Error-related Negativity (ERN) is a signal that is associated with error detection. Joch and colleagues (Journal of Neurophysiology 118:486-495, 2017) successfully separated the ERN as a response to online prediction error from feedback updates. We discuss the role of ERN in action, and suggest insights from VR techniques; we consider the potential benefit of self-evaluation in determining the mechanisms of ERN amplitude; finally we review the oscillatory activity that has been claimed to accompany ERN.