Visual and Proprioceptive Integration in Reaching Movements.
Poster Presentation

Hendrikus J. (Dirk) Snijders
Department of Experimental Psychology, University of Oxford / Department of Biomedical Sciences, University of Utrecht

Nicholas P. Holmes
Department of Experimental Psychology, University of Oxford

Charles Spence
Department of Experimental Psychology, University of Oxford

     Abstract ID Number: 138
     Full text: PDF
     Last modified: June 29, 2005

Abstract
According to an optimum integration model visual and proprioceptive information concerning hand position will be integrated depending on their accuracy in a given direction. A mirror was used to displace the apparent location of a hand and create a conflict between vision and proprioception (“mirror illusion”). When participants made forward or sideways reaching movements to a two-dimensional array of targets, the visual and proprioceptive information was expected to be weighted and integrated differentially and result in differing reaching errors varying with direction.

It was found that reaching errors were generally greater in a left-right direction. This suggests a greater weighting of visual information in this direction than in the, more proprioceptively accurate, depth direction. The error was greater in a forwards reach than in a sideways movement.

During motor planning a phase of movement vector formulation would require extensive visual input whereas the execution into motor commands would rely more on proprioceptive input. An additional experiment in which eye-movements were precluded showed no effect of multisensory conflict on reaching movements. Eye-movements appear to play a large role in establishing a movement vector and performing a reaching movement under a “mirror illusion”.