Splitting

The practical skill of breaking a target behaviour into small enough pieces that the horse can succeed at each step. Splitting is the art that makes shaping work.

In successive approximation, the trainer reinforces behaviours that progressively resemble the final target. The size of the step between each approximation determines whether the horse can succeed. Steps too small produce inefficient training: the horse plateaus on a behaviour they have already mastered while the trainer waits for the criterion to be raised. Steps too big leave the horse unable to succeed, the reinforcement opportunity dries up, and training stalls or the behaviour deteriorates.

A skilled trainer reads the individual horse and adjusts the size of the next step accordingly. A confident, food-motivated horse who is offering behaviour generously can usually handle larger increments. A fearful or shut-down horse who is taking longer to offer behaviour needs much smaller increments, sometimes vanishingly small, to keep succeeding and stay engaged. The same target behaviour can be split into 10 steps for one horse and 50 steps for another, both legitimately.

The opposite of splitting is lumping: the trainer asks for too much of the final behaviour at once, the horse fails repeatedly, and the trainer either gets frustrated or gives up. Lumping is one of the most common reasons that shaping-based training fails in inexperienced hands. The fix is usually to go back several criteria and rebuild with smaller increments.

Splitting is not unique to clicker training or positive reinforcement. Pressure-release shaping uses the same principle: each release of pressure should reinforce a small step toward the final response, with the criterion for release raised gradually. Skilled trainers across methods rely on splitting to keep the horse succeeding and learning, regardless of which quadrant of operant conditioning is producing the reinforcement.