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 execution.
• Errors in these systems can lead to systematic motor biases, influenced by target location.
• The precise origin of these systematic biases is a subject of ongoing debate.

Purpose of the Study:

• To investigate the underlying causes of systematic motor biases in goal-directed movements.
• To evaluate and compare various computational models explaining motor bias origins.
• To identify the primary source of systematic errors in motor planning and execution.

Main Methods:

• Analysis of extensive reaching task data spanning 30 years.
• Evaluation of multiple computational models for motor bias.
• Testing model predictions across diverse experimental conditions.

Main Results:

• Motor biases do not originate from errors in sensed hand position during motor planning.
• Biomechanical constraints during motor execution are not the primary cause of motor biases.
• A misalignment between eye-centric and body-centric position representations is the main driver of motor biases.

Conclusions:

• The proposed model, based on representational misalignment, robustly explains motor biases.
• This explanation holds across various contexts, including different effectors and sensory conditions.
• Findings challenge previous theories on the origin of systematic motor biases.