Specifically drawn to my attention lately has been the issue of spookiness. Every person knows a horse who is just a little spooky; you know, that horse that will take your head off with a tree branch at the sight of a plastic bag 60m down the trail? Or perhaps it's that horse who thinks that dandelions are simply the most terrifying plant to ever exist, and it must be avoided at all costs, no matter how drastic. Everyone knows a story or two about a time when some otherwise easy going horse frankly had a freakout.
So what causes this behavior? What causes our trusted steeds to lose their entire mentality in a swift second, and do anything possible in a pathetic effort to get out of the situation they are in? To understand equine behavior, we must look at where the behavior is most natural - in the wild. For example, a herd of mustangs are grazing happily on some delicious spring grass, when suddenly something catches the eye of the lead stallion. Don Juan's instincts to protect his herd kick in, and within an instant, the whole herd is on the move at Mach 1. What caused this reaction, that caused the whole herd to take off, rather than just Mister Don Juan alone? Firstly, horses are prey animals, and this means that they have a very large range of vision - more than 350 degrees, in fact. This means that horses can see a lot of things, all at the same time. Also note that due to the fact that they are prey animals, their eyes are on the sides of their head, opposed to humans (who are predators, technically, and have their eyes closer together to focus on prey). This causes horses to have two types of vision: monocular, and binocular. Monocular, or one sight picture, is how humans and predator animals see. It allows the two eyes to work together to focus on a prey, but it cuts the sight range in half. Binocular, or two sight pictures, is how many prey animals see things. Horses have considerably less accurate vision than humans, as most of the time they see in binocular vision due to the blind spot created directly in front and behind of them. Any disturbances in the sight picture may not be clear, causing a horse's prey animal instincts to kick in, rather than the logical thinking side.
So, you are asking yourself: "Why did the entire herd take off?" which brings me to my next point. Horses are herd animals. They have an established hierarchy, with a definite leader. If the leader takes off, the followers are, well, going to follow. Think about this in terms of your relationship with your horse. Think about the last time your horse took off on you; did he stop when you asked him to, or were you both so freaked out that you ended up on your head and he ended up in the neighbour's corn field huffing and puffing? If you answered yes to the first question, congratulations! You are most likely an effective leader for your two-animal herd. If you answered yes to the second question, listen up. Think about if Don Juan had just stayed put, even if said scary object approached the herd. The probability of the follower horses leaving the protection of the herd, despite the obvious approaching danger, is very slim. They trust that their leaders know what's going on, and if the lead horse books it to Timbuktu, you bet your sweet iron snaffle that they will follow. If your horse is the follower in your two-animal herd, the probability of him taking off and leaving you in the dust is much less likely than if he was the one expecting you to do the following. Given a mutually trusting relationship, your horse is much more likely to look to you and say, "is that dandelion really scary?" rather than, "that dandelion is scary! I'm out of here, because I don't think you'll protect me from it, so I won't protect you!".
The importance of having a mutually trusting relationship with your horse is the essential element in quick recovery from spooks, and essentially, causing your horse to think rather than act. Next time your horse tries to run you over because Sally's fly mask tumbled across the pasture in the same manner that a mountain lion would stalk your horse (because, you know, fly masks are terrifying), see if your horse calms down immediately after you reassure him that rabid fly masks are only going to attack the neighbours howling dog, or if he says forget this and leaves a nice Old Mac imprint on your face. Try to remember the natural instincts of horses, and be the lead mare/stallion in your herd of two (or more!). Proving to your horse that you can be trusted to get him out of any stupid situation he gets into is the only way to have an effective relationship with your horse. But you know, that's just my two cents.