Visual-Tactile Integration: Does Stimulus Duration Influence the Relative Amount of Response Enhancement?
Poster Presentation

Stefan Rach
Department of Psychology, Oldenburg University, Germany

Adele Diederich
School of Humanities and Social Sciences, International University Bremen, Germany

     Abstract ID Number: 29
     Full text: Not available
     Last modified: March 6, 2006
     Presentation date: 06/19/2006 10:00 AM in Hamilton Building, Foyer
     (View Schedule)

Abstract
Neurophysiological studies on higher mammals suggest that the benefits of multisensory integration are larger for less intense stimuli, that is, inverse effectiveness: the relative amount of multisensory response enhancement (MRE) is inversely related to stimulus intensity (Stein & Meredith, 1993, MIT Press). This finding is supported by behavioral studies on humans that showed an inverse relation between the magnitude of intersensory facilitation and stimulus intensity.

Two experiments were conducted to investigate whether inverse effectiveness might apply also to stimulus duration. Participants were required to perform saccades to visual targets positioned left or right from fixation, while, on some trials, ignoring tactile non-targets that were presented either spatially aligned or contralateral to the visual target (focused attention paradigm). Stimulus duration of both target and non-target varied. Saccadic reaction times were recorded.

Both experiments revealed that the largest relative amount of intersensory facilitation (in terms of MRE) was elicited by the shortest stimuli and that MRE decreased with increasing stimulus duration, thus, inverse effectiveness of stimulus duration.