What triggers incident detection?

My problem today when my watch interpreted the end of my ride as an "incident" is that I was not wearing my reading glasses and all the text on my watch except "Incident detected" is in a tiny font and unreadable for me. I hit what I thought was the cancel button yet since my wife was called, and then needlessly worried, I must of hit the wrong button... I am disappointed that there seems no way to report false positives for incident detection. I interpret that to mean that Garmin will not get better as inferring when a real incident occurs. 

All the incidents listed here seem reasonable. However, I'm trying to understand why my VivoActive 3 sent an incident report today. I was hiking in a group, at a casual pace. When we stopped to take in the scenery my watch sent an incident report to my emergency contacts. I wasn't moving fast and I didn't stop abruptly. I track my walks/hikes about 3 times/week, since I got the watch 3 months ago, and have never had this happen. Why all of the sudden today? Very strange! 

Garmin should have incident detection on at all times. If something happens even when you're not in an activity. Apple watch even detects a car crash these days. Just a heads up Garmin Connect Mobile Android

I was out walking with a friend admiring Christmas light displays. We stopped for several minutes to watch a particularly spectacular one, with synchronized music and everything, and then we applauded when it ended.  As we walked away I realized that my wrist was buzzing, trying to find the phone I hadn't brought with me. So, angry geese and breathtaking light displays. (Or clapping hands?)