedelics can probably attest to the brain being capable of all sorts of tomfoolery that's probably best kept under wraps 90% of the time.
posted by billyfleetwood at 12:51 PM on February 4, 2012 [1 favorite]


11) There's an invisible man in the sky that watches you masturbate.
posted by Brocktoon at 12:54 PM on February 4, 2012 [5 favorites]


In the sky, hell -- the bastard is right here in the room with me!
posted by Guy_Inamonkeysuit at 2:16 PM on February 4, 2012


Yeah, but the point is that most people get those fluids in the food they consume; drinking 8+ cups of water on top is unnecessary
posted by Justinian at 2:39 PM on February 4, 2012


Fan Death was kind of stupid inclusion since it is a really localized thing in Korea and everyone outside that country knows that is cuckoo. That is aside from some of the Koreans living in other countries.

One I've never seen people talk about is the maximum heart rate equation. XXX - your age = max rate. It was an equation a doctor came up with as a safe guide to put his subjects through tests. He never meant it as a rule of thumb for everyone to latch onto and use. People can and do exercise past their max heart rates all the time with no resulting problems.

But "every bit matters" is just another misconception as it is too strong and without the exceptions regarding the possibility of recovery from brain trauma.

This is kind of weird roundabout way to talk about the 10% idea, but I wouldn't bet money that there are useless bits that can be lopped off without any repercussion. It doesn't take much damage at all to seriously mess up your brain. I mean unless you're saying "functioning" is tantamount to "no visible signs of distress and went right back to living the same life in the same way" I think you're making making a hefty argument. Otoh, if you're idea of regaining "functioning" is "he can still get his own food, but needs a bib, and tie his shoes, but can't find them most of the time" falls within normal range, then you may have a point. I'm not disregarding the neuro-plasticity of the brain, but I don't think there is an unused portion of the brain that can be lost without something happening.

Caffeine not being a diuretic is news though. I would be curious if they did the studies with non-coffee-drinkers. I stay away from caffeine and if I have a cup of coffee I start peeing like crazy. I wouldn't say I get dehydrated, and I'm sure I would acclimate to it's diuretic affects if I drank it often enough.
posted by P.o.B. at 2:44 PM on February 4, 2012


Yeah, but the point is that most people get those fluids in the food they consume; drinking 8+ cups of water on top is unnecessary

I think the "myth" video is opinionated, and the fallacious spider comment without any evidence gave it away. Emergency rooms aren't filled with oral spider bites, despite them liking warm moist places.

Anyway, since water intake is an important topic due to the billions spent on problems related to dry mouth, dry skin, dry hair and dry eyes, and all those digestive aid products, (not to mention the harmful liquid substitutes people grab when they are thirsty) here's the results from two other sites:

Water intake calculator. Here, I filled out an average scenario for instant viewing. Bottom line: If you eat a healthy diet, about 20 percent of your water may come from the foods you eat. If you eat a healthy diet you can drink 107.6 ounces of water today, or 3.2 liters.

Can you drink too much water? Bottom line: The kidneys of a healthy adult can process fifteen liters of water a day! You are unlikely to suffer from water intoxication, even if you drink a lot of water, as long as you drink over time as opposed to intaking an enormous volume at one time. As a general guideline, most adults need about three quarts of fluid each day. Much of that water comes from food, so 8-12 eight ounce glasses a day is a common recommended intake. You may need more water if the weather is very warm or very dry, if you are exercising, or if you are taking certain medications. The bottom line is this: it's possible to drink too much water, but unless you are running a marathon or an infant, water intoxication is a very uncommon condition.
posted by Brian B. at 3:08 PM on February 4, 2012


I always figured where the 10% myth

I always heard that as use consciously, which makes more sense to me, seeing as how much we don't really control. Sort of like if you had 100% you could control your heart rate, sweating, glands, etc. Basically everything the brain controls, along with optical illusions and such. Not sure when it just became "use 10%", but if you've known it the other way, it's an of course thought. Heck, even our memory which we "use" gets messed about with our subconscious.


The spider thing is odd, where are you that you have that many spiders? ;) I've woken up once with a fly in my mouth, that freaked me out big time, and a fly in my ear, and that one sucked. Took forever to get out too, hearing it, feeling it. Ugh. (Sorry for the derail)
posted by usagizero at 3:34 PM on February 4, 2012


Fan Death was kind of stupid inclusion since it is a really localized thing in Korea and everyone outside that country knows that is cuckoo.

