Inability to fix the range of a movement.
Dysmetria is defined as an aspect of ataxia in which the ability to control the distance, power, and speed of an act is impaired (Stedman, 2000). The term originates from the Greek dys, meaning difficult or disordered, and metron, meaning measure. Individuals with dysmetria have problems judging the extent to which they must move their body to reach a desired goal and often have difficulty stopping their movement in a precise manner to reach the goal. Movements, therefore, undershoot (hypometria) or overshoot (hypermetria) the distance. Individuals with dysmetria may have difficulty raising their arms parallel to the floor (i.e., arms extended at the shoulder level). Some may also have problems moving their arms above their heads from their shoulders and back down while keeping their eyes closed.
An inability to control the range of movement (e.g., on trying to touch an object with an index finger).