HK: Motor Learning and Performance (Chapter 1)

Variable Error

A measure of the subject's inconsistency - how different each individual score was in comparison to his average (CE) score. To compute variable error (VE), we square the difference between each trial's error score and the subject's own constant error [(X₁ - CE)²], sum those over all of the trials, and divide by N. Now, since these are squared values, we return them to their original state by computing the square root of this value. VE = √ [ ∑ ( X₁ - CE)² / N]

Empirical Phenomenon

Empirical Phenomenon is explained by how the theorist describes the ways in which the hypothetical constructs interact with each other

Continuous Skill

Has no particular beginning or end, the behavior flowing on for many minutes, such as swimming and knitting.

Statements

Hypotheses take the form of statements such as "If I ask learners to practice under condition x, then learning should be enhanced."

Performing skills

Implies some desired environmental goal such as holding a handstand in gymnastics or being able to walk again after a stroke.

Skill

The ability to bring about some end result with maximum certainty and minimum outlay of energy, or of time and energy.

A theory

A human-made structure whose purpose is to explain how various phenomena occur.

Investigations from the early 1900s

1. Investigations of relatively complex, high-level skills such as telegraphy and typing 2. Studies by biologists and physiologists concerning the fundamental mechanisms of neural control of muscle, muscle force production, and the study of nerves and the nervous system

Constant Error

The most obvious way to determine which subject was more accurate is to compute the error deviation of each throw, relative to the target, and then calculate the average of these error deviations. After the error scores for each trial are computed the mean can then be calculated to determine the average error deviation. This is the subject's average constant error. CE = [∑ (X₁ - T) / N] ∑ = the "sum of" i = trial number X₁ = score for the i-th trial T = the target distance N = number of trials

Skills involve achieving well-defined environmental play by:

1. Maximizing the certainty of goal achievement 2. Minimizing the physical- and mental- energy costs of performance 3. Minimizing the time used

Three Elements Critical to Almost Any Skill

1. Perceiving the relevant environmental features 2. Deciding what to do and where and when to do it to achieve the goal 3. Producing organized muscular activity to generate movements that achieve the goal

Concept of Science (implies...)

1. The active use of theory and hypothesis testing to further our knowledge 2. A certain "infrastructure" that involves books and journals, scientific organizations that deal with both the fundamental aspects of the science and ways to apply the knowledge to real-world situations, and granting agencies to provide funds for research 3. The existence of courses of study of the area in universities and colleges

Minimazation

A third feature of skills is minimization and thus conservation of the energy required for performance. For some skills there is clearly not the goal, as in the shot put, where the only goal is to throw the maximum distance. But for many other skills the minimization of energy expenditure is critical, allowing the marathon runner to hold an efficient pace or allowing the wrestler to save strength for the last few minutes of the match. We evolved to walk as we do, because our walking style minimizes energy expenditure for walking a given distance.

AE vs CE vs VE

AE was used as a measure of error very frequently until Schutz and Roy (1973) pointed out some statistical difficulties with it. Today, investigators tend to use CE (as a measure of average bias, or directional error) and VE (as a measure of inconsistency). Sometimes investigators use a statistic called absolute constant error ( abbreviated | CE | ) instead of CE for a subject's measure of bias. The |CE| is simply the average absolute value of the computed CE score as defined previously. The advantage is that |CE| retains the magnitude of average deviation from the target but prevents two scores from "canceling out" when subjects are averaged together to present a group score.

Absolute Error

Another relatively obvious way to combine the scores into a single number is to consider the absolute value (i.e. with the sign ignored or removed) of the error on each trial, and take the average of those error scores for the various trials. AE = [ ∑ (| X₁ - T | / N ] The vertical bars mean "absolute value of."

Minimum Energy Notion

Applies not only to the physiological energy costs but also to the psychological or mental energy required for performance. Many skills have been learned so well that the performers hardly have to pay attention to them, freeing their cognitive processes for other features of the activity, such as strategy in basketball or expressiveness in dance. A major contributor to the efficiency of skilled performance is, of course, practice, with learning and experience leading to the relatively effortless performances so admired in highly skilled people.

Serial Skill

Between the polar ends of the discrete-continuous-skill continuum is the serial skill - it is often thought of as a group of discrete skills strung together to make up a new, more complicated skill action. The word "serial" implies the order of the elements is usually critical for successful performance.

