What is the approach-and-retreat method for trailer loading and which trainers advocate for it?

Approach and retreat is the foundational method most modern natural horsemanship trainers use for trailer loading, and it is arguably the most universally effective technique available because it works with the horse's flight instinct rather than against it. The principle is simple but requires patience to execute correctly: you ask the horse to move toward the trailer, allow it to get as close as it can without panicking, then retreat slightly before the horse decides to flee on its own. You approach again, stay a little longer, go a little closer, then retreat again. Pat Parelli, Clinton Anderson, Warwick Schiller, and John Lyons all use variations of approach and retreat, though they arrive at it through different philosophical frameworks. Parelli frames it as building confidence and teaching the horse that the human will always give it a release. Anderson frames it as making the right thing easy and the wrong thing difficult while ensuring the horse gets to think through the problem. Schiller frames it as regulating the horse's nervous system by never pushing it past the point where it can process information. The critical detail that separates effective approach and retreat from ineffective application is timing. The retreat must happen before the horse decides to leave on its own. If you wait until the horse is already pulling back or spinning, you have missed the window — you are now chasing the horse away from the trailer rather than teaching it to be comfortable. The release should come the moment you see the horse think about going forward, not after it has already committed to going backward. Done correctly, approach and retreat breaks trailer loading into hundreds of small successful tries rather than one overwhelming confrontation.