any scientific inquiry
6
. The lack of methods for the exclusion of hypotheses in studies of
motor learning has been highlighted elsewhere
7
. The present article aims to offer an
argument about how adopting a strong inference stance may advance our understanding
of the effects of extensive practice on motor learning.
This paper is organized as follows: we first review studies on extensive practice in
the scope of the Adaptive Process Approach. Then, we review studies on extensive
practice in the scope of the Specificity of Practice Hypothesis. Finally, in the last section,
we suggest a methodological way of contrasting the two perspectives in a single
experiment to gain more insights into the role of extensive practice in motor learning.
THE ADAPTIVE PROCESS APPROACH
The importance of the organization of structures of control for learning has been
highlighted by the proponents of the Adaptive Process Approach
2,3
. It is suggested that an
action program controls a motor skill. An important assumption in the Adaptive Process
Approach about how an action program controls a motor skill is that human beings are
open systems hierarchically organized
8
; consequently, an action program should also be
hierarchically organized in macro- and microstructures
9
.
The macrostructure is responsible for the components’ sequence and
organization, such as relative timing and relative force
10
. In this sense, the macrostructure
controls the important aspects for movement patterns or consistency in motor behavior,
which is a consequence of components’ organization based on the individual’s intention
9,10
. It is important because behavior consistency allows for reaching the goals with
reliability.
The microstructure is responsible for the movement variability, such as total time
and total force. Consequently, the microstructure controls the important aspects for
adaptability in motor behavior. Behavior adaptability is necessary since the environment
constantly changes, making it impossible to plan all the details in advance. Thus, the
microstructure is generated in every trial based on the constraints imposed by the
macrostructure
9,10
. Combining a selected macrostructure and a generated microstructure
in a single two-level control structure diminishes the central demand for controlling all the
motor skills aspects, addressing two of the main motor behavior features, i.e., consistency
and adaptability.
The agenda of the Adaptive Process Approach involves the investigation of how
the macro- and microstructures of action programs modify when facing different types of
perturbations. The general strategy of investigation involves assigning individuals to
different groups defined by their amounts of practice or levels of performance stabilization
of a given task. Stabilization refers to a state in which an individual has enough practice to
consistently reach the goal of a task, named as the performance criterion of the task
11,12
.
Of importance, although levels of stabilization are defined concerning results of movement
execution, levels of performance stabilization are suggested to reflect levels of
organization of systems’ internal constraints
12
.
Often, investigators are interested in comparing two levels of stabilization: practice
until the stabilization of performance (stabilization group) and practice beyond the