Oddly, I'd always heard of it as localized to some parts of India, not SK— but I've read one person saying it was a Well Known Fact in their family in the American South. (Maybe someone's grandmother was from India or Korea, though.) I've always wondered how this belief came about. One theory is: smoldering fire in sealed room → death; electrical appliances are kind of like fires; therefore fans in a sealed room → death. But if that's how it came about then you'd expect similar fears about electric space heaters and nightlights.

Re 10%-of-the-brain, I've read of people who had extremely little brain matter and yet were intellectually normal. (Much to their doctors' or autopsier's surprise.) IIRC there are two famous cases of this in the medical literature. OTOH, I think everyone suspects that the reports are mistakes somehow. Anyway, assuming the reports are accurate, it might be correct to rephrase that one as "it's possible to do everything you're doing with only 10% (or 20%) of the brain you have (so just imagine how smart you'd be if you used it more effectively, or whatever motivational point the speaker is trying to make)". Of course, even so, most people with only 10% of a normal brain are vegetables or dead, so I'm not sure how motivational this factoid would really be…
posted by hattifattener at 3:59 PM on February 4, 2012


The spider "fact" was allegedly created by a magazine columnist as a way to demonstrate how easily these erroneous facts can spread. However, it seems that the columnist and the magazine she wrote for may have never existed.

A mystery!
posted by halftone at 4:20 PM on February 4, 2012 [1 favorite]


He had me at name-checking Plavalaguna.
posted by sonascope at 4:21 PM on February 4, 2012 [1 favorite]


Oh, and here's a follow-up video, addressing the mystery surrounding the spider myth.
posted by halftone at 4:25 PM on February 4, 2012


Fun!
posted by tumid dahlia at 4:34 PM on February 4, 2012


I'm almost certain the spider-eating idea is a lot older than 1993, and that's from fading memory. I would guess 1953 if I had to bet money on it, and I wasn't even alive then. People have been making useless lists of facts for as long as they've been publishing useless filler articles in magazines and newspapers. Every wrong fact I've ever encountered on the internet came from people who recall these errors from the days when nothing could be verified. That goes for most of that pseudo-inspirational spam coming from all those trailer churches in Texas too. (Why anti-virus companies don't filter them is beyond me).
posted by Brian B. at 5:31 PM on February 4, 2012


This is kind of weird roundabout way to talk about the 10% idea, but I wouldn't bet money that there are useless bits that can be lopped off without any repercussion. It doesn't take much damage at all to seriously mess up your brain. I mean unless you're saying "functioning" is tantamount to "no visible signs of distress and went right back to living the same life in the same way" I think you're making making a hefty argument. Otoh, if you're idea of regaining "functioning" is "he can still get his own food, but needs a bib, and tie his shoes, but can't find them most of the time" falls within normal range, then you may have a point. I'm not disregarding the neuro-plasticity of the brain, but I don't think there is an unused portion of the brain that can be lost without something happening.

Thinking it through some more, my objection isn't necessarily relevant to the message of the video. "Every bit matters" should be construed just as "we use it all" in opposition to the 10% myth. It doesn't necessarily mean that having less than 100% is incompatible with being a functioning human, in the sense that damage or loss always results in a clearly compromised existence. That would likewise be a misconception, even though it is closer to the reality.
posted by Jehan at 5:46 PM on February 4, 2012


If you eat a healthy diet, about 20 percent of your water may come from the foods you eat. If you eat a healthy diet you can drink 107.6 ounces of water today, or 3.2 liters

You can. But you'll be pissing like a racehorse. Unless you are feeling unwell, drinking as much as you like is the answer. We already have an excellent physiological protection against dehydration, known as "feeling thirsty". The idea that one can only derive 20% of required water from food is bunk, and obviously so, as food and water mix to a delicious slurry in the stomach and intestine. Most people need between 2 and 3 litres a day in total, depending on any number of factors. Thankfully, as any healthy person will feel thirsty long before they're dehydrated, we can all stop worrying about it and move on.
posted by howfar at 7:00 PM on February 4, 2012


I've always been amused and slightly annoyed by the advice that "by the time you're thirsty it's already too late – dehydration has set in." What a crappy bodily mechanism we have. Besides – "it's too late?" Should I just wait around to die?
posted by argybarg at 7:12 PM on February 4, 2012 [5 favorites]


We already have an excellent physiological protection against dehydration, known as "feeling thirsty". The idea that one can only derive 20% of required water from food is bunk, and obviously so, as food and water mix to a delicious slurry in the stomach and intestine. Most people need between 2 and 3 litres a day in total, depending on any number of factors. Thankfully, as any healthy person will feel thirsty long before they're dehydrated, we can all stop worrying about it and move on.

