Breaking the reflectional symmetry of interlimb coordination dynamics.

Area of Science:

• Human motor control
• Biomechanical dynamics
• Coordination science

Background:

• Interlimb rhythmic coordination typically exhibits reflectional symmetry when limb parameters are identical.
• Breaking symmetry in frequency or spatial orientation challenges this inherent coordination pattern.

Purpose of the Study:

• To investigate how temporal and spatial asymmetries influence stable states in interlimb coordination.
• To determine if broken symmetry maintains or alters reflectional relationships in movement patterns.

Main Methods:

• Four experiments involving 31 participants were conducted.
• Participants performed rhythmic coordination tasks with limb segments acting as ordinary or inverted pendulums.
• Symmetry was systematically broken by altering timing (frequency) and spatial orientation.

Main Results:

• When symmetry was broken only by timing differences, stable states remained reflectionally related, consistent across pendulum types.
• When both temporal and spatial symmetry were broken, distinct stable states emerged but were still reflectionally related.
• These states differed from those produced by identically oriented pendulums.

Conclusions:

• Symmetry breaking in interlimb coordination leads to one of several symmetrically related stable states.
• Coordination dynamics can be extended to accommodate both temporal and spatial asymmetries within a framework of reflectional symmetry.