Effects of varying stop-signal probability on ERPs in the stop-signal task: do they reflect variations in inhibitory processing or simply novelty effects?
The aim of the present study was to determine whether ERP modulations associated with varying the probability of the stop-signal in the stop-signal task reflect variations in inhibitory processing, or whether they simply reflect general arousal associated with novel stimuli. This was achieved by examining the effects of probability on a control "ignore-signal" stimulus in addition to the stop-signal. ERP findings revealed large fronto-central N1 and P3 components that were larger in amplitude for stop-signals than ignore-signals, and when stimuli were rare (30%) compared to frequent (70%). However, probability effects were not greater for stop-signals compared to ignore-signals, discounting an interpretation exclusively in line with inhibitory processing. A principal components analysis (PCA) revealed a slow-wave ERP component that partially accounted for these probability effects. Together, the present findings indicate that ERP differences between rare and frequent stop-signals did not primarily reflect varying inhibitory requirements, but rather may be confounded by novelty effects.
Dimoska
Aneta
A
Department of Psychology and the Brain & Behaviour Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia. adimoska@med.usyd.edu.au
Johnstone
Stuart J
SJ
D000161:Acoustic Stimulation; D000328:Adult; D000465:Algorithms; D001143:Arousal / Q000502:physiology*; D003265:Contingent Negative Variation / Q000502:physiology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D025341:Principal Component Analysis; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D014796:Visual Perception