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The visual guidance of catching
G J Savelsbergh1, H T Whiting, J R Pijpers
1Faculty of Human Movement Sciences, Free University, Amsterdam, The Netherlands.
Experimental Brain Research
|January 1, 1993
Summary
Catching relies on visual expansion cues, not just ball size. Optimal catching requires specific visual information available 200-300ms before contact.
Area of Science:
- Visual perception
- Motor control
- Human factors
Background:
- The optic array provides crucial information for visually guided actions like catching.
- Understanding the specific visual cues used in catching is essential for explaining perception-action coupling.
Purpose of the Study:
- To investigate the role of optical expansion patterns and viewing time in one-handed catching.
- To determine the critical time window for visual information in successful catching actions.
Main Methods:
- Subjects caught balls with varying optical expansion and viewing durations in a dark room.
- Liquid crystal spectacles occluded vision at 0, 100, 200, or 300 ms before impact.
- Catching actions were analyzed using retinal expansion, grasp velocity, and ball size adjustments.
Main Results:
- Catching timing is primarily based on retinal expansion information.
- Occluding the last 300 ms of ball trajectory delayed hand closing velocity but not opening velocity.
- Catching adjustments differed significantly between 0 ms and 300 ms occlusion conditions.
Conclusions:
- Relative optical expansion information between 200-300 ms before contact is vital for continuous perception-action coupling during catching.
- Catching actions are dynamically adjusted based on available visual information, emphasizing the importance of early visual cues.