Why is proprioception not considered one of the main senses?

[ThOrNe]

How many actual senses do you think we have? Cuz I think of hearing as just very sensitive touch and wonder how we sometimes know how something tastes from its odor or visa-versa...

 

[Another God]

well there are only five actual tastes (Sweat sour etc), and the rest of the tastes we experience are part of the smell sense.

Personally, I believe the sense of balance should be included.

 

[Mentat]

Originally posted by Another God
well there are only five actual tastes (Sweat sour etc), and the rest of the tastes we experience are part of the smell sense.

Personally, I believe the sense of balance should be included.

But the sense of balance is really just part of the "touch" sense, since a feeling of being inbalanced is just the feeling of the fluid inside a certain compartment in your ears (can't, for the life of me, think of the name) washing up against tiny hairs...this is basically what I've read on the subject.

Anyway, as to the original question of the thread, Aristotle (at least, I think it was Aristotle ), came up with a lot of generalizations in his writings, and this was one of them. He generalized all of the senses into five basic sets.

 

[hypnagogue]

There has been some good discussion on this topic in this thread in Skepticism and Debunking:

https://www.physicsforums.com/showthread.php?s=&threadid=7888

Ironically, SelfAdjoint had this to say in that very thread:

First of all, that we have only five senses is folklore, scientists have identified others - post a query on the Biology board and someone will be sure to have a list. One I remember is proprioception, the sense of where your body is, and how its parts are arranged. This is the sense that you use when working on a screw or something like that behind a barrier so that you can't see it. There's nothing mystical about it.

There are definitely more than 5 modes of perception that could rightfully be called "senses." A quick google search didn't give any definitive answers, but here is a (bit lengthy) excerpt from http://www.informationheadquarters.com/Autism/Sense.shtml:

Definition of "sense"

A broadly acceptable definition of a sense would be "a system that consists of a sensory cell type (or group of cell types) that respond to a specific kind of physical energy, and that correspond to a defined region (or group of regions) within the brain where the signals are received and interpreted". Where disputes arise is with regard to the exact classification of the various cell types and their mapping to regions of the brain.

There is no firm agreement amongst neurologists as to exactly how many
senses there are; the disagreements stemming from a lack of a common
consensus as to what the precise definition of a sense actually is. Although schoolchildren are routinely taught that there are five senses (sight, hearing, touch, smell, taste; a classification first devised by Aristotle), there is no doubt that this is most certainly in error. Regardless of the dispute, it is agreed that there are at least nine different senses in humans, and a minimum of two more observed in other organisms.

List of senses

Using this definition several senses can be identified. This list begins with those five senses defined by Aristotle and hence probably most familiar to the reader.

Seeing or vision describes the ability to detect light and interpret it as "sight". There is disagreement as to whether or not this constitutes one, two or even three distinct senses. Neuroanatomists generally regard it as two senses, given that different receptors are responsible for the perception of colour (the frequency of light) and brightness (the energy of light). Some argue that the perception of depth also constitutes a sense, but it is generally regarded that this is really a cognitive (that is, post-sensory) function derived from having stereoscopic vision (two eyes) and is not a sensory perception as such.

Hearing or audition is the sense of sound perception and results from tiny hair fibres in the inner ear detecting the motion of atmospheric particles within (at best) a range of 20 to 20000 Hz. Sound can also be detected as vibration by tactition. Lower and higher frequencies than can be heard are detected this way only.

Taste or gustation is one of the two "chemical" senses. It is well-known that there are at least four types of taste "bud" (receptor) and hence, as should now be expected, there are anatomists who argue that these in fact constitute four or more different senses, given that each receptor conveys information to a slightly different region of the brain.

The four well-known receptors detect sweet, salt, sour, and bitter, although the receptors for sweet and bitter have not been conclusively identified. A fifth receptor, for a sensation called "umami", was first theorized in 1908 and its existence confirmed in 2000. The umami receptor detects the amino acid glutamate, a flavor commonly found in meat, and in artificial
flavourings such as monosodium glutamate.

Smell or olfaction is the other "chemical" sense. Olfactory neurons differ from most other neurons in that they die and regenerate on a regular basis.

The remaining senses can be considered types of physical feeling.

Tactition is the sense of pressure perception.

Thermoception is the sense of heat and the absence of heat (cold). It is also the first of the group of senses not identified explicitly by
Aristotle. Again there is some disagreement about how many senses this
actually represents--the thermoceptors in the skin are quite different from the homeostatic thermoceptors which provide feedback on internal body temperature. How warm or cold something feels does not only depend on temperature, but also on specific heat capacity and heat conductance; e.g., warm metal feels warmer than warm wood, and cold metal feels colder than cold wood, because metal has a higher thermal conductivity than wood. Wind feels cold because of the heat withdrawn for evaporation of sweat or other moisture, and because an isolating layer of warm air around the body blows
away; however, in the case of hot air, wind makes it feel hotter, for a similar reason as the latter.

