Proprioception: The Silent “Sixth” Sense
vox.com
vox.com
Some may argue proprioception is provided by touch, but by the same light smell and taste are inextricably linked.
We can also sense heat and humidity to some extent, we have some of the mechanisms needed to sense magnetic fields, but no compelling evidence (to my understanding) exists that demonstrates that we can.
It's just one of those things thats much fuzzier than we think
Many things that we are taught in elementary school have this property
Cf. https://en.wikipedia.org/wiki/Glutamate_flavoring https://en.wikipedia.org/wiki/Umami
I think of it as devices rather than physical process sensors, which are the building blocks. You have cells that can detect things like mechanical pressure or specific chemicals, and you have actuators that can trigger sensors. They get mashed up by evolution to create devices like balance detectors.
Then there's proprioception as mentioned in the article, the sense of balance/acceleration as measured in our ears, and together with smell, sound, taste and sight we are already at 9 senses.
And as you mention many of the things we actually perceive are derived from many senses. The "taste" of a steak is a mix of smell and taste, your balance is a mix of sight and your acceleration, temperature is something we can't actually fell but can derive from how much heat enters or leaves our body, "pain" is a giant category spanning nearly all senses, etc.
And pressure--i.e. texture.
Do you mean an itch or a sunburn-type discommfort or something else?
But your body keeps track of its speed and location in any environment regardless of if your senses are impaired (grid cells and place cells rely not only on sight but information gathered from speed and head direction cells), which is as much of a sense as proprioception. We don't even have a word for this, I think. Locoception, perhaps? Posiception? Only two Latin roots I know which fit.
https://en.wikipedia.org/wiki/Grid_cell
https://en.wikipedia.org/wiki/Place_cell
The innate sense of where you are in relation to your environment is... spatial frequency?
That doesn't sound right.
Ie “coil whine”.. not saying this guy isn’t a nut. But it is possible to hear electronic devices. On a computer streaming video the increased current demands can make power supply coils more audible.
Some people are sensitive to some frequencies.
An LCD shouldn't whine, but some can (bad capacitors, cheap power supplies, or any number of other causes).
[0] https://www.bloomsbury.com/uk/empire-of-the-senses-978185973...
Well you can easily sense charge if it's enough to lift your hair. We can also feel electric shock. I'm not sure if you want to categorize those as touch.
https://www.biorxiv.org/content/biorxiv/early/2018/10/20/448...
It creates a numbing sensation and when used with chili peppers of moderate heat, it tricks the mind into thinking that it’s hotter than it really is ..the tingling and numbing sensation leading to the nervous system trigger the same responses as though you are eating something excessively spicy and hot.
I want to say..maybe a rush of endorphins. If you had just the Sichuan peppers alone, there would be no spiciness or heat. Just numbing and tingling. It’s a neat hack.
The way we teach about the human condition is very limited, and I only started understanding a bit how my body works after I reached 30 thanks to a lot of self-experimentation.
Some of that is in the sense of Wittgenstein's Ladder -- a tool which suffices to gain a level of understanding but then must be discarded. Often also referred to as "lies told to children". Some is institutional and cultural resistance to new idears or release of the old. (This turns up in language, we speak of the sun rising and setting, of good and bad humours, of magnetic personalities, and of sky gods and goddesses, bearded or otherwise, despite varying degrees of disproof or lack of proof of their existence.)
So, yeah, you can pretty much drop most of your early education as being accurate.
That said, if you're interested in sensation and perception, there is an entire division of psychology devoted to that, and amongst the first myths demolished in my own textbook on the topic is the notion of five senses, and in particular that of a unitary sense of touch.
There's hope, if you look for it.
In particular children are being taught about basic arithmetic operations in a way that facilitates later showing them the larger picture. For example the consistent application of a "number line" and showing how operations involve counting up and down that line means later successor-of(), exponentiation, and the hyper-operators will fit nicely into the pattern rather than forcing a re-examination of what you learned earlier. Done right you can prime children to be shown Group Theory and just go "Oh, that makes sense" rather than having to re-examine what they learned already from a new perspective. Parents who've forgotten how long it took them to "just know" that 6 x 7 = 42 and don't have a strong mathematical background seem to rage at each iteration and then are further annoyed to discover that those of us who needed more mathematics later actually think these innovations are a good idea because now kids understand "why" 6 x 7 = 42 rather than just memorising it for a test...
