Second-order motor planning difficulties in children with developmental coordination disorder

Area of Science:

• Neuroscience
• Developmental Psychology
• Motor Control

Background:

• Second-order motor planning, crucial for anticipating movement consequences, is often impaired in children with developmental coordination disorder (DCD).
• Previous studies using end-state comfort (ESC) paradigms have limitations, as children might prioritize comfort over task demands, masking true planning deficits.

Purpose of the Study:

• To investigate second-order motor planning abilities in children with and without DCD using a novel task that minimizes the influence of comfort preferences.
• To determine if DCD is associated with difficulties in adjusting initial motor plans based on anticipated task requirements.

Main Methods:

• Fifty-two children (aged 5-12 years), with and without DCD, performed a hexagonal knob rotation task with varying angles (60°, 120°, 180°, 240°).
• The task design, particularly larger rotation angles, necessitated uncomfortable starting postures, preventing prioritization of comfort over planning.
• Performance was assessed by grip adjustments, task success rates, and temporal movement parameters.

Main Results:

• Children with DCD demonstrated significantly fewer anticipatory grip adjustments and higher task failure rates compared to typically developing (TD) children.
• While reaction time increased with rotation angle in both groups, this effect was less pronounced in children with DCD.
• No group differences were observed in the timing of movements after the initial planning phase.

Conclusions:

• The findings confirm genuine second-order motor planning deficits in children with DCD.
• Difficulties appear to stem from the initial movement planning stage, preceding the execution of the motor act.
• The novel task effectively isolated second-order planning deficits, overcoming limitations of previous ESC paradigms.