Perceptual basis of bimanual coordination

Area of Science:

• Neuroscience
• Motor Control
• Human Action

Background:

• Periodic bimanual movements often exhibit a spontaneous tendency towards mirror symmetry.
• Involuntary slips into symmetry occur, but not vice versa, traditionally attributed to muscle co-activation.
• Previous interpretations linked this symmetry bias to motor neuronal structures.

Purpose of the Study:

• To investigate the underlying mechanisms of the symmetry bias in bimanual movements.
• To challenge the traditional view of motoric origins for this phenomenon.
• To explore the role of perceptual factors in organizing human actions.

Main Methods:

• Bimanual finger oscillation and four-finger tapping tasks were used as experimental models.
• Analysis focused on the nature of the symmetry bias, distinguishing between spatial and muscular origins.
• A bimanual circling model with visual feedback was employed to assess movement complexity and representation.

Main Results:

• The symmetry bias in bimanual movements is primarily towards spatial, perceptual symmetry, independent of specific muscles involved.
• Complex movements, even those seemingly 'impossible', can be executed with simple visual feedback.
• A dedicated 'motoric' representation of perceptual patterns is not necessary for movement execution.

Conclusions:

• Spontaneous coordination in bimanual actions appears to be perceptual rather than motoric.
• Voluntary movements are organized around representations of perceptual goals.
• Motor activity is flexibly tuned to achieve these perceptual goals, without complex internal model translations.