The definition of negative reinforcement is an uncomfortable or painful stimulus which the animal can avoid by changing its behavior. All horse training, no matter how gentle or how harsh it is, uses negative reinforcement. It is the one thing all horse training methods share in common, and that's because pressure and the release of pressure is the way we communicate with horses. When you take the slack out of a lead, or a rein to ask a horse to stop or to turn, you are using pressure. When you add leg, or shift your weight in the saddle to signal a change of gait, you are using pressure.
Pressure is our universal language.
To be safe around horses, they need to learn to move away from pressure. The question is not whether we make this part of our training, but HOW we teach it to the horse . In clicker training pressure becomes information the horse uses to get to his reinforcement faster. Pressure is not meant to intimidate or cause pain. I begin by asking the horse to back in a confined area such as a stall or small paddock.