What does Warwick Schiller say about horses that are behind the bit and how does it develop?

A horse behind the bit — one whose nose is tucked behind the vertical, breaking at the third vertebra rather than at the poll — is something Warwick Schiller addresses as almost always a human-created problem rather than a natural horse tendency. His explanation of how it develops is both clear and uncomfortable for many trainers to hear. Schiller's diagnosis is that horses get behind the bit when the bit has been used in a way that gave the horse no correct answer for the pressure. A horse that was ridden with constant contact and never given a genuine release learned that the pressure never goes away, so finding a position that reduces the pressure — tucking behind the vertical — became the strategy. A horse that was pulled on strongly learned that ducking behind the bit reduced the severity of the pull. In both cases the horse found that behind the vertical was more comfortable than in front of it. His solution is not to ride the horse forward into the bit with leg pressure — which can temporarily produce a horse in front of the vertical while the leg is active but does not address why the horse prefers behind the vertical. His solution is to change the bit's association through patient work with a completely following, non-resistive contact and precise release timing. The horse needs to learn that light bit contact is followed by immediate release when it comes to the contact — which requires the rider to release at exactly the right moment, which requires both feel and patience. Clinton Anderson addresses behind-the-bit horses by checking first whether the bit is causing pain — a horse that gets behind to escape a painful bit needs the pain addressed, not a different training approach. Once pain is ruled out, his correction involves returning to two-handed snaffle work with deliberately lighter contact than has previously been used, rebuilding the horse's willingness to work in front of the bit by ensuring every try toward the correct head position is met with immediate release.