What is one of the effects when activating the curb rein on a Pelham bit?

When activating the curb rein on a Pelham bit, one of the primary effects is that it can lower the horse's head. The Pelham bit is designed to provide both direct pressure from the snaffle action and leverage from the curb action. When the curb rein is engaged, the leverage causes the horse's head to drop, encouraging the horse to relax its neck and respond to the rider's cues more willingly. This head lowering effect is beneficial for establishing a more balanced outline and improving the quality of movement, as it encourages the horse to engage its hindquarters and travel with a more rounded frame.

While raising the horse's head is typically associated with more upward pressure on the bit or improper use, using the curb rein correctly aims to create a soft downward response. Options suggesting that it allows the rider full use of one rein or provides no direct response do not accurately reflect the intended effects of the Pelham bit's design and usage.