Feeling another’s pain

One traditional and difficult question in philosophy and metaphysics has been the knowledge we have of other minds. It is well known that for the founder of contemporary philosophy, the Frenchman René Descartes, non-human animals were probably what we would call today ‘robots’ or ‘zombies’: mere complex machines with no consciousness (in the sense of ‘awareness’), while the mind of other humans would be only indirectly knowable to us thanks to the work of language, through which one person can report his or her conscious states to others. Though today we are more sympathetic to the idea that animals (or at least those with a central nervous system) have a mind of their own, with emotions, feelings and even something like (primitive) thoughts, it is true, however, that the knowledge of the minds of other beings, either human or non-human, is problematic, perhaps not regarding the existence of those minds (after all, there are many other things we have scientific reasons to belief they exist, and that are as directly unobservable for you as my feelings and thoughts are), but regarding a stranger question, like what kind of ‘perception’, ‘awareness’, or ‘experience’ this knowledge of other minds can consist in. The already classical paper by philosopher Thomas Nagel, “What is it like to be a bat?”¹, pessimistically concluded just with the difficulty in explaining and getting precisely that kind of experience.

But in the last decades, progress in the field of neuroscience has allowed a development of new approaches to this problem. One example is the recent paper ² by Frédérique de Vignemont and Pierre Jacob, “What Is It like to Feel Another’s Pain?”. Drawing on experimental studies, these authors introduce first the notion of ‘vicarious’ feelings (we’ll follow them in talking mainly about ‘pains’), i.e., feelings or pains that I experience but that are not caused by a ‘direct’ physical process (like hurting my foot), but are caused instead by direct or indirect observation of your ‘direct’ pain. A ‘vicarious’ pain would, hence, be a ‘shared’ one, and, as we were saying, there are two kinds thereof: contagious pains and empathetic pains. In general, experiencing vicarious pain consist in imaginingbeing in pain. What is shared between two individuals, one of whom experiences vicarious pain as a result of her awareness of the other’s injury, depends on the former’s ability to imagine selective aspects of the latter’s painful experience, where ‘imagination’ can be divided into two different types, supposition-imagination (i.e., making conjectures, like ‘suppose that Mozart lived 80 years’) and simulation-imagination (i.e., imagining oneself doing something) ³; it is this second type of imagination what counts now.

Furthermore, some neuroscientific findings show that standard pain involves the joint activity of two dissociable neurological components: a sensory-discriminative component (helping to identify the damaged body part, and related to motor systems that induce behaviours leading to body protection) and an affective component (the one responsible of creating the unpleasantness associated to the damage); both systems can actually work separately, e.g., leading to cases in which one feels the pain but does not care ⁴.

What the neuroscientific evidence shows is that an experience of vicarious pain can be primarily generated by the selective activation of only one of the two components of standard pain: the sensory-discriminative or the affective component. In experiencing vicarious sensorimotor pain, one responds to the perception of another’s bodily part subjected to painful stimulation by imagining pain, that is, expecting specific sensorimotor consequences of pain, at the same location on one’s own body ⁵. On the other hand, other experimental evidence shows that the affective component of pain can be selectively activated when people are made aware of others’ painful experiences. For instance, when participants saw an arrow indicating that their partner was being inflicted a painful stimulus or when they saw a facial expression of pain, some experiments found that activation only in the affective component of pain, which was correlated with empathy personality traits, whereas no sensorimotor activity was found ^{6 7}.

On the basis of these and related findings, Vignemont and Jacob propose to distinguish between simulation-imagining the pain of other person in the sensory-motor way (what they call ‘contagious pain’, connected to the working of the mirror-neuron system), and simulation-imagining it in the affective way (what they call ‘empathetic pain’), though both kinds of ‘vicarious’ pains can be felt (or ‘modulated’) with different intensities, according to physical, social or emotional factors. One important difference between both types of vicarious feelings would be that they are respectively self-centered and other-regarding; the former depends more on the factors that can make you more ready to imagine yourself in the painful situation, whereas the latter depends more on your affective relation to the other person. One virtue of this model (one that, curiously for me, the authors don’t mention in their paper) is that it helps to explain why it seems so easy for human beings to find pleasurable the observation or even the production of pain in other people, something that could be more difficult to understand if the mechanism of vicaurious feelings were always of the contagious, mirroring type.