Monitoring force errors: medial-frontal negativity in a unimanual force-production task

The effects of force production on medial-frontal negativity (MFN), reflecting the activity of an internal action-monitoring system, were investigated in a force-production task. A precue indicated a low or high force before a stimulus signaled the execution of the same or opposite force. An incorrectly exerted force was assumed to involve an error of force selection if the opposite force was required (invalid precue), and an error of force execution if the same force was required (valid precue). The task was repeated to examine any improvements in monitoring sensitivity. No force-related effects were observed on MFN amplitude. Although performance improved, there was no evidence of a force-error sensitive monitoring system. As the MFN and motor activity were affected by the precue invalidity regardless of the response outcome, the MFN might reflect the activity of a general action-evaluation system that is indirectly related to motor activation.