abstractHumans have the ability to interact with the environment by producing voluntary movements and responding to relevant external events. Since human performance is rarely perfect, an important task of the human information processing system also concerns the monitoring of actions (Rabbitt, 1967). In this way departures from required performance are detected and adjustments can be made to eliminate, or reduce, errors. This thesis describes experiments on the planning, execution and evaluation of voluntary movement. To this end, brain activity in the electro-encephalogram (EEG) accompanying both hand and eye movements are examined.text