Gridlines and Symmetry

Type: Macro-movement principle Perceptual skill targeted: Spatial

In any macro-movement, imagine gridlines in your peripersonal space and trace those gridlines with various body landmarks — hipbones, bottom of the ribcage, base of the neck, etc.

Key gridlines:

• The Midline — the nose, chin, sternum, pubis line; organizes “the Rectangle” of shoulders and hips around it
• T-arms line — arms at shoulder height form a straight line through wrist–shoulder–shoulder–wrist
• Hip-width parallel lines — ankles, knees, and hips move strictly within sagittal planes projecting from these lines (e.g., in a squat hinge)
• Torso–thigh/leg line — in a lunge, torso aligns with the back leg
• Straight ankle — whenever the foot is off the floor or on tiptoe, the ankle remains neutral (no inversion/eversion)

Function: Creates clear spatial reference frames, reducing ambiguity in movement goals. GS is hypothesized to refine frontoparietal action maps and enhance affordance perception.

GS → DA interaction: In naturally asymmetric movements, forcing symmetry through GS produces more widespread muscular co-contraction — making GS a secondary trigger for Distributed Activation.

Related

• The Six Principles
• Fixing-Separating-Isolating — companion macro-movement principle
• Spatial Awareness
• Distributed Activation — GS can generate DA as a secondary effect