Concepts of science, both natural and social, philosophy, logic, and history are others.
There's an (IMO) fascinating division in the teacing of skills versus "liberal arts" (ultimately: critical thinking, concepts of power and control) in education. What are now considered "technologies" had their beginning as "practical", "technical", or "servile" arts, contrasted with the Seven Liberal Arts:
- Grammer, Logic, and Rhetoric: the Trivium, from whence, "trivia". Think "input, processing, and output."
- Mathematics, Geometry, Music, and Astronomy: the Quadrivium. Think "quantity/measurement, quantity in space, quantity in time, and quantity in space and time."
This divide remains apparent in both lower ("tracking") and higher education. For the latter, top-tier "prestige" schools, followed roughly by major research universities (science), technical schools and polytechnics, what used to be called "teacher" or "normal" schools in the US (now mostly state college / university systems), two-year and vocational schools.
A huge problem of the pedagogical rigidity is the (usually) unstated goals of educational systems:
- Produce a technically-skilled, but politically pliable, working class.
- Produce a managerially competent, but not revolutionary, mangement and professional class.
- Persist existing power structures.
Observed by many over the years, including numerous 20th and a few 21st century commentators. I find John Stuart Mill's 19th century take interesting for its remove from immediate political machinations and for being possibly unexpected given the popular perception of his writings. See Hans Jensen's description, with cites:
First, the universities were given the task of providing an unceasing supply of ideologically correct candidates for vital positions in government, church, and business. The state was able to make the faculties of the "venerable institutions" of higher education, or rather indoctrination, assume this duty because it controlled appointments and held the purse from which "emoluments" flowed into the coffers of academics. Hence the members of the university "hierarchy" made it their "business, the business for which they ... [were] paid," to "uphold certain political as well as religious opinions," namely those of the "ruling powers of the state" (J.S. Mill, Autobiography and Literary Essays, p. 429 (1981), J.S. Mill, Journals and Debating Speeches, p. 350. (1988) ). Thus the universities pursued with vigor their assignment to inculcate in their students those political and ideological views that were cherished by the power elite. The graduates of the ancient universities were, therefore, well prepared for employment in, and by, those institutions that were instrumental in perpetuating the existing maldistribution of income. All of this might come to naught, however, if the masses of the underclass should achieve anything approaching success in potential attempts at throwing off their fetters.
The state devised a second educational strategy in order to prevent such a calamity from occurring. According to Mill, the "elementary schools for children of the working classes" were given the task of ensuring that the poor would continue to accept docilely their dismal station in life. It was very easy for the state to force the public schools to assume this role. It did so simply by failing malignantly to allocate sufficient funds for the operations of what Mill identified contemptuously as "places called schools" (J.S. Mill, Essays on England, Ireland, and the Empire, p.200; emphasis in original). These places were therefor understaffed. Moreover, the few teachers who were actually employed were completely "unfit for their work." The pupils therefore were so "wretchedly ill-taught" that they "did not ... even learn to read." And, said Mill with disgust, no attempt was "made to communicate ideas, or to call forth the mental faculties" of the children". (J.S. Mill, Public and Parliamentary Speeches, November 1850 - November 1868, p. 322 (1988). J.S. Mill, Essays on England Ireland, and the Empire, p. 200 (1982)).
Hans E. Jensen, "John Stuart Mill's Theories of Wealth and Income Distribution". Review of Social Economy. Pages 491-507. Published online: 05 Nov 2010.
http://www.tandfonline.com/doi/abs/10.1080/00346760110081599
Previously noted by me in:
https://old.reddit.com/r/dredmorbius/comments/6x7u6a/on_the_...
Borrowed from Schopenhauer, who actually made a better point about the goal: https://www.goodreads.com/quotes/301471-however-for-the-man-...
I've only recently really discovered Schopenhauer (having of course at least heard of him), and find his writing clear and appealing.
Wonderful online essays collection:
https://ebooks.adelaide.edu.au/s/schopenhauer/arthur/essays/...
