higher levels of (reward) uncertainty, slower sustained activations of the dopaminergic system have been shown to increase (Fiorillo et al., 2003; Preuschoff et al., 2006). The current results related to late CNV amplitude are in line with this finding. The amplitude is lowest for cues that do not predict reward. Not only do these trials not feature reward, but reward uncertainty is also lowest here (for both high-difficult and low-difficult trials). In reward trials, reward uncertainty is present in both conditions, but most pronounced when cues predict a high-difficulty trial; correspondingly the largest CNV amplitude has been detected in this condition. However, considering the established characteristics of the CNV as a typical preparatory component reflecting anticipatory attention and motor preparation, this uncertainty-based interpretation appears less likely as the full explanation of the data pattern than the task-preparation-related account.
