Wikipedia:Reference desk/Archives/Science/2016 March 7

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March 7

Reverse Correlation Method

Hey Guys, I have a psychology assignment that I am doing, and I was reading a study, titled Seeing Jesus in toast: Neural and behavioral correlates of face pareidolia. In the text, it contained a passage: We, for the first time, directly compare the neural responses of face pareidolia to that of non-face object (letter) pareidolia. Specifically, we explore the specific role that the FFA plays in face pareidolia. In the present study, participants were instructed to detect faces from pure-noise images in the face condition, and letters from the same pure-noise images in the letter condition. To ensure that face or letter pareidolia really occurred, we used a reverse correlation method similar to that used by Hansen et al. (2010) to obtain classification images based on behavioral responses (face or no face response in the face condition and letter or no letter response in the letter condition).  I do not know what reverse correlation method is. I tried going on the Wikipedia page for it, (Spike-triggered average) but found it was a lot of jargon. If anybody knows anything about what it is, I would be very thankful. JoshMuirWikipedia (talk) 08:28, 7 March 2016 (UTC)

You haven't adressed the most obvious line to take: Did you look up Hansen et al (2010)? If not why not? If yes, give us the compplete harvard reference and tell us why it didn't help you. 60.228.17.3 (talk) 10:43, 7 March 2016 (UTC)

The article Fusiform Face Area (FFA) describes the part of the brain involved in face recognition. Correlation is a mathematical measure of the consistent relationship between two sets of data. Although correlation does not always imply causation, we do suppose that neurons emit spikes as a response to preceeding stimuli. So-called "reverse correlation" is the collection and averaging of historical data that preceeded every spike. The procedure to obtain a Spike-triggered average is to record all the stimuli as a continuous time record, then detect each spike time and finally look backwards in time at the stimuli that were recorded prior to the spike. This diagram demonstrates study of a neuron that is sensistive to a bright spot in the visual field, but whole face recognition and facial illusion (paraidolia) are more complex psychological phenomena. AllBestFaith (talk) 13:31, 7 March 2016 (UTC)

• Let me try to describe the method as simply as I can.

1. Start with a set of completely random images. Participants look at them and claim to see faces in some of them but not in the others.
2. Average together all the images in which participants claim to see faces, and separately average together all the images in which they claim not to see faces.
3. Subtract the averaged no-face image from the averaged face-image. The result is called the Classification Image.
4. The claim is that this Classification Image has a structure that more or less resembles a picture of a face.

Looie496 (talk) 19:03, 7 March 2016 (UTC)

This paper has a fairly accessible description of the method. Tevildo (talk) 00:09, 8 March 2016 (UTC)

Wi-fi

Can an operating microwave oven interfere with a wi-fi connection? 2601:646:8E01:515D:FC5A:F45A:C719:3885 (talk) 10:32, 7 March 2016 (UTC)

Yes, potentially quite a bit. As our article says, Wi-Fi b and g use the same range of frequencies that microwave ovens do. One technique to mitigate this is to switch between Wi-Fi "channels" (frequency bands). A lot of Wi-Fi equipment includes features to automatically switch channels if needed (often referred to by names like "Auto channel select"). --71.119.131.184 (talk) 11:25, 7 March 2016 (UTC)

YES - along with quite a few other things. Apple gives a list of the main sources of interference here: https://support.apple.com/en-gb/HT201542 109.150.174.93 (talk) 11:49, 7 March 2016 (UTC)

Microwave ovens are supposed to be shielded, with a Faraday cage. That's the fine wire mesh you see in the door. It's also behind the plastic on the sides, top, and bottom. StuRat (talk) 14:36, 7 March 2016 (UTC)

Microwave ovens operate at ~10,000 times the power output as wifi. A microwave can be legally compliant if it "only" blocks ~99.8% of the power output, which would mean it still emits 20 times higher than what a wifi router is allowed to emit. It is easy to see how microwave oven could interfere with wifi. Whether or not they actually will interfere generally depends on the quality and integrity of the shielding. Dragons flight (talk) 16:48, 7 March 2016 (UTC)

Why metering devices are based on different standards and different etalons?

