I've persued an interest in horse training for some years, sence the late 80's i guess when I first discovered i was interested in horses. So I've tried to learn everything posible about them.
I obtained information from every trainer I could get info from without spending too much, going to clinics and demo's all over the place, always choosing the trainers seminars at horse fairs. So it seems the best of what it all boils down to is;
Horses have a herd social system of their own, and they have the knowlege of how it works kind of built in like instinct, (although the practice of it can get rusty when they don't grow up in a herd, but it's still there)
When we get near a horse for the most part we are stepping into their herd social system, (herd of 2 when it's just one horse we're dealing with) and we are going to be treated just like another horse. In their system horse no 1 tells horse no 2 and those on down what to do and not do, and 2 tells 3+ what to do, etc. In order for me to get my horse to do what I want willingly, I need to be seen as no 1 herd boss by him/her. Also every horse in the herd knows automatically ya don't kick the leader, ya don't bite the leader, ya stay out of leaders space, and so on. (unless they want to pick a fight with the herd leader and hope to become herd boss themselves)
Sence horses "talk" in body language, I need to educate myself to perform the body language of herd boss every time I get near a horse.
That language may be as suttle as a look or a slight move, or it could include running faster, biting harder, or kicking harder, than they can.
But some of those things I can't do and survive. That's where a round pen and a few tools come in handy.
Basicly it's a case of who makes who move. When I make horse move I'm boss, when horse makes me move then he's boss.
In practice, using herd sycology on a horse in a RP requires some good ability to read horse attatudes, those who can't read horses may have trouble responding to the horses messages and can not get accomplished what's desired. Horse reading ability is obtained by spending lots of time watching horses, and observing them closely in their actions and reaction among each other and their people handlers.
There are a few techniques that can be used in round pen work to urge a horse into making the decision to accept me as their herd leader, but those techniques can lead to trouble occasionally if used a bit too hard or soon. Hence the need for reading the horses attatudes and adjusting intensity of work accordingly.
Transitions are what pushes the horse mentally into making decisions. Doing too many transitions too soon or too rapidly might produce a blowup, however on the other hand when it's time for a decision to accept my leadership, they can be pushed into making it by increasing the rapidity of transitions.
One time I saw a mare training her foal using that exact technique. She was teaching her young one to stay with her according to the owner. (yah, that's where the idea came from)
If this technique is used properly and combined with the despooking process it can lead to a horse that wants to stay with me no matter what happens. A horse that automatically flees from new surprises can be reprogrammed to look to me for assurance of safety instead of running from the supposed danger.
Many of the NH training teachers out there arn't explaining the reasons behind what they teach very well, they're teaching a system of training moves without getting across an understanding of the whys behind it. When you know why it works and how to make it work, (just like the horses make it work on each other) then the rest becomes easy.