Arthi Murugesan/Chris Cramer Grad Student Presentation

 

Arthi Murugesan/Chris Cramer Grad Student Presentation

Sage 4101

March 5, 2008 12:00 PM - 1:30 PM

Chris Cramer:

Abstract: Theoretical and empirical evidence supporting two opposing control strategies has been reported in the literature on interceptive actions, such as one-handed catching.  The predictive approach assumes that visual information is used to make a prediction about the future position and motion of the object, which is then used to guide movement of the end-effector (i.e. the hand).  The prospective approach argues that visual information is used to guide the end-effector to the interception point without any prediction.  Re-examination of the evidence for both approaches, as well as investigation of comfort as an additional factor in these tasks forms the basis for this study.  Two experiments were conducted in a virtual environment.  Subjects wore a head-mounted display and caught virtual balls with their right hand.  First, we found little evidence that the control of hand position and orientation is influenced by misperceptions of trajectory that have been reported in other studies.  Such findings help to eliminate one argument against predictive control - that the future position and motion of the object cannot be predicted with sufficient accuracy to explain the success with which people catch balls.  Second, we found that the interception point is influenced by the end-state comfort of the hand.  This implies that people take their movement capabilities into account when deciding where to intercept the ball.  Third, we tested a prediction of the prospective control model that hand trajectories should reverse under some conditions.  Overall, this study provides support for a predictive control strategy.  

 

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