Motor Skills

Gentile’s Two-Dimensional Taxonomy for Classifying Motor Skills

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

When makig decisions about appropriate skill activities, motor skill instructors must frequently take into account the performance demands placed upon individuals. Although one-dimensional classification systemsOpens in new window effectively discriminate among different classes of motor skills based on several important task considerations, they are less effective in delineating among skills based upon performance demands.

What is often required is a system for grouping motor skills into categories based upon similar performance characteristics (recall here the analogous situation with the two definitions of motor skillOpens in new window discussed at the beginning of this series, with the classic definition assuming a task perspective and Guthrie’s definition taking a performance perspective in defining motor skills).

In response to this need, Gentile (1972, 2000) broadened the categorization of motor skills into a two-dimensional system comprising a taxonomy having 16 skill categories.

Gentile’s original purpose in creating her taxonomy was to provide a tool for physical therapists to more effectively evaluate the motor skill proficiencies of their patients and to determine appropriate treatment protocols.

Although Gentile’s taxonomy was originally designed for use in physical and occupational therapy, its use has broadened to encompass instructional design considerations in many movement-related fields and today is used in sports, physical education, performing arts, and industrial settings.

The taxonomy underpins evaluation and instructional decisions across a wide spectrum of applications and provides an important tool for movement practitioners in all fields involving the acquisition and performance of motor skills.

Gentile’s taxonomy starts by classifying all skills on the basis of two dimensions influencing performance. These include the demands placed upon individuals by the environment as well as those requirements imposed by the task itself.

Environmental Demands

The first dimension in Gentile’s taxonomy considers the demands placed upon individuals by the environment in which a skill is performed, and is labeled Environmental Demands in the taxonomy (see Table X-1). Two characteristics of the environment are considered in the taxonomy. Gentile referred to these as regulatory conditions and intertribal variability.

Regulatory conditions refer to those features of the environment that are relevant to how a skill must be performed. Regulatory conditions specify and constrain the actions a person must execute.

Features of the performance environment including spatial dimensions, obstacles and the arrangement of objects within the performance space, the nature of the supporting surface on which a skill is performed, wind and lighting conditions, and the presence of other people are examples.

An important distinction in Gentile’s taxonomy is whether regulatory conditions are stationary or in motion. As this description indicates, stationary regulatory conditions are stable and do not demonstrate relevant change within the environmental context. The initiation and timing of action is, given stationary regulatory conditions, under the control of the performer.

In-motion regulatory conditions, also as the term implies, refer to those conditions in which relevant features of the environment change or are in motion during the performance of a skill, imposing how the initiation and timing of action must be controlled. The distinction between stationary and in-motion regulatory conditions in Gentile’s taxonomy is, in this case, the same as the one-dimensional system distinction between closed and open skills.

Gentile’s taxonomy extends the distinction between closed and open skills further, however, by considering also the notion of intertribal variability. A second feature of environmental context demands classified by Gentile is whether regulatory conditions remain the same or change from one performance attempt to the next, referred to as intertribal variability.

Although many skills performed in stationary regulatory conditions show few if any environmental changes from one attempt to another (e.g., a basketball free throw), others are marked by both environmental stability and trial-to-trial environmental change (e.g., billiards).

Likewise, in-motion regulatory conditions can also exhibit intertribal variability (e.g., driving on a busy street), probably the most typical situation, or little or no variability (e.g., stepping on to a moving escalator). In Gentile’s taxonomy, intertribal variability is classified as being either absent or present.

Action Requirements

The second dimension classified by Gentile’s taxonomy pertains to the actions required in performing a skill. Specifically, Gentile classified two aspects of a performer’s bodily actions. These include what she termerd body transport and object manipulation (see Table X-1).

Body transport refers to whether a person must change location when performing a skill. Playing soccer and snow skiing both demand changes in a performer’s spatial location. Some skills may involve bodily transport as the primary goal of performance (e.g., a 100-yard dash), whereas for others the requirement to change location imposes additional demands on other performance goals (e.g., moving to avoid a defender before taking a shot in basketball).

Other skills require no change in location in order to accomplish the skill successfully (e.g., performing a sit-up, driving a golf ball). In addition to considerations of body transport, a second essential feature of action requirements is whether the manipulation of an object, or of other individuals, is required when performing a skill.

Many motor skills require the performer to manipulate objects (e.g., swing a golf club, throw a ball) or other people (e.g., wrestling, square dancing) when performing the skill. Although such manipulations are frequently accomplished using the hands, other body segments may also be involved (e.g., kicking a soccer ball, blocking in football). As with internal variability, object manipulation is classified as being either absent or present.

Gentile’s 16 Skill Categories

To classify skills within Gentile’s taxonomy, the four environmental demand conditions (stationary and in-motion regulatory conditions, the absence or presence of intertribal variability) are crossed with the four possible action requirements (body stability or transport, the absence or presence of object manipulation) to yield 16 skill categories. Table X-1 illustrates the taxonomy along with examples of two skills in each of the 16 categories.

