How much pressure would you say is in a pull? How long would you say is a hold? And how is that different from a “signal”?
You don’t have to actually pull to be pressuring a horse.
You hold, you wait, until the horse gives. At the very, very beginning, you’re going to have to reward the slightest try, which might mean you have the horse on a halter, and there is perhaps 20 pounds of pressure on the lead rope (which to be the ‘right’ amount of pressure, is going to be exactly the same pressure it takes to meet the horse at what pressure he has given against you, because you can’t simply overpower him if you’re going to teach him something about giving, rather than ‘I can overpower you so resistance is futile’), and the horse goes from 20 pounds to 19.9 pounds.
So you release.
And you take a few deep breaths, you let that process in his computer and yours, and a minute or 20 minutes or an hour later, or maybe tomorrow (depending on the situation), you present pressure on the halter lead again.
Let’s assume the horse gives you 20 pounds again as what it takes to meet him at the right place.
He’ll probably give sooner, and more, like to 10 pounds or 5 pounds. So you release, and let that soak.
And you continue to present that, and the horse starts giving right over to zero.
The next thing that happens, is the horse looks for ‘what happens before what happens, happens’ and you take a feel of the lead rope, and the horse prepares to give to pressure, and in fact gives before you put physical pressure on the rope.
The next job is to get the horse giving not to a physical, take-the-pressure-off-the-rope give, but to get the horse to give sideways, via the hindquarters stepping over or the jaw tucking, in a way that the horse releases a brace.
You can do that in a sidepull or snaffle bit, and start with a physical pull.
Or, once the horse really understands, you can put a bit of ‘ask’ or signal on the rein (sidepull, snaffle, bosal, anything) without a physical pull, and address the horse’s brace THERE, and wait for him to give.
You have to address the horse’s MIND, you are asking him to GIVE to you, and that can be done without physical pressure.
This is what Martin is up to in the video portion you posted, he does have some physical pressure on the bosal but it is not a pull on the rein. Once his horse gets to where he gives without physically putting pressure on the bosal, he has the horse on a feel…so he’s done with that and goes on to something else.
For more…
Here, Buck discusses lateral flexion, and how we don’t want the horse tipping its nose out of plumb:
http://www.youtube.com/watch?v=WiTFFei1tTo
There is LOTS more here, from Dr. Deb Bennett at the George Morris clinic last January (2013). You have to search through before you get to the streaming videos, they’re pretty long but quite valuable:
http://www.usefnetwork.com/featured/2013GeorgeMorris/