Motor biases reflect a misalignment between visual and proprioceptive reference frames

Area of Science:

• Neuroscience
• Motor Control
• Computational Neuroscience

Background:

• Goal-directed movements rely on accurate perception and motor systems.
• Errors in these systems can lead to movement failures, including systematic motor biases.
• The precise origin of these systematic biases is a subject of ongoing debate.

Purpose of the Study:

• To evaluate computational models explaining the origin of motor biases.
• To investigate whether motor biases arise from sensory or biomechanical factors.
• To identify the primary cause of systematic motor biases in human movements.

Main Methods:

• Analysis of extensive reaching task data spanning 30 years.
• Evaluation of various computational models of motor bias.
• Comparison of model predictions against empirical data from human participants.

Main Results:

• Motor biases do not originate from errors in sensed hand position during motor planning.
• Biomechanical constraints during motor execution do not explain motor biases.
• Motor biases are primarily caused by a misalignment between eye-centric and body-centric position representations.

Conclusions:

• The proposed model of spatial representation misalignment accounts for motor biases across diverse conditions.
• This includes variations in hand used, movement type, starting position visibility, and sensorimotor adaptation.
• The findings challenge previous theories and offer a unified explanation for motor biases.