Trajectory Adaptation to a Non-linear Visuomotor Transformation: Evidence
of Motion Planning in Visually Perceived Space.
FLANAGAN, J. RANDALL AND ASHWINI K. RAO.
Department of Psychology, Queen's University, Kingston, Ontario, Canada K7L
3N6 and Department of Movement Sciences, Teachers College, Columbia
University, New York, NY 10027.
APStracts 2:0206N, 1995.
Summary and Conclusions
1. Although reaching movements are characterized by hand paths which tend to
follow roughly straight lines in Cartesian space, a fundamental issue is
whether this reflects constraints associated with perception or movement
production. 2. To address this issue, we examined two-joint planar reaching
movements in which we manipulated the mapping between actual and visually
perceived motion. In particular, we used a non-linear transformation such that
straight line hand paths in Cartesian space would result in curved paths in
perceived space and vice versa. 3. Under these conditions, subjects learned to
make straight line paths in perceived space even though the paths of the hand
in Cartesian space were markedly curved. In contrast, when the motion was
perceived in Cartesian space (i.e., in the absence of a non-linear
distortion), straight line hand paths were observed. 4. These findings suggest
that visually guided reaching movements are planned in a perceptual frame of
reference. Reaching movements in the horizontal plane are adapted so as to
produce straight lines in visually perceived space.
Received 19 May 1995; accepted in final form 17 July 1995.
APS Manuscript Number J334-5.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.