How preparation to touch or grasp alters visual size perception.

Area of Science:

• Cognitive Psychology
• Visual Perception
• Motor Control

Background:

• Visually guided actions may be less susceptible to certain size illusions.
• Previous research indicated reduced illusion magnitudes in action components.

Purpose of the Study:

• To investigate if reduced illusion magnitudes in action components extend to conscious perceptual judgments.
• To characterize how visual size perception is altered by size-mediated behaviors.

Main Methods:

• Participants judged target sizes verbally or by reaching to grasp/touch.
• Visual illusions were induced using contextual elements (e.g., Ebbinghaus illusion).
• Illusion magnitudes were compared across verbal and action-oriented tasks.

Main Results:

• Illusion magnitudes were significantly smaller when participants performed or imagined actions.
• This reduction in illusion magnitude persisted after returning to verbal judgments.
• A motor interference task abolished the illusion reduction effect.

Conclusions:

• Engaging in or imagining actions alters visual size perception, reducing illusion susceptibility.
• Visual processing shifts associated with action persist beyond the motor task.
• Motor interference suggests a link between motor preparation and illusion magnitude reduction.