Influence of auditory stop-signals on visually guided saccadic eye movements

J. Oezyurt, H. Colonius

SFB Neurokognition, Universität Oldenburg, Germany (e-mail:oezyurt@psychologie.uni-oldenburg.de)

In a stop-signal task subjects are instructed to perform a reaction time (RT) task, but must withhold their response as soon as a stop-signal is presented. Stop-signals occur unpredictably at different time points after presentation of the go-signal. In this study, the effect of auditory stop-signals on saccades towards a visual target is investigated. The spatial distance between the visual target and the auditory stop-signal was varied, whereby the position of the stop-signal was controlled via a virtual acoustic environment. The data are tested against the horse-race model (Logan & Cowan, 1984) which holds that RT's and stopping performance are exclusively determined through the relative finishing times of the go- and stop-processes, assumed to be stochastically independent random variables. We found the RT data are in agreement with the model. However, changes in movement parameters such as hypometric saccadic amplitudes and reduced peak velocities in signal-respond trials indicate a violation of the independence assumption of the model. The spatial position of the auditory stop-signal did not show an effect on performance.