Simple reaction time to stimuli from different sensory modalities presented simultaneously typically is shorter than reaction time to a single stimulus. In this study, auditory, visual, and tactile stimuli were presented in different combinations and at varying stimulus onset asynchronies. Two different types of models for the observed reaction time facilitation effects are developed and tested. Separate activation (race) type models assume that stimulus information in different sensory channels is processed in parallel and independently while coactivation type models allow interactions across different channels. Using Boole's inequality as a test for separate activation models it could be shown that these models cannot predict as much facilitation as observed. A superposition and a diffusion model of coactivation provided a promising quantitative approximation to the data.
Contents: Facilitation of reaction time - Separate activation -
Coactivation - Stochastic models for reaction time - Superposition model -
Diffusion model.
The Author: Adele Diederich studied psychology, education, and mathematics at the Universities of Regensburg and Oldenburg. She held research assistant positions with Prof. Orth (Hamburg) from 1986 to 1988 and with Prof. Busemeyer (Purdue University, Indiana, USA) from 1989 to 1991. She currently has a postdoctoral fellowship at the Graduiertenkolleg Psychoakustik (psychoacoustics) at Oldenburg University.
