”Agreement” where the head goes up and down means they want something. It can be accompanied by pawing as well.

“Uncertainty” and “Shock” are the same to different degrees. The horse is looking and thinking about something. Prick ears, quivering lip. The horse in “Shock” is more scared/interested in whatever he’s looking at. Whereas “Uncertainty” is trying to look away and go back to whatever he was doing but can’t quite.

“Disagreement” is likely a mare weaving. In horse herds there is always the stallion and the lead mare. The stallion travels in the front of the herd looking for dangers. The lead mare travels in the back keeping the herd together. Weaving is a herding technique used to push the most outside horses towards the middle. Mares in stalls will sometimes mimic that motion by swinging their heads back and forth. Usually due to boredom.