Repetition Without Repetition: Challenges in Understanding Behavioral Flexibility in Motor Skill

Abstract

A hallmark of skilled motor performance is behavioral flexibility-i.e., experts can not only produce a movement pattern to reliably and efficiently achieve a given task outcome, but also possess the ability to change that movement pattern to fit a new context. In this perspective article, we briefly highlight the factors that are critical to understanding behavioral flexibility, and its connection to movement variability, stability, and learning. We then address how practice strategies should be developed from a motor learning standpoint to enhance behavioral flexibility. Finally, we highlight some important future avenues of work that are needed to advance our understanding of behavioral flexibility. We use examples from sport as a context to highlight these issues, especially in regard to elite performance and development.

Performance Variability During Motor Learning of a New Balance Task in a Non-immersive Virtual Environment in Children With Hemiplegic Cerebral Palsy and Typically Developing Peers

“…Our variability metric did not enable us to partition variability into adaptive or error components. Using more sophisticated statistical models to understand the structure of variability can provide more insight into randomness and exploration patterns ( 31 , 32 ). Example methods that could be useful for exploring the structure of different solutions in simple redundant tasks include the Tolerance, Noise and Covariation Approach (TNC), the Uncontrolled Manifold Approach, and the Goal-Equivalent Manifold approach; readers are directed to Sternad ( 32 ) for an overview.…”

“…Variability is usually reduced with practice of a new motor skill. A prevalent view is that variability impedes the accuracy and precision required for skill attainment (31,32). In contrast, some amount of variability may be beneficial to support the search for optimal solutions in differing task conditions (33)(34)(35).…”

“…Variability, traditionally conceptualized as the opposite of stability, is a fundamental characteristic of human performance ( 31 , 32 ). Sternad defines variability as an umbrella term for “all sets or series of observations that are non-constant” ( 32 ).…”

“…Indeed, Hadders-Algra defines variability as “the capacity to select from the repertoire the motor strategy that fits the situation best” ( 36 ). Ranganathan et al ( 31 ) relate this view of variability to behavioral flexibility, which they define as “the ability to achieve the same task outcome using different movement solutions.” Whether adaptive or detrimental, variability can occur at the level of task performance (in performance outcomes) and at the level of movement execution (in kinematic strategies used to achieve the outcome). Exploring both within-child (e.g., variability across different timepoints) and between-child variability (e.g., variability between children at the same timepoint) at both task and movement levels is important to understand differences in children's responses to interventions ( 37 ).…”

“…Less is known about task performance variability in non-immersive VEs. Exploring this issue is important to contribute to the ongoing discussion about variability as both an adaptive and detrimental characteristic of motor learning ( 31 , 32 ). Greater knowledge about within- and between-child variability in performance can provide new information relevant to conclusions about intervention effectiveness and inform sample size considerations for clinical trials.…”