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An Objective and Child-friendly Assessment of Arm Function by Using a 3-D Sensor
Published on: February 12, 2018
Toy-oriented changes in early arm movements III: constraints on joint kinematics
1Infant Motor Behavior Laboratory, Department of Physical Therapy, and the Biomechanics and Movement Science Program, University of Delaware, Newark, DE 19716, USA.
Infant Behavior & Development
|August 9, 2007
Summary
Early arm movements show consistent shoulder and elbow coordination, suggesting inherent constraints. Task-specific constraints emerge later, simplifying the learning process for reaching.
Area of Science:
- Developmental neuroscience
- Motor control
- Biomechanics
Background:
- Understanding the developmental trajectory of infant reaching is crucial for identifying factors that influence motor learning.
- Prereaching movements offer insights into the foundational constraints that shape more complex goal-directed actions.
Purpose of the Study:
- To identify invariant kinematic features in shoulder and elbow movements during prereaching in infants.
- To explore how the presence of a toy influences these movement features.
- To understand the relationship between early arm movements and the development of reaching.
Main Methods:
- Kinematic analysis of shoulder and elbow joint movements during prereaching tasks.
- Comparison of movement patterns with and without a toy present.
- Longitudinal observation of kinematic changes in the weeks preceding the onset of reaching.
Main Results:
- Shoulder joint excursion and movement smoothness were consistently greater than the elbow, indicating significant organismal constraints.
- Increased speed differences between shoulder and elbow occurred only when a toy was present, suggesting task-specific constraints.
- These task-related constraints appeared in the 4 weeks leading up to the onset of reaching.
Conclusions:
- Organismal constraints on joint coordination during prereaching provide a basis for later task-related constraints.
- The coordinative structures of early arm movements and reaching may be more similar than previously assumed.
- This underlying similarity simplifies motor learning by reducing the number of elements requiring active control.
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