The idea we "have" something prehistoric that modernly protects us at all times is a comforting denial. We also over eat much different foods than before, so much for that mechanism that would cut off the danger of eating too much. We also eat a lot of salt and sugar now, for example, and thirst can't be assumed to be always reliable as an evolutionary mechanism if we evolved differently than our modern food chain would suggest. Also, many think that thirst is mistaken for hunger. It could be that overeating destroys our thirst response but leaves us dehydrated from salt. I don't think we can assume anything but symptoms of dryness.
posted by Brian B. at 7:26 PM on February 4, 2012 [4 favorites]


Regarding eight glasses of water per day, many years ago my statistics professor...

Oh, well then - I'll just disregard the stern admonitions of those urologists that I drink at least two liters of water a day, because a statistics professor thinks they're wrong. And because any healthy person feels thirsty before they're dehydrated, according to Doctor howfar, I can likewise disregard those urologist's advice to monitor the color of my urine. If I'm not thirsty, it can't matter when it's dark yellow, so I can stop worrying about it.

As for all consumers of bottled water being "mugs," let's remember that not everyone lives where the water supply is tasty or in some cases even safe to drink.
posted by Kirth Gerson at 7:34 PM on February 4, 2012 [4 favorites]


The 8 glasses a day thing always bugged me because I could never find out just how much a "glass" is. I never heard the statistic in "cups" or anything else -- just glasses. As a child, I felt betrayed and dubious about a science community that would leave such an important term undefined.

Having watched the spiders follow-up... I'm now really curious.
posted by meese at 8:58 PM on February 4, 2012


Lose part of brain = lose part of function just isn't strictly true.

Maybe not, but I do suspect that it all matters, to some degree. After all, the human brain has very high metabolic requirements, and is part of why pregnancy tends to be more traumatic for human females than other mammals. With those kinds of evolutionary burdens, I have to assume that every ounce buys us something.
posted by Edgewise at 9:12 PM on February 4, 2012


You may only use the brakes on your car 10% of the time, but you damn well notice when they're gone.
posted by Jilder at 9:21 PM on February 4, 2012


The brain thing:
I first heard it as, "You only think with 30% of your brain." That's probably a lot closer to true. The cerebral cortex is only a few milleters thick, and probably doesn't even make up 30%, although I suppose it may.
But it irritated me that 30% drifted to 10%, and that "think with" became "use", which is not the same at all. There are plenty of parts of our brains that we use for stuff other than thinking, but lots of people seem to not know that.
posted by Mister Moofoo at 10:16 PM on February 4, 2012


IIRC there are two famous cases of this in the medical literature.

I would be curious what those were. I know people like to talk about the guy who had the rail spike go through his forebrain and basically walked away from it. Although he was perfectly functional, he definitely did not function the same afterwards. According to reports he was emotionally erratic, which makes sense given the area that was damaged.

I first heard it as, "You only think with 30% of your brain."

The area of higher functioning does make up a significant portion, but I'm pretty sure there's more to processing thoughts than just that area and I don't think you can quite divorce the sections from each other like that.
posted by P.o.B. at 10:25 PM on February 4, 2012


"Caffeine not being a diuretic is news though. I would be curious if they did the studies with non-coffee-drinkers. I stay away from caffeine and if I have a cup of coffee I start peeing like crazy. I wouldn't say I get dehydrated, and I'm sure I would acclimate to it's diuretic affects if I drank it often enough."

Caffeine is a diuretic. But it's one that the body acclimatizes to relatively quickly and so for those who regularly drink caffeinated beverages, it's not dehydrating. Note that the myth is that it's dehydrating—that is, you lose more water than you ingest. Which means that the caffeine would have to not only be a diuretic, but to be strong enough to induce the loss of more water than was consumed in the caffeinated drink.

It's been a long while since I read about this, but I'm pretty sure that it's not the case that people who regularly consume caffeine become completely inured to its diuretic effects, but that it lessens quite a bit and thus the difference between drinking a soda or cup of coffee and a cup of water just isn't very much.

With regard to Brian B and others who have urologists recommending that they drink a lot of water; well, there's drinking water to avoid dehydration and drinking water to reduce the formation of kidney stones. Those are two distinct things. If you've got a kidney stone problem, the more water you drink the better, because the most water going through your kidneys, the more dilute the minerals are and the less the formation of the stones. You're not doing it because you are dehydrated.

