re-active distinction (e.g., Braver, 2012). Specifically, high task-difficulty in a reward context clearly engage pro-active control mechanisms, as indexed here be the CNV. In contrast, different levels of task difficulty in the no-reward condition of the current experiments might have invoked different levels of reactive control (i.e., during target processing), which could be difficult to detect in the target-related ERPs. A final option would be that participants did not invoke any additional control processes, neither pro- nor re-actively, for high-difficulty trials as compared to low-difficulty trials in the no-reward condition. The current ERP data cannot adjudicate between these alternatives.
