Selective inhibition is indexed by heart rate slowing

This study examined the hypothesis that global and selective inhibition are mediated by distinct mechanisms: respectively, a peripheral mechanism, ind exed by heart rate slowing, and a central mechanism, indexed by cortical bu t not autonomic measures. Three varieties of a Go-NoGo task were presented in which the Go signal required an index finger response rapidly followed b y a middle finger response. The NoGo signal required the inhibition of (a) both responses (global inhibition), (b) the middle finger response (simple selective inhibition), or (c) the index finger response of one hand and the middle finger response of the other hand (complex selective inhibition). A s anticipated, global inhibition was indexed by heart rate slowing. Most im portantly, heart rate slowing was also elicited by selective inhibition and was more pronounced for complex than simple selective inhibition. These fi ndings suggest that global and selective inhibition are mediated by one rat her than two mechanisms and that heart rate is sensitive to the demands pla ced on this inhibition mechanism.