[otakucode]

I originally read about the phenomenon years ago in a (audio)book, but I cannot recall which one. It may have been one of Oliver Sacks' books, or part of a course from The Teaching Company or the Great Courses Plus. They discussed related research that claimed to have found strong evidence for depression in patients paralyzed from the neck down which was greater than the life changes and such could account for. I was never clear on how they could possibly manage to separate the things to be able to make such a claim and the facial paralysis emotional involvement seemed to make much more sense. There is a great deal of evidence already linking facial involvement to emotion, such as the classic study where participants held a pencil in their teeth, which causes an involuntary 'smile', lessening the negative emotional response when watching sad videos, so it seemed to be reasonable.

It's not that the people become un-empathetic, but literally when shown a photograph of a face expressing the emotion of anger, they can not identify that it is the emotion being displayed. That is the most extreme extent that takes the longest to manifest as I understand it. If a person told them "I am angry" or there were other outward displays (raised voice, etc), I don't doubt they would deal with it appropriately. Issues with recognizing emotions in others based on facial expressions are not all that rare. It is very commonly found in men who abuse others that they are incapable of recognizing the expression of fear in the face of those they are abusing.

I managed to find one related study that you might find interesting reading, though I hope to find better resources eventually: https://jamanetwork.com/journals/jamafacialplasticsurgery/fu...

My personal view is that this paper is probably closest to being correct about the nature of emotion and the body: https://www.cell.com/trends/cognitive-sciences/fulltext/S136...