But, also, doctors are not much more immune to folk wisdom about health than other people. Well, "not much more" is an overstatement, but physicians in general and within specialties have their own folk wisdom that they cling to regardless of research or even what they were taught in med school. There's quite a bit of institutional wisdom about treatment passed along informally, and it's not all supported by science. Doctors are people, too, and medicine's far from an exact and rigorous science. Also, nutrition is an especially volatile and uncertain area. That both calls into question the science and encourages practitioners to be conservative in favoring older, received wisdom. That's what's happening with the water thing among the nursing community. Making sure patients are sufficiently hydrated is such a key part of hospital nursing care, and therefore also nursing care in general, that it looms very large in nursing lore.
posted by Ivan Fyodorovich at 12:05 AM on February 5, 2012


I found a brief abstract that includes some of the potential benefits of hydration in treating disease. There's also this about heart disease and hydration. What also might help to consider is the fact that people drink large amounts of fluid on a daily basis, but less so water. Drinking more water would probably replace many of the others through lowering the thirst that drives people to drink soda or beer. I suppose this alone would source fund the water naysayers for generations.
posted by Brian B. at 1:07 AM on February 5, 2012


"I suppose this alone would source fund the water naysayers for generations."

Ah. Well, your fervency about this issue signals to me that this is perhaps more of a moral matter to you than science. That's an aspect I didn't really consider, but is definitely in play—the whole puritanical "body is a temple" thing where drinking water rather than other things, and in general drinking lots of water because it's pure and natural and whatnot, is a moral act.

I don't use the word "puritanical" lightly. Americans have a very strong cultural instinct toward puritanism. Across the political spectrum it manifests in many different ways. One of those involves diet. And diet also involves disgust instincts, so I think it can easily be linked to subconscious notions of shame and shaming. All this is to say that I think a lot of people have large investments in supporting the "eight glasses of water a day" thing because, basically, it strikes a virtuous note at some deep level.

I'm not sure how serious and likely are the risks of excessive hydration. At the lower levels that are more realistic, it probably just involves lowering some electrolytes and such and could easily be countered. The more serious version, which has to do with osmotic stuff, takes a relatively huge amount of excessive hydration and I can't imagine it's really much of a concern.

So, really, for most people the only downside to drinking eight glasses of water a day is having to pee more often. You're probably not getting a health benefit from it, unless you have a particular condition (like a propensity for kidney stones), but if it makes you feel better about yourself and the world, enjoy it. No harm done.

Well, okay, excepting with bottled water, which is an actual waste of resources that has definite social harm. On the other hand, as consumption goes in the context of Americans, it's just a tiny drop in the bucket.
posted by Ivan Fyodorovich at 1:27 AM on February 5, 2012 [2 favorites]


Ah. Well, your fervency about this issue signals to me that this is perhaps more of a moral matter to you than science.

I thought your first post was really bad, and now this one.
posted by Brian B. at 1:30 AM on February 5, 2012


I always assumed that the one reason for "catching cold" is that in winter, the lining of the nose and throat can be damaged by cold, dry air, making it easier for viruses to enter the body.
posted by KokuRyu at 1:43 AM on February 5, 2012 [1 favorite]


"I thought your first post was really bad, and now this one."

This really isn't controversial. Unless someone has a medical condition that requires it, people don't need to drink eight glasses of water a day. Most people aren't chronically dehydrated, full stop.

"I always assumed that the one reason for 'catching cold' is that in winter, the lining of the nose and throat can be damaged by cold, dry air, making it easier for viruses to enter the body."

Per some of the discussion above, there may well be some things associated with cold weather that make it more likely for the rhinoviruses to run rampant in an individual person. However, it seems to me that the epidemiological factors are sufficiently explanatory for the existence of this folklore. Note also that cold dry air all by itself makes one's nose run, and even the eyes to water. For everyone who saw Contagion the statistic about how often people touch their faces is very memorable. Cold weather causes a lot of behavioral changes in people, individually and in groups, and it really doesn't take very much, epidemiologically, for those changes to cause large effects.

You know, it occurs to me that many people may not be aware that the science of the common cold has really improved during our lifetimes. While the rhinovirus was first recognized in the 50s, I recall that even through the 70s and 80s there was still uncertainty (or controversy) about the cause of the common cold. Now, though, there's no doubt that the common cold results from the rhinoviruses, and we know that they mutate rapidly and there are many, many variants extant.

I may be wrong about this, but I'm pretty sure that most everyone is infected to some degree by some rhinoviruses. It's more about how well the immune system is keeping them in check in conjunction with new infections and new variants.

Like Shutterbun, I'm an old afu hand, and my particular interest was in the kind of folklore in this post and specifically in folklore related to scientific topics. (And, yes, Snopes and Barbara are wonderful people and you can rely upon their voeracity.) The glass flows thing was my particular specialty.

