A common external reference frame for tactile localization
Poster Presentation

Tobias Schicke
Dept. of Psychology, University of Hamburg

Brigitte Röder
Dept. of Psychology, University of Hamburg

     Abstract ID Number: 18
     Full text: Not available
     Last modified: February 1, 2006
     Presentation date: 06/19/2006 10:00 AM in Hamilton Building, Foyer
     (View Schedule)

Abstract
Performance in temporal order judgements (TOJ) of two tactile stimuli, one presented to each hand, is worse when the hands are crossed as compared to a parallel hand posture, indicating a remapping of tactile stimulus location from an anatomical into a non-anatomically, possibly external spatial reference frame. Such use of external coordinates has been suggested to facilitate efficient visual-manual control. The present studies tested if the use of a non-anatomical reference frame for tactile localization is restricted to those regions of space that are accessible by sight, and if it is a specific feature of hand use.
In experiment 1, participants made TOJs while they held their hands in front of or behind their trunk. TOJs were equally impaired by hand crossing in both regions of space, demonstrating that the use of non-anatomical coordinates are not restricted to visible space.
In experiment 2, participants made TOJs about stimuli delivered to the hands, the feet, or one hand and one foot. The stimulated limbs were either uncrossed or crossed. TOJs similarly declined due to limb crossing in all conditions, even when two different types of limb were stimulated.
The two studies suggest that all body parts are remapped into common external coordinates and that this remapping is therefore not a specific feature for eye-hand-coordination. Common coordinates may be of advantage for action control, which often involves an updating of the location of all body parts with respect to an external action goal.