The visuomotor system resists the horizontal-vertical illusion.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Visual Perception

Background:

• The horizontal-vertical illusion demonstrates how visual perception can be distorted.
• Understanding the dissociation between perception and action is crucial for cognitive neuroscience.

Purpose of the Study:

• To investigate the impact of the horizontal-vertical illusion on both visual perception and visuomotor control.
• To determine if the visuomotor system is susceptible to the same perceptual distortions as the visual system.

Main Methods:

• Participants (N=8) viewed inverted-T stimuli with horizontal and vertical lines.
• Judged line segment lengths to assess perceptual susceptibility to the illusion.
• Reached and grasped line segments to evaluate visuomotor system performance.

Main Results:

• Perceptually, participants were influenced by the horizontal-vertical illusion, misjudging line lengths.
• Visuomotor control, specifically grip aperture scaling, was accurate and unaffected by the illusion.
• A dissociation was observed between the perceptual and visuomotor systems' responses to the illusion.

Conclusions:

• The findings support a dual-stream model of visual processing, proposing separate pathways for perception and action.
• Visuomotor control appears to be more robust against certain visual illusions than conscious perception.
• This research provides evidence for distinct neural mechanisms underlying visual perception and visually guided actions.