Movement vigor as a traitlike attribute of individuality

Area of Science:

• Neuroscience
• Motor Control
• Human Individuality

Background:

• Individual differences in evaluating effort and reward influence decision-making and motor control.
• Classic motor control theories propose vigor differences reflect a speed-accuracy trade-off.

Purpose of the Study:

• To test whether movement vigor is an individual trait reflecting effort expenditure or a speed-accuracy trade-off.
• To investigate the conservation of movement vigor across different motor modalities (eyes, head, arm).

Main Methods:

• Measured eye, head, and arm movements in healthy humans during elementary tasks.
• Characterized individual movement vigor (peak velocity) relative to population norms.
• Assessed reaction time and end-point accuracy for each movement type.

Main Results:

• Individuals exhibited consistent differences in movement vigor (low vs. high).
• High vigor individuals showed shorter reaction times and linked vigor across arm and head movements.
• Movement vigor did not affect end-point accuracy, refuting the speed-accuracy trade-off hypothesis.
• Vigor was conserved across skeletal movements (arm, head) but not eye movements.

Conclusions:

• Movement vigor appears to be an individual trait reflecting a propensity to expend effort, not a willingness to sacrifice accuracy.
• The conservation of vigor across skeletal movements suggests a common neural mechanism for effort evaluation in these modalities.
• Divergence of eye movement vigor indicates distinct neural control or evaluation processes for oculomotor control.