Multisensory processing in the redundant target effect: a warning concerning modality switch costs
Poster

Matthias Gondan
Psychology, Philipps University, Marburg, Germany

Kathrin Lange
Psychology, Philipps University, Marburg, Germany

Brigitte Röder
Psychology, Philipps University, Marburg, Germany

     Abstract ID Number: 83
     Full text: Not available
     Last modified: March 26, 2003

Abstract
When participants respond to stimuli of two modalities, faster reactions times are observed for simultaneously presented stimuli bimodal stimuli than for unimodal events (redundant target effect, RTE). Race models assert that the two stimuli are processed independently, and that the channel which "wins the race" triggers the response. As the reaction time gain is usually larger than predicted by these models, coactivation models have been suggested which assume a multisensory integration of the two stimuli at a specific stage along the processing pathway. In random stimulus sequences, reaction times have been found to be larger when a stimulus of one modality is preceded by a stimulus of a different modality (modality switch effect, MSE). It is shown in a simulation that the MSE can lead to a race model violation, pretending coactivation although there is not any. A modified race model test is proposed, which takes the MSE into account. In two simple reaction time RTE experiments with central and peripheral targets, significant MSEs and RTEs were observed. When correcting for the MSE, the race model could still be rejected for central, but not for peripheral targets. These data suggest that the RTE has been systematically overestimated in previous studies.