On Hallucinating Pain

OK, so one more for the rode…

I was recently re-reading one of Ned Block’s papers (‘Bodily Sensations as an Obstacle for representationism’) where he denies that there is an appearance/reality distinction when it comes to pain. This is a commn view to have about pain (had for instance by Kripke in his argument against the Identity Theory). Here is what he says

 My color experience represents colors, or colorlike properties. (In speaking of colorlike properties, I am alluding to Sydney Shoemaker’s “phenomenal properties”  or “appearance properties” or Michael Thau’s nameless properties.) But, according to me, there is no obvious candidate for an objectively assessable property that bears to pain experience the same relation that color bears to color experience. But first, let us ask a prior question: what in the domain of pain corresponds to the tomato, namely, the thing that is red? Is it the chair leg on which I stub my toe (yet again), which could be said to have a painish or painy quality to it in virtue of its tendency to cause pain–experience in certain circumstances, just as the tomato causes the sensation of red in certain circumstances? Is it the stubbed toe itself, which we experience as aching, just as we experience the tomato as red? Or, given the fact of phantom-limb pain, is it the toeish part of the body image rather than the toe itself? None of these seems obviously better than the others.

Now if one has adopted a higher-order theory of consciousness one will think that there is indeed an appearance/reality distinction to be made here. Since it is the higher-order state, and only the higher-order state, that accounts for there being something that it is like to have a conscious pain it follows that there is the real possibility that one may misrepresent oneself as being in pain when one is not, or as not being in pain when one is.

So it is no suprise to find David Rosenthal saying stuff like this

Just as perceptual sensations make us aware of various physical objects and processes, so pains and other bodily sensations make us aware of certain conditions of our own bodies. In standard cases of feeling pain, we are aware of a bodily condition located where the pain seems phenomenologically to be located. It is, we say, the foot that hurts when we have the relevant pain. and in standard cases we describe teh bodily condition using qualitative words, such as painful, burning, stabbing, and so forth. Descartes’s famous Sixth Meditation appeal to phantom pains reminds us that pains are purely mental statess. But we need not, on that account, detach them from the bodily conditions they reveal in the standard, nonhallucinatory cases. (from Sensory Quality and the Relocation Story)

 So Rosenthal seems to be saying that it is bodily conditions that play the role that the tomatoe does and it is first-order states which constitute an awareness of those conditions which play the role that Block calls ‘representing color or colorlike properties’. If these are all distinct states, then we should expect for them to come apart.

 I have addressed the issue of unconscious pains in some previous posts. An unconscious pain, for Rosenthal and those like him, is a state that makes us conscious of some bodily condition and which will resemble and differ other pains states in ways that are homomorphic to the resembelances and differences between these bodily states. But what about the other case mentioned? Is it even possible to think that one is in pain and be wrong?

Rosenthal cites what he calls ‘the dental fear phenomenon’ as evidence for this claim. Here is what he says (in the same article as before)

Dental patients occasionally report pain when physiological factors make it clear that no pain could occur. The usual explanation is that fear and the non-painful sensation of vibration cause the patient to confabulate pain. When the patient learns this explanation, what it’s like for the patient no longer involves anything painful. But the patient’s memory of what it was like before learning the explanation remains unchanged. Even when what it’s like results from confabulation, it may be no less vivid and convincing than a nonconfabulatory case.

Now, I have always felt that this dental fear stuff was a really convincing way of showing that there really is a reality/appearance distinction for pains, but when I have tried to research this I have not been able to find very much on it (and Rosenthal offers no citations), but it does seem to be a reletively common phenomenon. Here is an excerpt from a paper on dental fear in children that tells a dentists how to deal with this

Problems that a dentist is convinced are associated with misinterpretation of pain may be addressed by explaining the gate theory of pain. A very basic explanation which is suitable for children as young as five is as follows. ‘You have lots of different types of telephone wires called nerves going from your mouth to your brain (touch appropriate body parts). Some of them carry “ouch!” messages and the others carry messages about touch (demonstrate) and hot and cold. The sleeping potion stops the ouch messages being sent, but not the touch and the hot and cold messages. So you will still know that I am touching the tooth and you will still feel the cold of the water. Your brain looks out for messages all the time. If you are convinced that it will hurt, it will. This is because if I make the ouch nerves go off to sleep and I touch you, a touch message gets sent. But your brain is looking for ouch messages and it says to itself, ‘There’s a message coming. It must be an ouch message.’ So you go ‘ouch’ and it hurts, but all I did was to touch you. It’s just that your brain was confused.’ (The language may, of course, be adjusted for older children.) If this fails to work, then active treatment should be stopped. (from Dental Fear in Children)

This is clearly a pain hallucination, as evidenced by the fact that the way they treat it is not with more medication, but with an explanation, pitched at the kids level, of why what they are fealing is not pain.

Now this is very different from what is called neuropathic pain, which is pain that is caused by a misinterpretation of an innocuous stimuli, like touch, or pains like phantom limb pain. This is the result of one kind of stimuli, for one reason or another, causing the bodily state that gives rise to the perception of pain.

Peripheral nociceptive fibers located in tissues and possibly in the nervi nervorum can become hyperexcitable by at least by 4 major mechanisms: a) nociceptor sensitization (“irritable nociceptors”); b) spontaneous ectopic activity; c) abnormal connections between peripheral fibers; and d) hypersensibility to catecholamines. This peripheral sensitization results in increased pain responses from noxious stimuli (primary hyperalgesia) and previously innocuous stimuli elicits pain (peripheral allodynia). Central nociceptive second order neurons in the spinal cord dorsal horn can also be sensitized when higher frequency inputs activate spinal interneurons. This results in the release of neuromodulators that activate glutamate receptors and voltage-gated calcium channels with a net effect of an increase of intracellular calcium that windup action potential discharges. Degeneration of peripheral nociceptive neurons may trigger changes in the properties of low-threshold sensitive neurons and axonal sprouting of the central processes of thesefibers that connect with central nociceptive interneurons. (from Neuropathic Pain Treatment: The Challenge

So it does look like we can distinguish the three states and that we do in fact find cases on one without the other.

Shesh! that turned out to be longer than i expected…but what the hell? I’m Outa Here!


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