If economics are always based on standardization and certification (based on standards and etalons), so why metering devices are based on different standards and different etalons (based on different standardization and different certification)?

Did the USSR-Russia are used international standards and international etalons in their standardization and certification of metering devices on which been based their economy?--83.237.197.222 (talk) 13:00, 7 March 2016 (UTC)

Therefore, did the economy as also and metering devices should be objective or subjective?--83.237.197.222 (talk) 13:15, 7 March 2016 (UTC)

In the USSR only electricity meters had been compulsory for all, so that in the USSR were no been gas meters and water meters in households because gas and water were always paid according to fixed state tariffs, and in Russia it is mandatory for all added water meters but not gas meters.--83.237.198.253 (talk) 14:27, 7 March 2016 (UTC)

According to wikt:etalon, it's a device for delaying a laser beam. Is this really what you meant ? StuRat (talk) 14:32, 7 March 2016 (UTC)

Sorry - but your question is very hard to understand - particularly, the word "etalon" that you use four times means: "An optical device containing parallel mirrors, used in laser design to delay light"...which probably isn't what you mean here. I assume you are using automatic translation from Russian into English - but it's not working well enough. Can you find someone who speaks English to ask the question for you? SteveBaker (talk) 14:34, 7 March 2016 (UTC)

Etalon is French for a measuring gauge or a measuring standard - so the standard meter or the standard kilogram is an etalon. I suspect this is the meaning here - but the question still isn't clear enough to know what is actually being asked. 109.150.174.93 (talk) 14:41, 7 March 2016 (UTC)

Ah - OK, so maybe we can have a shot at answering it... SteveBaker (talk) 16:51, 7 March 2016 (UTC)

• If economics are always based on standardization and certification (based on standards and etalons) -- I don't think economics are based on standard measurement methods. Clearly, when you're talking about the value of goods, you have to know how much goods are involved - but it doesn't seem to be an important part of economics.
• so why metering devices are based on different standards -- Are you asking about why (for example) some markets measure using the metric system and others on imperial units? It's usually very clear what goods are sold using which units of measurement (gallons versus liters, feet versus meters, pounds versus kilograms, etc)...and there are standards for converting between them - so it's really not much of a problem. That's not always true - if you cut wood or paper into sizes that are standard in one country - but not in another, then there will be problems. If you sell A4 sized sheets of paper, you're not going to sell much in the USA, where people normally use "Letter" sized sheets...but if you sell gasoline by the liter, you'll have no problems selling it in US gallons. Everything depends on what the item you're selling is.
• Did the USSR-Russia are used international standards and international etalons in their standardization and certification of metering devices on which been based their economy? -- Most places in the world choose the standards they use for historical reasons rather than for economic reasons. But if you trade all around the world, choosing the metric system is generally easier.

I hope I answered the right question! SteveBaker (talk) 16:51, 7 March 2016 (UTC)

Some other examples where unit conversion doesn't work come up with food, which is sometimes measured by weight, sometimes by volume and sometimes per item. It's not that easy to compare a pound of apples with a peck or with a dozen. You need to know the average volume, mass, and how tightly they are packed (and, due to edge effects, large quantities may be packed more densely). In the case of things like brown sugar, the volume to weight (or mass) also depends on the water content. Of course, none of this relates directly to the Q. StuRat (talk) 17:48, 7 March 2016 (UTC)

I interesting, did it make sense to install meters (metering devices) if their readings are not standard and etalon (measuring gauge) according to the international standardization and international certification of their?--83.237.195.181 (talk) 17:34, 7 March 2016 (UTC)

I believe we already answered. To repeat, it doesn't matter what units are used, as long as those units can easily be converted into any other units. StuRat (talk) 17:43, 7 March 2016 (UTC)