Nociception is the perception of pain. It can be classified as from one to three senses, depending on the classification method. The three types of pain receptors are cutaneous (skin), somatic (joints and bones) and visceral (body organs).

Equilibrioception is the perception of balance and is related to cavities containing fluid in the inner ear. There is some disagreement as to whether or not this also includes the sense of "direction" or orientation. However, as with depth perception earlier, it is generally regarded that "direction" is a post-sensory cognitive awareness.

Proprioception is the perception of body awareness and is a sense that
people rely on enormously, yet are frequently not aware of. More easily demonstrated than explained, proprioception is the "unconscious" awareness of where the various regions of the body are located at anyone time. (This can be demonstrated by anyone closing their eyes and waving their hand around. Assuming proper proprioceptive function, at no time will the person lose awareness of where the hand actually is, even though it is not being detected by any of the other senses).

Based on this outline and depending on the chosen method of classification, somewhere between 9 and 21 human senses have been identified. Additionally there are some other candidate physiological experiences which may or may not fall within the above classification, for example the sensory awareness of hunger and thirst.

I think what we can take from this is that it's a bit arbitrary where we draw the line between senses (ie regarding taste as one sense or four), but nonetheless there are definitely senses that are not accounted for by the typically cited five.

I don't think it's appropriate to regard equilibrioception (sense of balance) as merely a certain kind of tactile sense, as has been suggested, since if we accept this claim then we should also regard hearing as a kind of tactile sense.

 

[BoulderHead]

Does a sense of loss count?

 

[Mentat]

hypnagogue, thanks for the reference (to the other thread). However, I disagree that these generalizations (and that's what they were supposed to be ITFP) are inadequate. Correct me if I'm wrong, but isn't proprioception only possible after having first used the senses to get a "feel" for where things are "supposed to be"?

Others have mentioned the "sense of time", but that is part of the circadian rythm, which is a secretion of hormones, which stimulate our inner sense of feeling, which is one of the five generalizations.

 

[Mentat]

Originally posted by BoulderHead
Does a sense of loss count?

Do you mean that you've lost count of the senses, or that you've lost sense of counting?

 

[Another God]

Maybe he has count'loss sense?

 

[hypnagogue]

Originally posted by Mentat
hypnagogue, thanks for the reference (to the other thread). However, I disagree that these generalizations (and that's what they were supposed to be ITFP) are inadequate. Correct me if I'm wrong, but isn't proprioception only possible after having first used the senses to get a "feel" for where things are "supposed to be"?

I'm not sure about that one. Consider someone like an acrobat or an olympic diver, however-- once they are in the air, things move too quickly to rely on vision to get an accurate feel for their bodily orientation in space at any particular time. Any prior stable sense of orientation from the typical 5 senses is almost definitely lost, yet these people have amazing awareness of their orientations in space nonetheless. I think this is good evidence that proprioception should be called a sense in its own right, not something derived from the other 5.

 

[Mentat]

Originally posted by hypnagogue
I'm not sure about that one. Consider someone like an acrobat or an olympic diver, however-- once they are in the air, things move too quickly to rely on vision to get an accurate feel for their bodily orientation in space at any particular time. Any prior stable sense of orientation from the typical 5 senses is almost definitely lost, yet these people have amazing awareness of their orientations in space nonetheless. I think this is good evidence that proprioception should be called a sense in its own right, not something derived from the other 5.

But these people are professionals, who have honed these abilities through training and constant practice. They, basically, evolved these talents, from having done it wrong so many times. I would say that this is part of what is usually referred to as "muscle memory", and...well...I guess that fits in with the "feeling sense" still, right?

 

[hypnagogue]

Originally posted by Mentat
But these people are professionals, who have honed these abilities through training and constant practice. They, basically, evolved these talents, from having done it wrong so many times. I would say that this is part of what is usually referred to as "muscle memory", and...well...I guess that fits in with the "feeling sense" still, right?

No doubt that an acrobat must train extensively in order to perform the feats s/he does. But any musician not born with perfect pitch must also train extensively in order to hone in on an accurate sense of pitch. So the fact that acrobats must train to develop their skills does not automatically rule out proprioception as a sense in its own right.

I'm sure muscle memory plays a part, but I would think that muscle memory only applies to repetitive motions, and cannot account for novel exhibitions of bodily awareness. For instance, if a basketball player makes an incredibly athletic layup around the defense, then s/he almost certainly is not relying completely on muscle memory, since this specific feat has never been performed by him/her before. It makes more sense to assume a dynamic sense of bodily orientation that applies to novel situations, and this is precisely what proprioception is.

 

[wasteofo2]

Originally posted by Mentat
But these people are professionals, who have honed these abilities through training and constant practice. They, basically, evolved these talents, from having done it wrong so many times. I would say that this is part of what is usually referred to as "muscle memory", and...well...I guess that fits in with the "feeling sense" still, right?

I have to agree Hypnagogue on this topic.