I am most interested in the psychology of this. There is a particular attraction, to a particular kind of personality, in knowing certain "facts" like those we're discussing. It speaks to a kind of need to be knowledgeable, to have had a peek behind the curtain. I know that I'm such a person. I really think the glass flows folklore is almost archetypical in this way because it's so counterintuitive. It really does make one feel like one has seen behind the curtain, that one is "in the know" about a bit of natural science.

And so, individually and collectively, people can have a much stronger investment in these things as being true than we might otherwise expect. Being "right" about these things involves a certain amount of self-esteem, of feeling informed and smart. So having any of these things challenged quite often results in a surprisingly strong defensive response.

That's one way in which this sort of folklore functions similarly to the more familiar varieties of urban folklore. But there are others, too. Oftentimes, this folklore is successful because it validates certain prejudices. The 10% of the brain folklore is often most strongly believed by those who have a big investment in believing that most other people are not very smart because they're lazy, they're just not rigorously using all the potential of their brains. The Great Wall one is attractive to those who wish to puncture the hubris of modern supremacy. The Eskimos "snow" one is attractive to anyone who wishes to assert some form of cultural relativism for whatever purpose. (And those purposes are apparently infinitely varied, as the ongoing widespread use of this bit of folklore and the generalized snowclone shows.)
posted by Ivan Fyodorovich at 2:32 AM on February 5, 2012 [3 favorites]


Drinking more water would probably replace many of the others through lowering the thirst that drives people to drink soda or beer.

Why on earth would you want to do that? Even if we're all dehydrated without knowing it, because of confusing hunger and thirst and whatever, why can't we just rehydrate with soda and beer? I like soda and beer. Soda and beer also happen to be made almost entirely of water. If anyone wants to give me free soda and beer for saying this....
posted by howfar at 5:04 AM on February 5, 2012


Why on earth would you want to do that? ... why can't we just rehydrate with soda and beer?

Soda, maybe. Beer- not so much:
DEHYDRATION
Alcohol is a powerful diuretic that can cause severe dehydration and staggering electrolyte imbalances.
As if that weren't enough:
Alcohol, when consumed in amounts typical with binge drinkers (most common among college athletes), can dramatically decrease serum testosterone levels.
posted by Kirth Gerson at 5:15 AM on February 5, 2012


Well, I wasn't suggesting solely relying on beer for hydration, nor binge drinking. We could play the citation game all day, of course, but this fairly anti alcohol review suggests that beer hydrates more than dehydrates, and that normal 4% beer does not increase urination. With regards to the whole 8 x 8 thing, this seems like a fair summing up, and includes reference to the hydrating effect of moderate beer consumption.
posted by howfar at 5:54 AM on February 5, 2012


First link should go here.
posted by howfar at 5:56 AM on February 5, 2012


People actually believe that blood in veins is blue? Good god. What educationally-benighted part of the world does that happen in? Indiana?

(timidly raises hand)

That would be me. Educated in Ohio and Minnesota.

I do think this is a widespread belief. If it's false, I need a better explanation. "No oxygen in syringes" sounds wrong to me. I would assume that there is just as much oxygen in an empty syringe as there is in the open air. I don't believe that syringes are complete vacuums. I think the plastic walls of a syringe would collapse if this were so.

Feel free to school me.
posted by marsha56 at 7:26 AM on February 5, 2012


Just to clarify, I'm quite willing to believe that I have been mis-educated on this point. I just need a better explanation of why this is wrong.
posted by marsha56 at 7:30 AM on February 5, 2012


For everyone who saw Contagion the statistic about how often people touch their faces is very memorable.

I watched Contagion by choice on a plane crossing the Pacific while coming down with what I would realize was the Hong Kong flu: chills, shaking, the soaking sweats, pain in every joint in my body, and coughing, accompanied by a movie that shows us Gwyneth Paltrow dying of a febrile seizure and getting her scalp peeled off. Worst flight of my life.
posted by KokuRyu at 8:18 AM on February 5, 2012


"No oxygen in syringes" sounds wrong to me. I would assume that there is just as much oxygen in an empty syringe as there is in the open air. I don't believe that syringes are complete vacuums. I think the plastic walls of a syringe would collapse if this were so.

When a syringe is empty, the plunger is pushed all the way to the front. The only air is in the needle itself. What you seem to be arguing is that even that tiny amount of air somehow instantly converts blue venous blood into red blood, even in largish amounts of blood like a blood donation.