And as for the why any country would not chose an international standard, in short old habits die hard --Lgriot (talk) 17:56, 7 March 2016 (UTC)

There are up-front expenses with switching standards, and politicians tend to be incredibly short sighted, so the long term benefits may be irrelevant to them, compared to the short terms costs. StuRat (talk) 18:03, 7 March 2016 (UTC)

And in Russia, IP addresses jump around even more than in the United States or the United Kingdom. Robert McClenon (talk) 18:16, 7 March 2016 (UTC)

Thanks StuRat. However, did it make sense to install meters (metering devices) if the word economies already have a depreciated cost (residual value – liquidation value) due to the depletion of natural resources, in my country USSR-Russia it had been due to the depletion of natural gas resources?--83.237.195.181 (talk) 18:58, 7 March 2016 (UTC)

I don't quite understand. Are you saying the cost is too low to worry about metering it ? The cost of something has to be extremely low for that argument to be true. Even water is typically metered when delivered by pipe to homes. It could be delivered for free, and just use taxes to pay for it, but then peole would tend to waste water, since it won't affect their bill. StuRat (talk) 19:36, 7 March 2016 (UTC)

StuRat, I mean that the profit is extremely low due to the residual value – liquidation value which already presents in the world economics, so that I think that there is not sense to install meters (metering devices).--83.237.200.134 (talk) 20:01, 7 March 2016 (UTC)

StuRat, low profit did not make chance to successfully develop economies of the world.--85.141.239.105 (talk) 21:10, 7 March 2016 (UTC)

It may be that we aren't answering the original poster's question because we don't understand it. Does the Russian Wikipedia have a Reference Desk? Robert McClenon (talk) 21:14, 7 March 2016 (UTC)

ru:Википедия:Форум/Вопросы. Nimur (talk) 21:18, 7 March 2016 (UTC)

Thank you for answering that question. Original poster: We have difficulty in understanding your question, largely because it isn't in clear English. If Russian is your first language, as we would guess from your IPs geolocating to Russia, why not ask the question in Russian at the Russian Wikipedia? Robert McClenon (talk) 21:21, 7 March 2016 (UTC)

"Вопросы, не относящиеся к работе над Википедией, будут удалены." I suspect they will not tolerate this type of question on the Russian Wikipedia reference desk. Nimur (talk) 23:43, 7 March 2016 (UTC)

There may be it sense a residual value - liquidation value of the national currencies of the economies of the world.--83.237.207.66 (talk) 07:13, 8 March 2016 (UTC)

My country USSR-Russia did make the stupidest thing to becoming saving an electricity at the beginning of its development, installed an electricity meters and to becoming saving a natural gas at the end of its development, beginning to install a water and natural gas meters.--83.237.207.66 (talk) 07:29, 8 March 2016 (UTC)

In the end it will be possible to learn from my country USSR-Russia has justified its banking on natural gas or not.--83.237.197.166 (talk) 10:23, 8 March 2016 (UTC)

Dependence on any one industry will eventually lead to economic collapse when that industry declines. I am in Detroit, which has suffered from economic collapse as a result of over-dependence on the automobile manufacturing industry. Theoretically, you could have taken all the profits from natural gas and used them to develop other industries for when that industry declines. However, actually doing so require extreme discipline which is lacking just about everywhere. We didn't do it in Detroit, Russia doesn't appear to have done so with gas, and Saudi Arabia doesn't seem to have done so with oil. For an example of where it has been more successful, maybe look at the economy of Hawaii, which at one time was dependent on tropical crops, like pineapples (and before that, whaling). They have been able to diversity into other industries, like tourism. StuRat (talk) 15:38, 8 March 2016 (UTC)

Thank you StuRat. The main age-old quests problem of my country USSR-Russia is that, did a natural gas turned out more cheap than electricity for it or not.--83.237.205.112 (talk) 16:39, 8 March 2016 (UTC)

