Given the data, it’s likely that unconscious individuals (specifically, people in the minimally conscious state) do experience pain.
One reason why pain is difficult to study is that our subjective experience of pain (how it “feels” to feel pain) and physical manifestations of pain (having pain receptors and the brain’s recognition of pain) are different. After all, animals have pain receptors, but we don’t know if they “feel” pain the same way we do. Interestingly, consciousness (and self-awareness) was considered an important criterion for an organism to “feel” pain, which is why psychologists thought babies couldn’t feel any pain for a very long time. Imagine that! Given that, usually, we can only tell if someone is in pain and to what degree if we ask them, but what about when we’re unconscious?
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What does science say?
One way to investigate this idea is to ask caregivers or attenders who frequently deal with unconscious people. When medical doctors were asked, in a 2009 study, whether people in a vegetative or unconscious state could experience pain, 56% of them said yes, and 68% of paramedical caregivers also concurred. We can’t solely rely on their word though. It has been historically unwise to conclude from subjective second-hand experiences, even if they come from people we consider experts on the issue. After all, one’s mind can be deceptive. It’s possible to mistake any response as a response to pain. To avoid falling into the same trap, we must start by looking at the physiology of the brain and go from there.

Caption: Pain measurement scale generally used to study pain (notice that it depends on the subject themselves to rate their pain) (Photo Credit : Oxy_gen/Shutterstock)
How pain works in the brain
The brain is a complex organ, so not every process in the brain can be accounted for; the amount of information is simply too much to handle. To make things more manageable, psychologists tend to record which parts of the brain respond to particular stimuli and try to assign certain functions to the activated parts based on the stimulus administered. These tend to be generalizations, but they get the job done! Applying the same methodology, scientists qualitatively split the experience of pain by the brain into three parts: the “cognitive-evaluative”, the “motivational-affective”, and the “sensory-discriminative”, which in simpler terms means the emotional response we have to pain, how pain affects our motivation, and the brain’s sensory experience of pain, respectively. What we’re interested in is the brain’s experience of pain, and how it perceives it.

General Brain Anatomy (Photo Credit : Alexander_P/Shutterstock)
Conclusion
Given the data, it’s likely that unconscious individuals (specifically, people in the minimally conscious state) do experience pain. However, there still isn’t enough research being done on pain, at least, not enough to comfortably compare degrees of pain or even detect it in some cases. The study of the mechanism and experience of pain has wide-reaching consequences on how patients ought to be treated. If accurate estimates of the pain felt by unconscious patients aren’t made, doctors could risk over-administering or under-administering pain medication, both of which are problematic. Giving too little medication risks hurting the patient, whereas giving too much runs the risk of excessively sedating the patient and missing signs of returned cognition. A lot is riding on such research. Sam Harris, a popular psychologist, in his book “The Moral Landscape”, argues that secular moral objectivity can be achieved once we can detect and quantify pain (and pleasure) properly. The burden of all secular ethics, therefore, rests on the shoulders of Science!

Scales of Justice (Photo Credit : aerogondo2/Shutterstock)