A horse responds to neck rein techniques when it has learned that a light pressure of the right rein against the horse's neck on that side means for the horse to turn left, and a light pressure of the other rein against the horse's neck on the left side means for the horse to turn right. When riders neck rein, they hold both reins in the left hand (if they are right-handed), and hold their lariat or other needed tool in their right hand. Moving the left hand to the left tells the horse to turn left, and moving the left hand to the right means for the horse to turn right. When first teaching a horse to neck rein, a trainer will cross the reins under the horse's neck so that the rein from the left side of the bit goes under the horse's neck and emerges on the right side of the horse's body and then goes on to the rider's hand. The other rein starts with the right bit ring and goes under the neck to emerge on the left. Then when the rider moves his hand to the left the horse feels pressure on the left side of the bit (which the horse should already know means to turn left) and simultaneously feels pressure from the rein on the opposite side of its neck. When the rider moves his hand to the right, the horse feels pressure on the right side of the bit and on the left side of the neck. Before long the horse anticipates bit pressure as soon as it feels pressure on the neck, and soon the reins can be uncrossed and the horse will still respond correctly to neck rein signals.
In English riding and other systems where the primary means of communication is light pressure between the rider's hands and the horse's mouth, light pressure is always maintained on the bit. In neck reining, the reins are left slack unless the rider needs to tell the horse to stop.