As for me, it is be often interesting why my country USSR-Russia choose their banking on natural gas against to electricity.--83.237.207.147 (talk) 18:45, 8 March 2016 (UTC)

Having large reserves of natural gas makes that look promising, while electricity has to come from somewhere, like nuclear power plants, and Chernobyl makes those look like a bad idea there, while transmission of electricity over vast distances causes losses due to resistance. StuRat (talk) 19:05, 8 March 2016 (UTC)

Since my country USSR-Russia from the very beginning of its development already was saving electricity, it did forced to use electricity combined with natural gas at the end saving natural gas, I think it been cheaper for its development than using only electricity.--83.237.201.20 (talk) 07:58, 9 March 2016 (UTC)

Of course, I think that more simple combinations of electricity with natural gas are always been more effective – more cheap than more complex combinations of electricity with natural gas. — Preceding unsigned comment added by 83.237.201.20 (talk) 09:12, 9 March 2016 (UTC)

StuRat, agree, that than cheaper be the energy source so that been the more quickly pays for itself regardless of the technique which is be simple or complex. (Of course, for quickly pays for itself of more expensive technique is always been required a more cheap energy source.)--83.237.203.184 (talk) 13:53, 9 March 2016 (UTC)

It's not always best to use the cheapest energy source. Since fossil fuels like natural gas are not renewable, it may make sense to save them for later, when hopefully the global supply will be lower and the price will be much higher, even if that means using a more expensive energy source now. This means saving a valuable resource for later generations rather than exploiting it today, though, which is rarely popular with politicians. StuRat (talk) 17:36, 9 March 2016 (UTC)

StuRat, Is it meaning that in terms of cheapest and most cheapest energy sources the level of complexity of technique never did not matter for pays for itself, because it did so fasters?--83.237.206.41 (talk) 19:54, 9 March 2016 (UTC)

(StuRat, is it be possible that natural gas development was turned out more cheap to my country USSR-Russia than electrical development?)--83.237.206.41 (talk) 20:28, 9 March 2016 (UTC)

StuRat, So what civilization did win a gas civilization or electricity civilization?--83.237.206.78 (talk) 16:58, 10 March 2016 (UTC)

Of course, than more cheaper be the energy source that been more fasters the paybacks, regardless of the level of complexity of technique which using this cheaper energy source.--83.237.206.78 (talk) 17:33, 10 March 2016 (UTC)

StuRat, So, what turned on, if gas been none technological, been none functional, but be cheap?--83.237.207.144 (talk) 18:55, 10 March 2016 (UTC)

Of course, an electricity always been the more best than gas, but gas be cheap.--85.141.237.62 (talk) 09:13, 11 March 2016 (UTC)

StuRat, I been thinking that in respect of all gases and in particular of all natural gases must been use only the most simplest technique, because all gases are always been none technological and none functional.--83.237.200.224 (talk) 10:15, 11 March 2016 (UTC)

At last, should be economy as also and accounting systems been objective or subjective?--83.237.205.112 (talk) 13:58, 8 March 2016 (UTC)

Wherever possible, everything should use objective measures. But, it's not always possible, therefore subjective (opinion) measures are sometimes all that we have. For example, a school teacher can objectively evaluate a student's math answers, but must subjectively evaluate an essay. StuRat (talk) 15:22, 8 March 2016 (UTC)

StuRat, Did it according to metering devices (meters)?--83.237.205.112 (talk) 15:33, 8 March 2016 (UTC)

A metering device should always be objective. I don't see how it's even possible for a meter to be subjective (some places did at one time have the customers mail in the readings, so maybe that's what you mean ?) . StuRat (talk) 15:42, 8 March 2016 (UTC)

StuRat, If economics are always been based on know-hows, so that did these know-hows are been standardized and certificated according to international standards, if they been a meters?--83.237.205.112 (talk) 15:49, 8 March 2016 (UTC)

