I don't think this is just related to the discipline skill. I just got through a siege, followed by a tantrum spiral that dropped me from over 100 dwarves to just 11. The siege only killed 4 dwarves, but that was enough to trigger the spiral. The place was a mess, with goblin and troll corpses outside and in my trap corridor, and dwarf corpses all over the place inside.
After it finally died down and dwarves were getting to work building coffins and filling them, a wave of migrants arrived. The surviving dwarves were going about their business as if the red on the walls was just paint, and the corpses just part of the furniture, but the new arrivals were cancelling jobs right and left, "Horrified" or "Emotional shock".
Actually, after examining the announcements, one newcomer was horrified 4 times, and all the other cancellations were emotional shock.
I used Dwarf Therapist (DT) to sort by migration wave, and checked discipline, and some of the survivors still have 0 discipline, yet are having no problems, while a few of the migrants already had discipline of 1, and are being horrifically shocked. So there's something more than just discipline at work here.
I've gone through in DT and grouped by migration wave, then sorted by various traits to see what correlations I can find. One thing i also did was filter out those who are resting. They were injured during the spiral and have been sitting in their rooms or the hospital, so probably haven't seen as much carnage as the other survivors.
I started out by tallying up who got what cancels. Since the migration wave arrived, 2 survivors each had 2 emotional shocks (hereafter: ES). 3 of the newcomers have had no cancels, the rest had 1, 2 or 3 ES. Only the one dwarf was ever horrified, and he was horrified (hereafter: H) 4 times (and 1 ES).
The one who was horrified 4 times is also the one with the lowest bravery trait, at just 36 (Is somewhat fearful in the face of imminent danger). Also consider that it's very possible that being horrified might raise whatever trait makes one vulnerable to it, so he might have started even lower. The next lowest was a 41 (no text for this), who was not ever horrified.
I don't see any obvious correlation for the ones who were ESed. It's possible that the trait that cause it was sufficiently raised that no correlation shows up now.
Confidence looks close at first glance, with most of those having ESes being below 50. But one who had an ES has a confidence of 60, and the dwarf with the lowest confidence value, 28 (Sometimes acts with little determination and confidence) is a new migrant and didn't have an ES. BTW the confidence of 60 is the same one who had the lowest bravery - maybe being horrified and surviving 4 times boosted his confidence?
Hmm, after filtering out the resting dwarves, I just realized that the survivors with 0 discipline are all resting, so that's why they aren't being horrified or ESed. Of those who were ESed, most do have 0 discipline, but one newcomer who ESed 1 time has a discipline of 1 (and 32% of the way to 2). That's the fellow who was also horrified 4 times, so maybe he started out below 1? The 2 survivors who each ESed twice since the migrant arrived have discipline values of 2 and 3 though, so there must be something else involved. There are survivors with discipline of just 1 who have been fine.
This is definitely something that needs more ‼SCIENCE‼ done. One needs to keep track of each dwarf's traits, skills, and attributes before and after each H or ES event and see what changes. Unfortunately, with the help of the new migrants, all the corpses in my fort have been either properly buried or dumped in the refuse pile outside, so the next wave of migrants won't make good test subjects. I guess I could try restoring from my last seasonal backup, but that was over a month before the migrants arrived, and I don't really want to replay that particular month. It wasn't pretty.
There also needs to be similar study of H and ES during combat. Parts of my siege looked like something out of the old TV serise, F-Troop "Where Indian fights are colorful sights and nobody takes a lickin', cause paleface and redskin both turn chicken!" At one point I had a single hammerdwarf stuck outside and about a dozen trolls were coming at him. Suddenly all but one Troll turned and ran away in terror. My guy went into a trance, danced with the Troll for a while until 8 or so goblins showed up. Then he proceeded to dance around, jumping away from blows while knocking out one opponent at a time, leaving a trail of unconscious goblins (and 1 troll). Being a hammerdwarf, of course he didn't actually kill any of them. After he knocked out the last one, he came out of his trance and immediately went into emotional shock and just stood there until a goblin crossbowman walked up to him and swing its crossbow at him. I then unleashed a squad of dwarves, and they rushed around the corner, saw the carnage-strewn field, and half of them were immediately hors de combat with shock. The others would rush up, smash in the head of one unconscious invader, then apparently were completely shocked at having killed someone and stood there thinking how truely horrifying it was. From here on out, I maybe had 2 or 3 effective troops at any given time, out of 15 or so in my military. The rest were just standing around in shock and/or horror.
We've got to find a way to emotionally prepare troops for combat.
Sorry for going so long.
Keith