According to the break hypothesis, which statement best describes how movement is controlled?

• A. To sit still, you release brakes on all movements except reflexes that maintain an upright posture.
• B. To sit still, you must put the brakes on all movements except those reflexes that maintain an upright posture.
• C. To move, you release all brakes and rely on reflexes for control.
• D. To move, you must keep brakes on all postural reflexes and release brakes on voluntary movement.

Answer: (B)

Movement is thought to be controlled by a braking system that normally keeps the body still. To prevent unwanted action, most movements are held in check by these brakes, while automatic postural reflexes—those that help keep you upright—operate without needing to release those brakes. When you want to move, you release the brakes in a controlled way, allowing voluntary action while still relying on reflexes to maintain stability.

That’s why the statement describing sitting still as putting brakes on all movements except those reflexes that maintain an upright posture fits best. It captures the idea that stillness is achieved by braking most motor activity, with postural reflexes left to maintain balance.