Skills and Minimum Time

Many skills have this as the only goal, such as a swimming race. Minimizing time can interact with the other skill features mentioned. Surgeons who conduct invasive surgery need to work quickly to minimize the opportunity for infections to enter the body. Yet surgeons obviously need to work carefully, too. Speeding up performance often results in imprecise movements that have less certainty in terms of achieving their environmental goals. Also, increased speed generates movements for which the energy costs are sometimes higher.

Skills vs Movements

Movements do not necessarily have any particular environmental goal, such as idly wiggling one's little finger. Skills consist of movements because the performer could not achieve an environmental goal without making at least one movement.

Closed Skill

One for which the environment is stable and predictable. Examples include swimming in an empty lane in a pool and drilling a hole in a block of wood.

Open Skill

One for which the environment is variable and unpredictable during the action. Examples include most team sports and driving a car in traffic where it is difficult to predict the future moves of other people.

Root-Mean-Square Error (RMSE)

RMSE is a common method used by researchers who study tracking tasks. One does this by computing the distance of the subject's tracking response from the target line at set distance-points along the track (e.g. every 10 ft of highway traveled) or, more commonly, at a constant interval of time along the track (i.e. every 100 ms). This method effectively "slices" the movement into equal intervals of tracking behavior, from start to finish. The RMSE is a more complex measure of performance than any of the error scores for discrete tasks because it represents two components of behavior. The RMSE reflects both the subject's bias tendency as well as inconsistency in the tracking behavior (how variable the performance tends to be). It is well recognized as a very good measure of how effectively the person tracked.

RMSE

Root-Mean-Square Error Tracking tasks are sometimes scored using a particular error score.

Logical Deduction

Scientists determine certain predictions that the theory makes in its current form, using logical deductions. These predictions form th basis of hypotheses that can be tested, typically in a laboratory.

Sensory factors

Sensory factors require the split-second analysis of patterns of sensory input, such as discerning that the combined movements of an entire football team indicate that the play will be a running play to the left side. These perpetual events lead to decisions about what to do, how to do it, and when to do it. These decisions are often a major determinant of success. Finally, skills depend on the quality of movement generated as a result of these decisions.

Serial vs Discrete Skills

Serial skills differ from discrete skills in that the movement durations tend to be somewhat longer, yet each component retains a discrete beginning and end. One view of learning serial skills suggests that the individual skill elements present in early learning are somehow combined to form one large, single element that the performer controls almost as if it were truly discrete in nature (e.g. the smooth, rapid way a gymnast shifts from one maneuver to another on the rings).

Hypothetical constructs

The theorist comes up with imaginary elements, or pieces, that interact in various ways in the theory.

Similarities between Open and Closed Skills

These "open" and "closed" designations actually mark only the end points of a continuum, with the skills lying in between having varying degrees of environmental predictability or variability.

Closed Skill vs Open Skill

This classification points out a crtical feature for skills, defining the performer's need to respond to moment-to-moment variations in the environment. It brings in the subprocesses associated with perception, pattern recognition, and decision making (usually with the need to perform these processes quickly) so the action can be tailored to the environment. These processes are minimized in closed skills, where the performer can evaluate the environmental demands in advance without time pressure, organize the movement in advance, and carry it out without needing to make rapid modifications as the movement unfolds.

Skills and Performance Goals

To be skilled implies meeting this performance goal, this "end result," with maximum certainty. For example, while playing darts a player makes a bull's-eye. But this by itself does not ensure that he is a skilled darts player because this result was achieved without very much certainty. Such an outcome could have been the result of one lucky throw in the midst of hundreds of others that were not so lucky. To be considered "skilled" requires that a person produce the skill reliably, on demand, without luck playing a very large role. This is one reason why people value so greatly the champion athlete who, with but one chance and only seconds remaining at the end of a game, makes the goal that allows the team to win.

Tracking

Tracking is a continuous skill in which the performer's limb movements control a lever, a wheel, a handle, or some other device to follow the movements of some target-track. Tracking movements are very common in real-world skills situations and much research has been directed to their performance and learning. Tracking tasks are sometimes scored using a particular error score, called root-mean-square error (RMSE).

Discrete Skill

Usually has an easily defined beginning and end, often with a very brief duration of movement, such as throwing a ball, firing a rifle, or turning on a light switch. Discrete skills are particularly important in both sport and daily actions, especially considering the large number of discrete hitting, kicking, and throwing skills that make up many sport activities, as well as everyday skills of fastening buttons, writing your signature, and tying your shoelaces.