I don't understand this question. StuRat (talk) 19:05, 8 March 2016 (UTC)

StuRat, If economics are always using know-how, some of them are been technical know-how, so that did these use's know-how are been standardized and certificated according to international standards, if they been a meters or been using in meters?--83.237.203.184 (talk) 14:30, 9 March 2016 (UTC)

Muscle memory

I don't want to be led astray too much by a mere choice of words for a concept, but could it be that muscle memory implies memories stored in muscles too? If you train a movement, could a muscle codify information about it in itself, that's posteriorly triggered by the brain?--Llaanngg (talk) 13:51, 7 March 2016 (UTC)

No. You should read muscle memory for more details if you are interest. The term is colloquial, and does not mean that the muscles themselves store memories like your central nervous system does. --Jayron32 14:08, 7 March 2016 (UTC)

(EC)Sure, that is a conceptually reasonable implication to look in to. But it happens to be not true. See Muscle_memory. It's not clear to me whether your interest is more in the logic of the matter or the actual science. Lots of things have logical possibility yet are not true, however most things that are logically impossible are not true. While it's not true that human muscle stores memory, memory can be stored in odd ways. Memory in general is a bit nebulous, and here [1] is some research that made a splash a few years back discussing how certain behaviors of slime molds seem to indicate they have memory. SemanticMantis (talk) 14:13, 7 March 2016 (UTC)

I get from the corresponding article that the mainstream view is that muscles do not store information. I suppose that includes that the synapses in the muscles (that is they do not store information either). However, how can we scientifically test whether memory is stored outside the brain too? The spinal cord has neurons whose axons project into the muscles. Could it be at least that a signal does not have to travel all the way to the brain, but be dealt with locally by the neurons of the spinal cord? --Llaanngg (talk) 14:59, 7 March 2016 (UTC)

There is compelling evidence for plasticity in the spinal cord; see for example PMID 11520919. Note though that most neuroscientists tend to think of the brain and spinal cord as parts of the same entity, the central nervous system. In any case there is no clear boundary separating the brain from the spinal cord; they merge continuously into one another. A more interesting question is whether there is plasticity in the peripheral nervous system -- I don't know the answer. And there is at least one part of the body other than the nervous system that shows a substantial learning capacity: the adaptive immune system. Looie496 (talk) 15:16, 7 March 2016 (UTC)

You might also be interested in the reflex arc and peristalsis, two cases where muscles are controlled, at least in part, locally. The beating of the heart may also fall into this category. However, there is no "memory" in these cases, as these forms of muscle movement are present at birth. The movement of long thin animals, like snakes, worms, centipedes, and millipedes, also seems to work in a manner similar to peristalsis. That is, the brain of the animal starts the front segment moving, but each following segment moves in turn right after the segment in front does, based on inputs from the previous segment. StuRat (talk) 14:29, 7 March 2016 (UTC)

A large part of the autonomic nervous system can operate independently of the brain and spinal cord and form memories, in particular the stomach can independently remember your pattern of eating and does not depend on the brain to prepare for a meal at the right time. In general though what is called muscle memory refers to learnt actions which are controlled by the cerebellum and need not go anywhere near conscious awareness. Dmcq (talk) 17:00, 7 March 2016 (UTC)

The section Muscle memory#Music memory says "Memorizing is done by muscles....[22]" with a citation to an 1896 paper in the American Journal of Psychology. Clicking to this link gets you to a free copy of the article, which says on page 454: "It was not, then, a reproduction of the word as heard or as associated with something seen, but of a muscular movement, which, latent for five years, was recalled by the suggestion of a similar movement. This incident suggests that possibly, under normal conditions, the muscles play a greater part in our memories than we are accustomed to assign to them". Loraof (talk) 14:57, 7 March 2016 (UTC)

I'd be more than a little skeptical of a 120 year old study involving memory, as they knew almost nothing about how memories were stored, at that time. StuRat (talk) 15:23, 7 March 2016 (UTC)

