I'm really glad to see you made your first post. The other 600 or so must be illusions or something...
I have noticed the 'crowd mentality'. It'll pick you up in a second. For the opposite be at a ball game when the home team loses in the last second.
But I wonder if it reaches animals, too. That horse doesn't look any too pleased in that photo, perhaps it was just a temporary reaction what with added weight, a slap on the butt and all that. It almost must be a generally happy horse to be able to work in that sort of situation.
Thanks for a wonderful sunny and happy day.