I play basketball. Certainly there is some sense of muscle memory in the individual actions inherent in any athletic event(bouncing the ball so it doesn't hit your foot and comes back to your hand in a way which you have control over it, jumping and releasing the ball at the correct moment), but there is no muscle memory for a series of improvisations, I'd describe it more closesly as a learned reflex and a subconscious awareness of my body and how it moves. I don't actually think "My defender's hand is coming towards the ball, so i should move the ball to my left hand by bouncing it at an angle so that I will be able to both avoid my defenders hand and go around him while also making it bounce up into my left hand so i can again bounce it at the floor so it will come to the spot my hand will be after I run etc." but merely do it. Infact, often when I complete a series of improvisational actions, I do not even remember what I did, even though I may have never done anything like it before.

 

[Mentat]

Originally posted by hypnagogue
No doubt that an acrobat must train extensively in order to perform the feats s/he does. But any musician not born with perfect pitch must also train extensively in order to hone in on an accurate sense of pitch. So the fact that acrobats must train to develop their skills does not automatically rule out proprioception as a sense in its own right.

Oh, indeed not, but it does make proprioception seem like something of an unnecessary addition, doesn't it?

I'm sure muscle memory plays a part, but I would think that muscle memory only applies to repetitive motions, and cannot account for novel exhibitions of bodily awareness. For instance, if a basketball player makes an incredibly athletic layup around the defense, then s/he almost certainly is not relying completely on muscle memory, since this specific feat has never been performed by him/her before.

Hmm...but wouldn't feats very much like this have been performed, thus making the probability of her/his doing it correctly that much higher (though not as high as the probability of doing something that s/he's done hundreds of times before)?

It makes more sense to assume a dynamic sense of bodily orientation that applies to novel situations, and this is precisely what proprioception is.

Maybe...I'm not really sure either way.

 

[hypnagogue]

Originally posted by Mentat
Oh, indeed not, but it does make proprioception seem like something of an unnecessary addition, doesn't it?

I don't think so. I think human perception is better explained with proprioception. OR doesn't apply as a criterion for judgment of two separate theories if one theory explains things better than the other.

Hmm...but wouldn't feats very much like this have been performed, thus making the probability of her/his doing it correctly that much higher (though not as high as the probability of doing something that s/he's done hundreds of times before)?

Possibly, but in sports (especially basketball) you see all sorts of movements that are so novel that it makes more sense to assume a dynamic sense of bodily orientation to explain them than a framework that depends on past sensations being extrapolated into a future scenario where they no longer apply.

Your standpoint-- as far as muscle memory is concerned-- to me seems somewhat reminiscent of classical behaviorism. But we already know that classical behaviorism cannot explain novel behaviors.

 

[Mentat]

Originally posted by hypnagogue
I don't think so. I think human perception is better explained with proprioception. OR doesn't apply as a criterion for judgment of two separate theories if one theory explains things better than the other.

If it explains it better only after having added the new assumption, then isn't it considered an ad hoc type argument?

Besides, what would be the "carrier" or (perhaps) organ that produces proprioception.

Possibly, but in sports (especially basketball) you see all sorts of movements that are so novel that it makes more sense to assume a dynamic sense of bodily orientation to explain them than a framework that depends on past sensations being extrapolated into a future scenario where they no longer apply.

Your standpoint-- as far as muscle memory is concerned-- to me seems somewhat reminiscent of classical behaviorism. But we already know that classical behaviorism cannot explain novel behaviors.

True enough. However, you still have the problem of what exactly facilitates proprioception. When you find it, it will probably be assimilated into one of the five main senses anyway . Seriously, I can't see what it could possibly be that isn't covered by one of - or a combination of - the five main senses.

 

[zoobyshoe]

Originally posted by Mentat Besides, what would be the "carrier" or (perhaps) organ that produces proprioception.

Proprioceptors

True enough. However, you still have the problem of what exactly facilitates proprioception. When you find it, it will probably be assimilated into one of the five main senses anyway . Seriously, I can't see what it could possibly be that isn't covered by one of - or a combination of - the five main senses.

I'm not sure you're understanding what proprioception actually is.
It is an internal sence. It is how you know what position your body and limbs are in even when you're not looking at them.

The "medium" of proprioception is nerves that terminate in proprioceptors - these might be likened to pain receptors or pressure receptors except they specifically transmit information about position to the brain.

If your sense of proprioception cut out for some reason it would devestate your life. You would not be able to move any part of your body from one position to another without looking directly at it and doing a lot of trial and error fumbling with muscle control. No other sense we have could be taken advantage of to fill in the gap left by the loss of proprioception.

Oliver Sacks told the story of a woman who lost her sense of proprioception in his book The Man Who Mistook His Wife For A Hat. The chapter is called The Disembodied Lady.

Proprioception is as important as any of the classic five sences. To our great luck it almost never fails, but for the same reason most people live and die not even realizing they have such a sence.

I believe balance and proprioception are separate sences in their own right and deserve to become number six and seven in the list of sences.