("On Authorship and Style" was posted to HN a few months back.)
https://en.wikipedia.org/wiki/List_of_common_misconceptions#...
I also think there's a very strong cognitive/information processing in the moment aspect to athleticism as well- a general CPU motor that coordinates the speed, strength, proprioception etc. together in the moment. (Another aspect that I noticed I lacked growing up compared to others in sports)
This higher level processing is called intelligence, "bodily-kinesthetic" intelligence. It's just an aspect of the intelligence model like IQ or EQ etc.
I think it's a huge myth to think of athleticism as a talent and not a skill that can be trained. It's absolutely a skill - my wife was pretty uncoordinated when we met - she never really played much sport or did many outdoorsy activities. She just assumed she was uncoordinated, but after about a year of lifting weights, she's found that her balance and coordination have improved tremendously. She doesn't stumble when walking as much, she's better at doing things like catching stuff out of the air, and she's more aware of where her body is in space - she doesn't bump into things as much.
Frankly, this is true of literally every field. Like, imagine we all started in programming at age 10 and all received the same level of instruction- by age 20 there are again just huge, huge differences between where people are at ability-wise. It's unfair and doesn't fit into a lot of meritocratic 'just work hard and you'll end up at the top!' narratives (which are especially popular in the US), but it's sadly true
It may be explained by a dedication to a learning, by general abilities to learn, by nutrition, by inborn muscles properties (type I or type II), and probably by a dozen of other factors. I mean, what you'd said doesn't imply that differences in ability to play basketball are due to an amount of inborn athleticism received.
Those differences come from a lot of places, not least that the people who ended up on the better end of the stick almost certainly found every opportunity they could to play basketball outside of practice.
My sister and I both played sports and learned about computers in school. She spent lots of her spare time after school and on weekends shooting baskets in the driveway. I spent that time messing around on computers and taking things apart. Any guesses which of us ended up the better athlete and which the better engineer?
Do people really believe this? You can get pretty far with training but the top athletes have talent AND work hard.
Personally I was always one of the slowest, uncoordinated and weakest in any sport in my youth. When I was 16 I started martial arts and in a few years got myself from the bottom to someone who is generally regarded as pretty athletic. But I had to put in as much as work as other more talented guys who went on to win championship. Due to my lack of talent unfortunately championships were out of my reach but I am still happy with the improvement and it's probably one of the most important things I have done in my life.
https://www.litcharts.com/lit/the-man-who-mistook-his-wife-f...
It quit happening to me once the cat died.
Happened to me a couple times, but it's been like 15 years since.
I've dreamt I'd lost an arm before, only to wake up to find out I'd slept in a position that made the "missing" arm go totally numb.
https://www.painscience.com/articles/central-sensitization.p...
Physical therapy involves a lot of proprioception retraining that is lost due to injury, surgery or inactivity.
I'm curious if others can reproduce this for themselves?
My hypothesis is that the visual areas of the brain can get involved when the eyes are closed, and can pick up and interpret the proprioceptive information spatially. It may be that it's always happening, but that the "image" of one's hands is swamped by visual data when the eyes are open. Another hypothesis, I suppose, is that the visual expectation of the hands may be registering or, rather, its absence. You're "seeing" the expectation of the hands that should be there, but are blocked by your eyelids.
I should say that the sensation of seeing the hands is pretty fine, extending to the motions of the fingers. That said, it's easy enough to lose the image or forget it is there.
I closed my eyes in the dark and tried to touch my two index fingers together in random places instead of just pointing at my nose. Can confirm that I also "see" the position of hands and fingers.
I think what we "see" is mostly out brains doing spatial reasoning and using part of the same systems as used for visual perception.
Is there some way a human can be said to propriocept things that they neither saw nor touched?
So it’s more like a combination of sight and touch and forward modeling based on muscle input.
Imagine a robot arm. You have the armature and a beefy electric motor on it. Your task is to make it do some manipulation task. If all you can do is send voltage to the electric motor you will never succeed. You don't know where the arm is at any moment. But even if you would know where it started from you couldn't know how much it moved exactly just by knowing what voltage you sent to it. This is because minute variation in loading and tinny errors would accumulate into huge uncertainty in such an open-loop system. So basically you need something to close the loop. A rotational encoder on your robot arm, or muscle strain measurements on a living creature.