I don't know what it would take to convince you that venous blood is red, but The Straight Dope has an explanation (over-simplified, IMO) for why and includes a simple experiment for how it works. And here's another explanation, with the observation that unopened veins are not blue during surgery.
posted by dirigibleman at 9:17 AM on February 5, 2012 [2 favorites]


Checking Wikipedia, it turns out that it's not actually the Eskimos, but the Sami people who have at least 175-180 different word stems for snow and ice (The number is for the North Sami language).
posted by ikalliom at 11:09 AM on February 5, 2012 [1 favorite]


When a syringe is empty, the plunger is pushed all the way to the front. The only air is in the needle itself. What you seem to be arguing is that even that tiny amount of air somehow instantly converts blue venous blood into red blood, even in largish amounts of blood like a blood donation.

(egg on my face).

Obviously not a nurse or a phlebotomist, I had completely forgotten that of course the plunger is pushed all the way down, and so the syringe truly doesn't have hardly anything in it.

Thanks much for the explanation dirigibleman!

Also thanks for linking to the Straight Dope on this. For some reason I feel reassured to realize that even if venous blood isn't blue, there is a color difference. Venous blood is dark red, and freshly oxygenated arterial blood is bright red.

Anyway, thanks much for educating me today.
posted by marsha56 at 11:28 AM on February 5, 2012


The ancients, and basically everyone, were aware of a difference between arterial and venous blood. Aristotle and Galen thought that the differences had to do with nutrients and cooling/heating, relating to those different functions of the heart and liver and lungs. William Harvey in the early 1600s showed that blood was actually pumped circuitously through the body continuously (with much elaboration and faultless argument from evidence—his Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus is really a beautiful and significant piece of empirical science). But it wasn't until William Lower in the late 1600s that the relationship between the different coloring and exposure to air was noted.

I suppose that the notion that venous blood is blue rather than dark purple-red arose from a conjunction of a partial, folk understanding of oxygenation and the circulatory system with the observation that blood vessels look blue under the skin. And it's likely that color illustrations of the circulatory system using blue and red contributed.

It's worth noting that, arguably, all knowledge is like this. In science, especially, it's sort of a not-entirely-true-but-not-entirely-false joke that everything you learn in an intro course you'll later learn is false. Incomplete knowledge is either specific-but-isolated or generalized. But all knowledge is incomplete. So the choice is either to collect discrete, unintegrated facts that don't mean much, if anything, on their own, or to generalize in a way that necessarily involves some degree of miscomprehension. I'm not sure if the former, as a rule, is actually possible for anyone, as it's just not how our minds work. So, mostly, we build incomplete and somewhat confused understandings of the world that we (hopefully) add to and correct as we go along.

So it's nothing to be ashamed of to be wrong about these things, because we're all wrong in similar ways about pretty much everything. The only wrong is to not accept correction and addition when one continues to learn.
posted by Ivan Fyodorovich at 2:30 PM on February 5, 2012 [3 favorites]


Thanks for the kind words Ivan.
posted by marsha56 at 3:42 PM on February 5, 2012


In the context of Ivan's last comment, it's probably worth mentioning that this research paper has been one of the top 5 most read papers on Mendeley since the very beginning.
posted by Mr. Gunn at 9:00 PM on February 5, 2012


"Thanks for the kind words Ivan."

You're welcome. :)

I wrote and have maintained (thought not updated, alas) the web's oldest page/site on the Monty Hall Problem. For, um, 16 years now I've been corresponding with people around the world about the problem and it's been very interesting and a continual opportunity to learn.

And, well, what I've come to strongly feel is that it's not that important that one actually knows the correct answer to the problem, so much as it's important both whether one understands what one knows...and how one responds to external challenges to that presumption of correctness. It's pretty easy for people to read a treatment of the problem, and therefore "know" what is the correct answer; but it's often the case that it's those who get the answer wrong who have a stronger comprehension of the subject matter than those heard or read the explanation once, thought it made sense to them, and didn't think much more about it.

As if often the case this imperfect understanding can be revealed when one attempts to explain or teach something to others. This is one way in which corresponding with skeptics about the correct answer over the years has greatly increased my comprehension of the problem.

The one frequent behavior among my skeptical correspondents which, even after all these years, still deeply confounds me is that I implore many of them to simply test their conclusion about the problem empirically—write a computer program, or simulate numerous iterations of the problem with a friend. Or, if not with empiricism, a trusted authority. Call or email a local mathematician or statistician (anyone with strong expertise in probability). Look up the citations I include in my page. None of these things are that difficult. But a portion of these correspondents simply refuse to do so. They are so sure of themselves, that they believe it's not necessary. Or, in one memorable case of a major metropolitan newspaper science reporter, he said that even though he was considering doing a piece on the problem, it wasn't really important enough for him to verify or disprove his (mis)understanding of it. No kidding.

