SENSORIMOTOR SKILL

also called perceptual-motor skill, or psychomotor skill any acquired ability to perform tasks in response to sensory stimuli. Certain motor acts occur automatically, such as blinking the eyes or retracting a finger from a hot surface. Many human motor skills, however, require practice. Such seemingly elementary skills as walking, eating, and dressing must be mastered through practice by every child. To acquire and perform such complex skills, a person must closely monitor sensory stimulation. One may need to use visual cues to judge the velocity and trajectory of an approaching object, or monitor the pressure applied by one's own muscles. Hence, the term sensorimotor skills reflects the idea that sensory and motor information must be integrated to accomplish such acts. Research suggests that motor abilities are actually an amalgam of basic components. Manual dexterity appears to be composed of subskills such as aiming ability, arm-wrist speed, and fine finger dexterity. Strength is separable into parts, including static strength, which is pounds of pressure exerted against an immovable object, and dynamic strength, the force exerted by limb movements. Acquiring a motor skill is thought to involve three distinct stages. In the first, called the cognitive stage, the person must comprehend the task requirements. Studies demonstrate that those individuals who were pretrained with a verbal or illustrative description of the task were more likely to master the skill. During the second, or intermediate stage, the individual must apply already acquired motor skills to the new task, master the motor skills unique to that task, and integrate the two to avoid inappropriate and unnecessary movements. In the final stage the skill becomes automatized, freeing the performer from thinking about each step of the process, and minimizing dependence on external cues. Fluid execution of motor skills on the part of accomplished performers has led researchers to think that sensorimotor skills are enacted via a motor program, a blueprint for the entire motor act, not just the sequencing of elements. This is well illustrated by the phenomenon of co-articulation. Speech production of the letter b in bat is different from the production of the b in beat. For such a distinction to occur, the brain must be aware that one b is followed by an a and that the other is followed by an ea, suggesting a preconceived plan for the whole utterance. As motor skills are attained, changes in attention to sensory cues and changes in reliance on feedback take place. While beginners rely mostly on external cues, someone who has mastered a skill will rely more on internal sources of feedback, such as those provided by muscles. The kind of formal instruction that aids most in perfecting motor skills varies for the early and later stages of acquisition. During the initial stages, the most essential factors for learning are perceptual awareness, an understanding of spatial relations, and comprehension of mechanical principles. Later, motor abilities such as speed of reaction, speed of movement, and coordination become critical. Retention of motor skills appears to be most dependent upon the degree to which the skill was perfected, rather than upon other variables such as the conditions under which it was learned. If a skill has been overlearned, exceeding a particular criterion, retention will be better than if such levels had not been reached initially.