Final answer:
Ataxia is the movement disorder that affects a person's coordination, often resulting in difficulties with walking and maintaining posture.
Step-by-step explanation:
The term used to describe changes in a person's ability to perform coordinated motions, such as walking, is Ataxia. Ataxia is a movement disorder of the cerebellum, manifesting as a loss of coordination in voluntary movements. It may also refer to sensory deficits that lead to balance issues, often associated with deficiencies in proprioception and equilibrium. Damage to the cerebellum is a common cause of these symptoms. The manifestation of ataxia can be seen in gait and station problems, meaning difficulties with walking and maintaining a stable posture.