The question most often asked by riders seems to be, "Why did he do that?" Actually, that question could be reasonably asked about everything a horse does, the good as well as the bad. Why does a horse do what he does?
Horses prefer to be comfortable. In fact, simply being comfortable is the primary reason for everything he does. To be as comfortable as a horse can get depends upon his ability to attain a dominant position within his herd. After all, the dominant horse doesn't have to fight for his food, is first in line for water, and has the best spot under the tree when it rains or gets too hot.. Talk about comfortable! A horse will do just about anything to work his way up the dominance ladder, and a smart horse learns very quickly what works to further his goals, and what doesn't. He will usually repeat what works.
While little wins along the way may not ultimately get him to the "top dog" position he seeks, each success brings with it a certain amount of comfort. It feels good , for even a fleeting moment, to be in charge. It feels good to win even smallest of battles. So, horses play little games and repeat the ones they win.
The most common game is "I Don't Want To". The rider asks his horse to, say, cross a small creek. The horse stops moving forward. Possibly he is concerned that the creek is not a wonderful place to put one's hooves, and he would be much more comfortable to just avoid the issue. Until something happens that makes him more uncomfortable than the thought of the creek, he has no reason to move forward. If he throws a little tizzy fit when the rider kicks him harder, and the rider backs off, he scores a point. If he gets his head turned around and can actually look away from the creek, he has won a major point. If the rider gives up and turns back or even moves to a different spot to cross the creek, the horse has won. You can bet that is a game he'll play again.
A favorite game is "Don't You Hit Me With That Whip!" It goes like this, Your horse starts out playing, "I Don't Want To" and you try to make him uncomfortable with a quick whack to the behind with a stout crop. His response is to buck. This is sometimes enough to make a rider rethink his approach to this game. If the whip gets put away, the horse has won the game, and has an edge at winning "I Don't Want To" as well.
Then, there is the "I am So Afraid" game. This one is tricky. Sometimes horses spook at things because they are truly afraid. Sometimes it is just a game. A good way to tell which is which is if the horse has seen the object before and not reacted to it, or the horse reacts differently to the same stimuli with different riders. If it really is a game, the horse scores big when you let him avoid the object, such as letting him cut wide around a corner or choosing a different trail. The horse can even get bonus points in this game when his behavior earns him a soothing voice and a gentle pat on the neck.
The cure for this behavior? Identify the games your horse plays, and change the rules. If he stops winning, he'll stop playing. Be careful you only set yourself up to play games that you know you can win, and if the contest is harder than you expected, stick it out until you have, indeed, won. That is the only way to be sure your horse won't play the game again, or if he does, he won't be so sure he can beat you. If you are trying to cross an obstacle, such as a creek, don't choose a dangerous crossing point, or a place where the approach leaves you no room to safely play the game. If you start to play and then determine that the creek is not really safe to cross here and turn your horse away, he will mark that down as a win for him. Choose your game sites carefully.
If it is getting late and you really need to be somewhere else, don't call it a draw and plan on returning to the issue on another day. Your horse will understand it as you giving up. He wins, even if he is asked to play the game again later. Be sure you give yourself all the time you need to play the game.
Some games get a little physical. After all, intimidation is one of the most effective tools horses have to win games against each other. If you cry uncle with the first spin or buck, your horse will discover intimidation works with you, too. Horses are smart enough to know the difference between you and your trainer. So, just because he stops the bucking game with your trainer doesn't mean he'll give up on it with you, too. The best way to insure that this game doesn't get repeated, is for you to win it, yourself.
Change the game. Make your horse feel comfortable when he does what you want him to do. Let him think he is winning, keep him happy by rewarding him for responding to your cues. Be careful not to bounce on the reins or slap his sides with legs when your horse is trying to behave, as this makes him uncomfortable and will encourage him to change his behavior, not repeat it. Make your horse uncomfortable enough to change his ways when his behavior calls for it, and do not be afraid to get physical. Be equally generous with a soothing voice and scratch on the neck to make your horse very comfortable with good behavior, and you and your horse will both come away winners.