Finding out one is wrong about something is not shameful—in fact, it's admirable because knowing anything at all about anything is a continual process of finding more and more ways to be less and less wrong. If you're not open to the possibility of being wrong, then you can't ever move forward. And, given that we can't ever escape being totally or mostly or at least partly wrong about pretty much everything, our choice is to learn to see the opportunity for correction as a boon, or to simply be as willfully ignorant or deluded as possible.
posted by Ivan Fyodorovich at 11:10 PM on February 5, 2012 [3 favorites]


That Monty Hall problem is great - it seems so very simple, but there's a lot under the surface, and every time I think I understand it, and put it down for a while, I come back and it again seems too bizarre to be true. And it's really, really hard to explain it, even when I feel like I understand it.

I had some fun thinking about it, and came to the conclusion that in a generalized Monty Hall problem, where there are

n prizes
m duds
d = n+m total doors

(but the host still reveals just one of the duds after you choose) then the ratio of the probability of winning via the switching strategy to the probability of winning via the staying strategy (i.e. the advantage of the switching strategy) is

d - 1
-----
d - 2

!! It doesn't depend individually on the number of prizes or duds, just the total number of doors! If there is only 1 prize, and 1001 duds, you're still 1.001 times more likely to win if you switch!

Finding out one is wrong about something is not shameful—in fact, it's admirable because knowing anything at all about anything is a continual process of finding more and more ways to be less and less wrong. If you're not open to the possibility of being wrong, then you can't ever move forward.

Also, I like this attitude a lot, and think the sentiment is quite true. As a teacher, I feel like it's really important that I take this to heart for myself and for my students. It's not always easy getting my ego out of the way when I'm wrong, but I'm working on it.
posted by Salvor Hardin at 11:26 PM on March 1, 2012


That Monty Hall problem is great - it seems so very simple, but there's a lot under the surface

If I may, I think you've got it backwards. It's very simple, but it seems there's a lot under the surface.
posted by ShutterBun at 11:54 PM on March 1, 2012


in one memorable case of a major metropolitan newspaper science reporter, he said that even though he was considering doing a piece on the problem, it wasn't really important enough for him to verify or disprove his (mis)understanding of it.

That's Clark Kent for ya.
posted by ShutterBun at 11:56 PM on March 1, 2012


"If I may, I think you've got it backwards. It's very simple, but it seems there's a lot under the surface."

I think I understand what you mean, but, all things considered, I disagree.

In the technical sense, it really isn't an easy problem. That is to say, it's not a classical probability problem and it can't be properly understand that way. It's a conditional probability problem, which is something that pretty much everyone except those specifically trained in this overlook. You can get the gist of what's going on by thinking about it in classical terms, and that's how I approach it on my page, but from a technical standpoint, it's misleading. There's a school of thought that is very strongly opposed to any presentation that's not conditional probability.

But in the larger sense, I very strongly think there's a lot going on with the problem. To me, it exemplifies a class of problems where the intersection of some knowledge/education and intuition conspire to create a tenacious miscomprehension. I find this class of problems very interesting. And, more generally, I find developing an intuition about the problem and how to teach other people to correctly understand it to be itself of great interest.

So, I think there's a lot going on with it.

"It doesn't depend individually on the number of prizes or duds, just the total number of doors! If there is only 1 prize, and 1001 duds, you're still 1.001 times more likely to win if you switch!"

Right.
posted by Ivan Fyodorovich at 4:38 AM on March 2, 2012


Hrrmmm...I think the only thing preventing mathemeticians from instantly solving the Monty Hall problem is to somehow incorporate the fact that Monty will (obviously) NEVER reveal the winning door during Phase 2 of the dilemma. From then on, it's simple math:

Question: What are your odds of having guessed right the first time? (Answer: 1 in 3)

From there, it's a simple matter of "guessed right and switch" or "guessed wrong and switch"

Since we already know that the odds favor a "wrong" guess at the outset, AND that we cannot go from a "wrong" guess to another "wrong" guess, it's profoundly obvious.

I have a feeling that most math formulas have a hard time expressing an omniscient operator (i.e. Monty Hall) into their equations, thus are forced to treat Round 2 as a 50/50 proposition.

Given the way most people think, I guess it's probably wrong of me to suggest that it's a really simple problem. (after all, isn't being "right" or "wrong" merely a 50/50 chance?)

And you're right, there definitely IS "a lot going on with it," which I'm sure the producers of "Let's Make A Deal" realized. (The Mythbusters tackled this question not long ago, and it was AMAZING how many people simply refused to change their choice, based on "instinct, or whatever."