Each of the 16 categories into which skills can be classified imposes a different set of demands on performers. Gentile specified that as the number and complexity of environmental and task demands to which a performer must attend and control increases, the difficulty of task performance also increases (Gentile, 2000).

In the taxonomy, environmental demands increase with movement down the categorical columns, whereas action requirements increase with movement from left to right across the categorical rows.

Skills in the upper left-hand category represent the simplest and least difficult skills to perform, whereas those skills in the bottom right-hand category are the most complex and demanding.

For ease of reference, categories are labeled by number from 1 to 4 down columns, and by letter from A to D across rows, with an increase in either direction indicating greater skill complexity.

As skills move diagonally across the columns from left to right, and down the rows from top to bottom, performance demands increase, with skills in category 1A being the simplest, and those in category 4D the most complex.

Application of Gentile’s Taxonomy

Because the categorical classification of skills in Gentile’s taxonomy progressively increases in task difficulty with movement across columns and down rows, the taxonomy can be used to assess and compare different skills, or variations of the same skill, in regard to demands placed upon performers. This makes possible two important applications of the taxonomy.

First, as Gentile originally intended when developing the taxonomy, it can be used to evaluate an individual’s level of movement proficiency.

As a diagnostic tool in physical therapy settings, the taxonomy provides an effective method for gauging a patient’s movement capabilities and limitations (Huxham, Goldie, and Patla, 2001). For example, a therapist could evaluate a patient recovering from hip replacement surgery by first assessing the patient’s ability to stand on a flat surface and maintain balance while extending his or her arms in various directions (category 1A in the taxonomy).

If the patient demonstrated sufficient confidence and capability performing these actions, the same activity could be tested with the patient holding and moving a beanbag from hand to hand (category 1B).

Progressively, the patient could be asked to walk a short distance with hands free (category 1C), and then while carrying a beanbag in both hands (category 1D). If the patient were able to perform all of these actions successfully, the therapist could then repeat the same sequence but vary the intertribal regulatory conditions by having the patient attempt each skill progression on a flat unencumbered surface, a carpeted surface, and a flat surface where movement around a chair or other obstacle was required (progression in this sequence would be from 2A to 2D).

By gradually varying task demands, the therapist can accurately evaluate a patient’s level of movement proficiency, prescribe appropriate training activities for the patient’s current level of movement capabilities, and meaningfully measure progress over the course of treatment.

In the example just cited, an important feature of the evaluation sequence can be observed. That is, beyond simply evaluating an individual’s current movement capabilities, the taxonomy effectively charts a progression of increasingly challenging activities. This leads to a second major use of the taxonomy, which is the identification of systematically more demanding skill variations.

In our example, if the patient was capable of standing on a flat surface while manipulating beanbag but was not able to maintain stability when attempting to walk, the taxonomy could be used by the therapist to effectively plan a progressive sequence of treatment activities.

Because the patient starts at category 1B in the taxonomy, the most immediate goal of treatment would be to emphasize walking on a flat surface while remaining unencumbered by any demands for manipulating objects (category 1C).

Progressively, as the patient could successfully meet the challenges of each new category, the therapist would devise activities representing the next category in order to continually, in gradual steps, increase the patient’s movement capabilities.

The use of Gentile’s taxonomy to plan meaningful instructional progressions in a variety of skills and performance settings has provided an effective tool for movement practitioners when planning instructional activities. When used in physical education settings, the taxonomy provides a coherent framework for curricular development (Adams, 1999).

The teacher instructing a unit of softball, for example, may observe that a particular class of students is having difficulty learinging to bat when thrown pitched balls. In this case, the instructor may decide students are not ready for the demands imposed by live pitches (i.e., both regulatory and intertribal variability) and could reduce these challenges to manageable levels by stabilizing environmental conditions.

To do this, the teacher could have students learn correct movement patterns by hitting the softball from a batting tee set at an appropriate midbody level while maintaining both feet in place (category 1B).

Progressions could then be planned to practice hitting movements without a bat but by moving the front foot toward the tee and “stepping into the pitch” (category 1C); by adding the bat and htting the ball while stepping forward (category 1D); and then by repeating the same activities while varying the height of the tee on which the ball is placed (categories 2A to 2D).

Once skill proficiency in these categories was attained, the progressions would be repeated with a pitcher throwing the same type of pitch on each trial (categories 3A to 3D) and finally with the pitcher throwing a variety of different pitches (categories 4A to 4D).

The systematic and incremental increase in task demands made possible by using Gentile’s taxonomy provides the instructor with a useful tool for meaningfully planning an effective series of progressively challenging, yet manageable, steps in meeting skill goals. It can also be noted that instructors may decide to begin progressions within any categorical steps may be omitted depending on learner needs andn progress.