“Headset” is a bad word in my vocabulary.

Thankfully, most horse show judges these days aren’t swayed by that horse with his nose tucked in – they’re looking past the head to analyze the balance, rhythm and relaxation of the whole picture.

I often describe the horse as in a box, a shape or frame. The rider sends him forward from her legs (the back of the box) into the bit, into her hands (the front of the box). The horse rounds his top line, softens to the bit and the energy springs upward rather than running forward. But when the front and the back of the box are rigid, or their boundaries inconsistent, the horse learns to

lean on them (the heavy horse)
fight them (rooting the reins out of the rider’s hands)
or avoid them (behind the bit).

Once a horse learns how to escape the noisy or inconsistent hands of a rider, he’ll tend to hide behind the bit even with a rider of educated hands, avoiding the annoyance before it begins. In equitation science, this is called “avoidance conditioning”. He’s found an escape route that works and behind the bit becomes his default, whether or not the threat is still present.