Comparing the auditory and visual stop task: A psychophysiological study.

Overtoom, C. C. E.1,2, Vlierman, R. C. 1 , Kenemans, J. L.1, and van der Molen, M. W.2
1Department of Psychopharmacology, Faculty of Pharmacy, Utrecht University, The Netherlands; 2Department of Developmental Psychology, University of Amsterdam, The Netherlands

Background: Successful stopping in the stoptask with an auditory stopsignal is associated with more fronto-central positivity (P3) compared to unsuccessful stopping (De Jong et al., 1990; Overtoom et al., 2002). On the other hand stopping with a visual stopstimulus evoked more negativity (Pliszka et al., 2000). It seems that successful stopping in the auditory modality is associated with more positivity and that in the visual modality stopping is associated with more negativity. Falkenstein et al. (1999) reported the presence of a visual N2 at NoGo trials in a Go/NoGo task but this negativity was absent in the auditory modality. It could be that the presence of positivity or negativity is modality specific. Therefore we investigated in the current study both modalities in the stoptask and expected an N2 in the visual stoptask and fronto-central positivity in the auditory task.

Methods: Performance and event-related potentials (ERPs) from 18 adults were compared in a visual and auditory stop-task. ERPs were recorded from 64 electrodes.

Results: The stop-signal reaction time (SSRT) was shorter in the auditory condition than in the visual one. The fronto-central positivity(P3) was present in both modalities and was larger in the successful stoptrials compared to the unsuccessful stoptrials. Furthermore, the longer SSRT in the visual condition could also be identified in a latency shift of the visual P3. However, no N2 was detected in either task.

Conclusions: The absence of the N2 in both stoptasks may indicate that the N2 might be more interpreted in terms of a response conflict than to be related to inhibition.