The antipointing task: vector inversion is supported by a perceptual estimate of visual space

Area of Science:

• Motor Control
• Human Movement Science
• Neuroscience

Background:

• Reaching movements exhibit endpoint biases, particularly mirror-symmetrical movements (antipointing).
• The underlying mechanisms of these biases, whether visuomotor inhibition or vector inversion, remain debated.

Purpose of the Study:

• To investigate the cause of visual field-specific endpoint bias in antipointing movements.
• To differentiate between visuomotor inhibition and vector inversion as explanations for antipointing biases.

Main Methods:

• Participants performed pro- and antipointing movements in left and right visual space.
• Experiments utilized blocked and random trial conditions to manipulate movement type presentation.
• Premovement inhibition was assessed across conditions.

Main Results:

• Propointing movements showed consistent accuracy across visual fields.
• Antipointing movements exhibited endpoint biases (undershooting/overshooting) in both blocked and random conditions.
• The random condition demonstrated equivalent premovement inhibition for both movement types.

Conclusions:

• The visual field-specific bias in antipointing is not solely due to visuomotor inhibition.
• Vector inversion, supported by integrated visuoperceptual networks, is proposed as the primary mechanism.
• The obligatory nature of antipointing tasks contributes to this bias.