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The Ebbinghaus illusion affects on-line movement control.
Ingrid Handlovsky1, Steve Hansen, Timothy D Lee
1Department of Kinesiology, McMaster University, Hamilton, Ont., Canada L8S 4K1.
Neuroscience Letters
|August 4, 2004
Summary
Movement speed for discrete aiming tasks changed based on visual illusions. Faster movements occurred when targets appeared larger, indicating online control adjustments, challenging existing models.
Area of Science:
- Cognitive Psychology
- Motor Control
- Visual Perception
Background:
- The Ebbinghaus size-contrast illusion influences perceived target size.
- Understanding how visual illusions affect motor planning and execution is crucial.
Purpose of the Study:
- To investigate how the Ebbinghaus illusion impacts the planning and online control of discrete aiming movements.
- To test the validity of current models of motor control against observed behavioral changes.
Main Methods:
- Participants performed discrete aiming movements towards visual targets.
- The Ebbinghaus size-contrast illusion was introduced and removed during movement execution.
- Movement time and its components were analyzed to infer control mechanisms.
Main Results:
- Aiming movements were executed faster when targets appeared larger due to the illusion after movement initiation.
- The observed changes in movement time were primarily linked to the online control phase of the movement.
- Movement planning appeared less affected by the illusion compared to online adjustments.
Conclusions:
- The findings challenge established models like the planning and control model and the perception and action dissociation model.
- Motor control systems demonstrate adaptability, adjusting movements online based on perceived visual feedback.
- This suggests a more dynamic interaction between perception and action than previously assumed by some models.