Hold that pose
The next step is to lengthen the amount of time your horse looks away. You do not want a horse that looks away, and then looks right back. Your horse should look away and hold his head still until he hears the bridge. This stage requires some finesse on your part and must be done gradually.
Once your horse understands the task, draw out the time before you bridge by about one second. If this works, gradually go for another second over the next few sessions, and so on. Your horse will probably perform the behavior and then bring his head back to you. Wait him out until he moves his head away again, then bridge.
Learn to predict when he will bring his head back and bridge before it happens in order to avoid training a "double-take." You do not want the horse to repeatedly swing his head back and forth. Once you are getting longer "holds," extend the time even more before reinforcing, but also bridge some shorter ones in between.
Add Variety, Add Challenge
Okay, let's say your horse gets it by now. He is holding his head where you want it for several seconds. Now it is time to add variety. Change locations by orienting him in different directions. This is essential so that the behavior does not become context-specific. In other words, the horse learns to perform the behavior anywhere, anytime, not just when facing the waterer in the corner of the stall at sunrise.
Along the same lines, once the behavior is learned on one side, change to the other side so that the horse responds to you wherever you are. Your horse should require less training time on the second side, but be sure to train it just as perfectly as the first.
During the initial stages you must bridge and reinforce frequently, but over time you will include a variable reinforcement schedule (VRS) and start to shape behaviors. With shaping, you only reinforce the better responses (such as when he gives you a better head position). With a variable reinforcement schedule, you only give food at certain, unpredictable intervals. Horses, as well as other animals, try harder when a VRS is used. This is also true for humans-just look at the popularity of slot machines.
Fading Out Food
Now, no one wants to carry food around at all times while interacting with horses. Therefore, once a given behavior is learned, you will start to fade out food so that you only give it occasionally, or only at the end of a session. The bridge will become reinforcing in itself. Other reinforcers, such as stroking, can also be added.
Eventually, your horse's manners should become so perfect that he will hold his head and body still even when you have a full bucket of grain and a big flake of hay, or whether you are holding up whole carrots right next to him. Picture yourself walking into the middle of a herd, carrying hay and a grain bucket, and not getting mugged!
Target practice
Once your horse understands how to be polite at all times, it is then time to add to his repertoire. You can use positive reinforcement to teach your horse to respond to targets, which are handheld or stationary items that serve as an object of focus.
Back in the days when I was doing cognition research with seals and sea lions, I used targets to have these animals stay in one location, place their noses on my hand, follow me, and perform a number of behaviors. Years later, when I tried target training with horses, I found they responded just as easily.
I use targets to train horses to do many different things such as: load into and out of a trailer at liberty; stand in one spot while untied (especially useful if you want your horse to stay in one area of the stall while you work in another); raise, lower and flex their heads to each side; cross obstacles such as creeks or logs; become braver around unusual objects or events; and for fun stuff like jumping, rolling balls, chasing Frisbees, and twirling ropes.
Most people do not want unsafe horses, and I am no exception. But one was donated to the Equine Research Foundation a few years ago and she came with all sorts of issues. When Callie first arrived, we couldn't stand near her head. She'd swing it around and nearly knock us over. The hind end wasn't any better due to flying hooves. Things got even more interesting in the saddle when she would toss her head or buck. And, of course, she didn't know how to do anything slowly. However, within about two weeks, she turned into one of the calmest, safest, most well-behaved horses I have ever encountered. All it took was ground work, bonding, and positive reinforcement.
With positive reinforcement and a strong human/horse bond-if you can imagine it, you can train your horse to do it.