But come on, in a technical sense, it's a TOTALLY easy problem. Perhaps if the idea of "right" or "wrong" were eliminated, it would reduce people's self-reliance, or ego, or whatever it is that makes them not want to switch.

Maybe, tell them "there are 2 blue doors and one red door; we want you to pick the red door."

Tell this to the players: You probably chose a blue door. In fact, you're twice as likely to have guessed blue as to have guessed red. (nobody could argue with this)

Then say: If you guessed blue and switch, you end up with red. (since you can't switch from Blue to Blue) Given that you have a 2-in-3 chance of having picked Blue, wouldn't you opt to switch?

But no, I guess the human brain still wants to believe it's making a second 50/50 choice. No way around it. But that's what I mean: mathematically, it's pure and simple. It's all the other baggage that our brains carry around that makes it seem complicated.

And of course the most satisfying thing is that even now in the days of total information availability that we live in, it can still be used to incite riots at Thanksgiving dinners.
posted by ShutterBun at 5:08 AM on March 2, 2012


"I think the only thing preventing mathemeticians from instantly solving the Monty Hall problem..."

No, there's two things.

First, again, this is not a classical probability problem. You cannot formally analyse this outside of conditional probability.

Second, most people with any education in probability, which includes all mathematicians, will tend to see this as a problem involved the Gambler's Fallacy. That is, everyone who learns introductory probability has it drummed into their heads that random events are independent. So the trained instinct is two see the two choices as being unchanged in terms of probability.

Finally, historical evidence indicates that, oddly enough, mathematicians are quite prone to getting the answer wrong. Each time (though less and less every time) the problem erupts into the public consciousness, there are notorious incidents of mathematicians who are aghast at the claims that it's better to switch than to stay. There's been a lot of embarrassment about this.

A good portion of the people who have contacted me about the problem over the years have been students and even teachers in math and probability.

However, the world is much different than it was in 1995 when I first wrote my page on the MHP, and it's certainly much different than when Marilyn vos Savant answered the problem (correctly) in 1990 in Parade Magazine, and it's even more different from when Martin Gardner mentioned it in Scientific American. Mine was the first and only resource on the web about the MHP for a while, about eight months, then there was another guy who also put up a page, then through the rest of the nineties there were more and more resources available about it. The Wikipedia entry on it is extensive (and you should look at the talk pages to see some heated argument about presentations of the problem in any form other than conditional probability). In association with this is my strong suspicion that the MHP is being actively taught in many university classrooms these days.

So, all told, there's far fewer people who ought to know the solution to the problem, but don't, than there were in the nineties. But, believe me, unless someone has been specifically introduced to this problem, even among mathematicians there's a strong tendency to be confused about it.

I don't think it's merely that the human brain wants to see it by default as a 50/50 choice. If you see two closed doors and are asked to pick one, then do, and then Monty says, well, the one you picked is the losing door and the other one is the winning door, do you want to switch, everyone will understand that it's not 50/50. The trick of the problem is in getting people to see—and this most certainly includes mathematicians and others who should be more adept at this problem—that Monty is forced to reveal information in the course of the problem. One big reason why this is hard for people to see is because Monty isn't always forced to reveal any information...he's only forced to do so when the contestant initially chooses a losing door. This is why it's a conditional probability problem. A formal analysis requires a branched analysis of the probabilities, and classical probability cannot do that.

Anyway, it's a mistake with things like these, where lots of smart people don't understand something that seems obvious to oneself, to assume that it's easy and all those other smart people are just not as smart or clearheaded or whatever as oneself. I mean, that may be true in that particular case, but it's likely that one is one of those confused or not-smart people with regard to a different, commonly misunderstood, problem. Or, to turn this around, the one thing that is almost (but not quite, though close) universal with the people who get the MHP wrong is that they're absolutely sure that it is they who are the smart and clearheaded people and it's the people who think it's better to switch who are the stupid and/or confused people. So, the point is to beware of hubris about these things.

Which, again, is one of the things about this that most intrigues me. On my page, I practically beg people to consider that there might be a good reason that people believe that it's better to switch and that there's nothing to lose by actually testing their intuition/analysis of the problem empirically. Of course, I don't know how many people go on to do this (which is, by the way, what I immediately did when I first read about the problem in 1990), because I'm less likely to hear from them, but I sure do get emails from people who are absolutely certain that I and everyone else who says that it's better to switch are just totally wrong and they're going to explain it to me. And, then, again I urge them to actually do some form of experiment.

People are weird.
posted by Ivan Fyodorovich at 8:10 AM on March 2, 2012


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