I have removed that source from the article, as well as the statements based on it. Looie496 (talk) 15:38, 7 March 2016 (UTC)

It might be good for the history section. StuRat (talk) 18:04, 7 March 2016 (UTC)

One aspect of memory that has always intrigued me is that memory can apparently survive metamorphosis in some animals e.g. [2] I always thought that during metamorphosis of the caterpillar, it temporarily became a "soup". Perhaps I am thinking of this too simplistically. DrChrissy ^(talk) 19:29, 7 March 2016 (UTC)

Much of it does, but some key organs seem to stay intact as they relocate to their new position. A fascinating process, isn't it ? StuRat (talk) 19:32, 7 March 2016 (UTC)

You mean imaginal discs, but they are not organs (yet) and they do not stay intact through pupation. It is by no means logically necessary that some physical organ must persist for learned behavior to persist, as shown by the unicellular slime mold I mentioned above, PNAS paper is here [3]. Anyway, we've now stumbled in to highly contentious cutting-edge research in entomology, wherein the "Hopkins host selection principle" and the "chemical legacy hypothesis" still vie for prominence and acceptance and nobody knows for sure what's going on [4] [5], [6]. This is indeed a fascinating direction for a thread on memory to go, but I'd be hesitant to take the one PLoS paper above as evidence of anything other than the latest punch in science fight that has lasted about a century. SemanticMantis (talk) 19:52, 7 March 2016 (UTC)

Ecdysozoans and even holometabolous insects don't really become a "soup" during metamorphosis. Their regeneration is something like an extreme specialization of how our own works: small diploid cells go from stem cell to rapidly dividing population, then become polyploid, larger, terminally differentiated, and eventually get worn out and thrown away. The difference is just (in ecdysozoa) the growth evolved to be phased to minimize the periods when the skin is unprotected by cuticle (but it's not as straightforward as growth during the molting period, more the opposite - see [7]), and in holometabolans their differentiated cells get discarded all at once as the imaginal discs rapidly spread out and replace them across the entire exterior of the body. But there's always a zone where tissue comes from and a zone where old tissue is gotten rid of, whether we're speaking of a butterfly or our own skin. Wnt (talk) 20:28, 7 March 2016 (UTC)

More on the innervation [8][9][10]. There's still a bit I don't understand about the geometry of the process, but it should be clear that the rewiring is relatively local. Wnt (talk) 20:37, 7 March 2016 (UTC)

I have just read the slime mold paper cited by SemanticMantis. It is absolutely fascinating! As someone who has worked in vertebrate animal behaviour my entire career, "We challenged our slime mold..." as a quote will stay in mind forever! DrChrissy ^(talk) 21:17, 7 March 2016 (UTC)

The time to start worrying is when it challenges you back! Have I mentioned my conjecture that the Loch Ness Monster is a giant grex? {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 21:36, 7 March 2016 (UTC)

No, you haven't! And I'm sure I speak for most ref desk regulars when I thank you profoundly for your omission. SteveBaker (talk) 21:47, 7 March 2016 (UTC)

Physarum can also learn to anticipate periodic events, as this paper shows [11], and though they don't have a biomechanical model (yet), they have a nice conceptual differential equation model for how they think memory might be working. (And yes, I think this is still relevant to the notion of "muscle memory" loosely considered, and the biological study of where memory resides :) SemanticMantis (talk) 22:15, 7 March 2016 (UTC)

Probably not stored like memory but muscles grow and train through repetitive use. In that sense, there is a muscle memory as certain groups are trained more and differently than others and the repetitive nature makes that action less fatiguing than doing the same or similar task with different groups. If your a carpenter that uses a hammer in your right hand for years and then switch, not only is your brain unfamiliar, your muscles cannot perform at the same efficiency. --DHeyward (talk) 00:17, 9 March 2016 (UTC)