Modeling spatial effects in visual-tactile saccadic reaction time
Poster Presentation

Adele Diederich
School of Humanities and Social Sciences International University Bremen

Hans Colonius
Department of Psychology University of Oldenburg

     Abstract ID Number: 57
     Full text: Not available
     Last modified: March 17, 2005
     Presentation date: 06/05/2005 11:30 AM in MART Auditorium
     (View Schedule)

Abstract
Saccadic reaction time (SRT) to visual targets tends to be faster when non-visual stimuli are presented in close temporal or spatial proximity even when subjects are instructed to ignore the accessory input. The present study investigated visual-tactile interaction effects on SRT using a focused attention paradigm. Saccadic responses to bi- modal stimuli were reduced by up to 30 ms compared to responses to unimodal visual targets. In contrast to previous findings with visual- auditory stimulation, the amount of multisensory facilitation was not decreasing with the physical distance between target and non-target but depended on (i) whether both stimuli were presented ipsi- or contralateral, (ii) the eccentricity of the stimuli, and (iii) the frequency of the vibrotactile non-target. A recent time-window-of-integration (TWIN) model (Colonius & Diederich, 2004) allowing to separate effects of peripheral processing differences from multisensory interaction effects is presented and tested on the data. We evaluated 8 different versions of the TWIN model, differing with respect to their assumptions on the nature of the spatial effects, with respect to the data.