Understanding how a horse thinks is the foundation for all my bombproofing strategies. If you understand your horse's motivation, it will be easier to comprehend why certain training methods are effective, while others are not. All horses have the same basic instincts, though they undeniably vary in intensity with each individual.
Imagine you are hacking toward your friend's house, preoccupied with removing bits of hay from your gloves, when your horse spots the tent a neighbor's child has set up. It's windy, and the roof of the tent billows. Your horse jolts to a stop, and he wheels and launches himself in the opposite direction. As you struggle to haul him back under control, thoughts roll through your mind. Stupid horse! He nearly ran us right into that tree. He has the brain of a hamster.
Your horse, of course, considers this scenario in another way. He saw the tent shuddering, waiting to spring toward him and swallow him whole, and supposes it was his quick reaction that saved his skin (since you obviously were dozing and failed to note the danger). You and your horse are both doing what comes naturally: You're thinking like a human being, and he's thinking like a horse. The point? He's not going to start thinking like a human being -- not now, not next week, not ever.
The Comfort Zone
When your horse lopes around the same small course of fences that he has negotiated a hundred times, he's well within his comfort zone. On the other hand, when a green 3-year-old is asked to leap a log into water, he has been pushed far out of his comfort zone. As far as he's concerned, you've asked him to do something impossible, and he doesn't like it.
Whenever you train your horse to another level by introducing a new stimulus, you need to find the boundary of his comfort zone, and push him to stretch a bit beyond it. You need to "tread the line" and find the right balance just beyond the place where he remains relaxed but before the place where he is totally uncomfortable. This "breaching" of the boundary of his comfort zone is what gets him closer to accepting a new stimulus.
But you'll have to strike a balance: Challenge a horse too little or too much and he won't learn anything. Deciding on the level of stimulus is a very personal thing, unique to each animal and circumstance. What constitutes a minor test of nerve and obedience for one horse may be an insurmountable obstacle to the next. It depends on the horse's natural aptitude, coupled with his experience level and prior training.
The comfort zone boundary can also be physically established by distancing a horse from a threat. Usually, when a horse flees, he assesses the risk by glancing backward while he sprints. Eventually, he stops galloping. He's calculated that he's out of danger. He may have traveled 20 feet or 100 yards, but right then, he has reached his comfort zone.
Asking the Right Questions
Imagine a noisy machine, like a bulldozer. If it is clanking around right next to your horse, the noise will probably upset him. But will he flinch at the sound when it's several blocks away? Probably not. Somewhere in between these extremes is the boundary of your horse's comfort zone. When you work to gradually increase the size of the comfort zone of your horse to anything--from sudden loud noises, to rocks on the ground, to cars whizzing by--you are sensory training your horse.
Think about this concept and try to imagine how things appear to your horse. When you decide which route to take in crossing a ditch, consider whether your horse can tackle a steep bank, or will a flat, open crossing amply challenge him? The idea is to ask questions, but only ones that your horse can reasonably answer successfully.
So how do you decide what is an appropriate question for your horse? The key to your success is that you must have a probable positive outcome. A positive outcome first means that you can actually get your horse to do what you ask, and second, that the experience will build confidence in him. If you have reasonable expectations of meeting these criteria, then the task you are asking is appropriate.
In my clinics, I often ask horses to cross a mattress. Chances are, this pushes the horse well out of his comfort zone. He will almost certainly be at least mildly alarmed, and he may well back up, spin, or try to bolt and leave entirely. He may even rear. However, in a controlled, clinic environment, one way or another, it's a pretty sure bet that eventually, the animal will see things my way and attempt the crossing.