Ashley Griffin, University of Kentucky
All current equine learning research is based on the assumption that horses learn through Stimulus - Response - Reinforcement - Training (S - R - R - T).
The horse perceives a stimulus, or cue, such as the rider's leg or body weight (seat).
The horse then makes a random response to the stimulus.
If the response is correct, the horse receives positive reinforcement (reward).
If the incorrect response is given, the trainer either ignores the response and/or repeats the stimulus or applies negative reinforcement until the horse makes the correct response.
Now, let's examine the different parts of S - R - R - T.
Research has shown that horses learn as well with a single stimulus as as they do with a combination of visual, auditory, and tactile stimuli.
Horses are very adept at discriminating between the slightest stimulus in their environment and one that occurs as part of asking them to perform. Therefore, trainers must be specific and consistent with their presentation of stimuli, otherwise known as cues. If the specific cue and timing of each cue is not similar, the horse will begin to generalize in response to stimuli and won't respond appropriately. If inconsistency persists, then a stronger, more obvious stimulus will be required to generate the proper response and achieve the initial or new level of responsiveness.
A good example would be the riding lesson horse. Riding lesson horses become so habituated to accidental stimuli from beginning riders that they become dull and unresponsive (hard-sided) to subtle stimuli. Theses horses learn to ignore the cues of the riders and instead walk, trot, and canter based on voice commands of the riding instructor.
It is important that stimuli be given consistently and at the proper time for the horse to respond with the proper maneuver. If the horse's body is not in the right position, there is no way it can give the proper response. For example, the only time a horse can move its front left leg laterally is when that leg is in the air. Therefore, the best time to present the stimulus for moving the leg laterally is when it is moving forward and off the ground.
The correct timing of a stimulus is where the art of good horsemanship joins the science of learning.