But just having the sensors is not enough. If you want to make the (robot or human) to touch a particular point in space you need to know how to turn the sensor readings into a transformation. I would be lying if I would tell you I know how exactly the human brain does this, but in robotics it's just a few transform matrixes multiplied together.
Suppose you were to anesthetize all the nerves leading to your skin. If you define touch in a way that's limited to skin interacting with stuff outside the body, then that would neutralize your sense of touch.
But according to the article, there are "piezo2" receptors embedded in muscle fibers. They can tell you how much the muscle is stretched or contracted. So even without using touch or sight, you could tell whether (say) your elbow is bent or straight based on information coming from your biceps and triceps muscles.
One could imagine a body that doesn't have this and works by some combination of dead reckoning (where the brain knows it pulled on the muscles this much, therefore the limb must have moved that much, and keeps a running total), sight, and cues from how the limbs are interacting with the outside world. But the article says it isn't just that. Instead, the brain is getting direct information from muscles.
You could, though, make a case that touch should be generalized and this should be included in it. The article says piezo2 receptors are used both in touch and in muscles. If you wanted, you could define touch to include sensations within the body, where this part of this muscle is touching this other part of the same muscle and feeling that.
Proprioception being an abstraction over touch and sight data that generates awareness of how your body is arranged in space is a sense in the same manner. And you can definitely get proprioception over more than your own body - partner dancers will quickly develop a felt sense of how their dance partner's body is moving, as well.
I think might other ways to approximate this. Try lying completely still in bed at night in the dark for 10 minutes or so... after a while you might have trouble knowing exactly how your limbs are positioned (unless, of course, you make a mental note of just how they were positioned when you first laid down, or kept your attention focused on that all along, but if you think of something else, then ten minutes later think about the position of your limbs, you might have trouble). The key in the above exercise is not feeling anything in your limbs that could give you a cluse as to where they're positioned. This makes me wonder if we need some kind of periodic kinesthetic or viseo-kinesthetic calibration to keep our sense of proprioception functioning well.
Psychedelic drugs could also impact our sense of proprioception, as they can just about everything else about our experience. Being in a floation/isolation tank could likewise affect it.
Something else I wonder about lack of proprioception is at all related to the problem some people have of telling right from left.
Proprioception is an interesting and exciting mental process that is important to artistic expression, human growth, mental development, and cultural communication.
Whew. The opera "Nixon in China" has an embedded ballet. The embedded ballet has the uncanny property that in a few minutes it retells the entire story of the opera.
Why is ballet so expressive? Why does the nation of Russia need ballet? Notice on youtube, the Russian dancers are extraordinary. A prima ballerina who came to New York, drew comments that "She dances in Russian." And the untutored viewer could see it too. The nation devotes considerable resources to the art.
What is happening when 1st through 5th graders in an American Elementary school run around and scream at the beginning of the school year? Were they running around to generate huge amounts of propriaceptive signals to the brain? Is the screaming part of the brain sending motor control signals every which way?
Finally, why do opera singers stand up to sing? Except when they are dying or portraying a special propriaceptive statement like kneeling (to pray or be beheaded).
On some long sidewalk (with no hazards on either side) or on a field, find any visible point 20-30 feet straight ahead of you, like a crack in the sidewalk or a leaf, whatever. Now look at it for just a moment (only takes a second or two to imprint its location) and close your eyes. Start walking towards that spot (no peeking), and stop when you think your foot is over the target. You will be shocked at how accurately you estimated the walking distance, and how your body very strongly senses when you've reached the spot. Almost 10 out of 10 times, my foot is perfectly centered over the target (modulo some lateral movement from not walking perfectly straight).
For me, I can somehow "physically" feel when it's close, I can feel when I'm over it, and I can feel when I've gone too far.
https://en.wikipedia.org/wiki/Body_transfer_illusion#Rubber_...
Of course, the room wasn’t empty and void other sounds, which may have helped me build a general sense of direction and thereby helped me.
There is no other sense involved, it is the same touch sense, but internal.