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Motor Skills Characteristics

Motor skill development File photo | Credit: Aussie Child Care NetworkOpens in new window

Having defined motor skills in the previous articleOpens in new window, here we inquire into the characteristics common to motor skills. What features do all motor skills share in common? This is far from a question for mere speculation.

In approaching the scientific study of motor skills, our assumptions, theories, and findings must remain embedded within the shared framework of such characteristics. Indeed, any theory or research finding must ultimately be tested by its ability to adequately address, and shed light upon, such shared characteristics.

In identifying the characteristics common to all motor skills, Sheridan (1984) has proposed that any adequate theory of motor skills must address at least four essential characteristics common to all motor skills. These include motor equivalence, motor variability, motor consistency, and motor modifiability.

Motor Equivalence

Motor equivalence refers to the capacity to produce many different movement patterns to accomplish the same action goal.

Humans are highly flexible in the ways they can move to meet environmental demands. Flexibility of action is achieved by recruiting different muscles and joints to achieve the same skill goal (by organizing different movements to accomplish the same skill goals).

For example, you can catch a ball with either your dominant or nondominant hand, turn on a light switch using your elbow when your hands are filled with packages (you can even use your nose), or sign your name holding a pen between your teeth while writing on a piece of paper.

These are examples of skilled action accomplished with effectors we would not normally use to complete a given motor skill, but which nonetheless can often be done with great effectiveness even when we may never have attempted the action in exactly the same way before.

This capacity to accomplish the same environmental skill goal in many different, and often quite varied ways, is referred to as “motor equivalence”, and denotes the many equivalent ways we can move and still accomplish the action goal.

Although we typically accomplish such equivalent movements with considerable ease, the explanation of how we do so remains a complex and debated queston among motor behavior theorists (Kelso et al. 1998).

Motor Variability

Motor variability refers to the notion that, no two movement patterns, even of the same skill, are ever produced in exactly the same way.

The uniqueness of human action—the fact that no two skills are ever accomplished in exactly the same way—is a second characteristic of human motor skills.

Even when we watch a highly skilled performer completing successive repetitions of the same stereotypical skill—such as a tennis player hitting balls projected by a ball machine—the repeated actions are never completed in exactly the same way.

Slight variations are evident, for example, in how the body is positioned prior to contacting the ball, in the kinematic patterns of limb movements during skill execution, and in the kinetic forces generated to accomplish the skill.

More striking yet, the same neural pathways are never used successively in completing the same skill, nor are the same motor units recruited and patterned the same way to control muscular forces.

Even when movement skills may appear nearly identical to an observer, at the neurological level they are markedly different, with movements organized and assembled through vastly different architectures of neural routes, synaptic impulses, and collectives of muscle fibers.

This suggests that the movement patterns underlying motor skills are not rigidly constructed, but that new solutions to movement problems must be found each and every time a skill is performed, even if that skill has been performed in more or less the same way thousands of times previously. This phenomenon is called motor variability, and is one of the most challenging problems in the study of motor skills.

Motor Consistency

Motor consistency refers to the capacity to achive the goals of motor skills consistently; the capacity of the human motor system to learn.

Even though all motor skills are unique, as we have just seen, still we learn to move in skillful ways. That is, even though we never produce a skill in exactly the same way twice, in those skills for which we practice and become good, we are highly consistent from one time to the next in achieving the same outcome.

A highly skilled baseball pitcher never uses the same neural pathways in throwing a fastball (even after throwing perhaps hundreds of thousands of fastballs), yet his fastball is consistent in striking out batters. This ability to accomplish the same movement goal, which is improved through experience and practice, is termed motor consistency.

How we learn to produce such skilled actions, given the variability of each movement, is a problem motor learning specialists must answer if their theories of motor control and learning are to have the greatest explanatory power.

Motor Modifiability

Motor modifiability is the capacity to alter a movement pattern to achieve a new action goal.

The final characteristic for which any theory of motor skills must account is that of a skilled performer’s ability to modify an action once its execution has begun. Observing any athletic performance involving the need for athletes to quickly react to rapidly changing game situations will provide many examples of this characteristic.

Examples could include, for instance, a baseball player who begins to swing at a pitched ball but then quickly lets up, stopping his swing when it becomes obvious the ball is not in the strike zone, or a basketball player starting to take a shot and then quickly changing her actions to pass the ball to a teammate when a defender covers her too closely.

The ability to change an action quickly once it has begun is termed motor modifiability.

Again, as with the other characteristics listed here, it is easily accomplished—often seemingly effortlessly—but a complex phenomenon when we begin to attempt a scientific explanation of it.

In summary, the characteristics listed above and common to all motor skills present challenging problems in the study of motor skills, even when in practice their solution may seem achieved with considerable ease. This leads us to a consideration of the problems confronting us in the study of motor skillsOpens in new window.

See also:
  1. Adams, DL. (1999). “Develop better motor skill progressions with Gentile’s Taxonomy of Tasks,” Journal of Physical Education, Recreation, and Dance, 70(8), 35 – 38.
  2. Gentile, AM. (2000). “Skill acquisition: Action, movement, and neuromotor process.” In J Carr and R Shepherd (eds.), Movement Science: Foundations for Physical Therapy and Rehabilitation (pp. 111 – 188). Gaitherburg, MD: Aspen Publications.
  3. Sheridan, MR. (1984). “Planning and controlling simple movement.” In MM Smyth and AL. Wing (eds.), The Psychology of Movement (pp. 47 – 82). London: Academic Press.
  4. Wulf, G, and Shea, C. (2002). “Principles derived from the study of simple skills do not generalize to complex skills.” Psychonomic Bulletin & Review, 9, 185 – 211.
  5. Haywood, KM, and Getchell, N. (2004). Life span motor development, 4th ed. Champaign, 1L: Human Kinetics.
  6. Lashley, KS. (1951). “The problem of serial order in behavior.” In LA Jeffress (ed.), Cerebral mechanisms in behavior: The Hixon symposium (pp. 112 – 136). New York: Wiley.
  7. Smyth, MM, and Haggard, P. (1999). “Movement and action: Introduction to the special topic,” British Journal of Psychology, 90(12), 243 – 246.
  8. Kelso, AS, Fuchs, A, Lancaster, R, Holroyd, T, Cheyne, D, and Weinberg, H. (1998). “Dynamical cortical activity in the human brain reveals motor equivalence.” Nature, 392, 814 – 818.
  9. Kramer, AF, Strayer, DL, and Buckley, J. (1990). “Development and transfer of automatic processes,” Journal of Experimental Psychology: Human Perception and Performance, 16, 505 – 522.
  10. Jeannerod, M. (1994). “The representing brain: Neural correlates of motor intention and imagery.” Brain Behavior and Science, 17, 187 – 245.
  11. Guthrie, ER. (1952). The psychology of learning. New York: Harper & Row.
  12. Gentile, AM. (2002). “Skill acquisition: Action, movement, and the neuromotor processes.” In JH Carr and RB Shepherd (eds.), Movement science: Foundations for physical therapy in rehabilitation, 2nd ed. (pp. 111 – 188). Rockville, MD: Aspen Press.
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