The debate behind the word "consciousness" has been vivid for centuries among ethicists, philosophers and neurologists. Distinguishing between different Disorders of Consciousness (DOCs) in after-coma patients, in particular, is still difficult, and the diagnosis is based on scales whose assignement may be subjective and thus mistaken. Finding an accurate mathematical way to interpret a patient's movements and understand if they are completely voluntary or just involuntary reflexes may be a more objective way to classify their level of consciousness. This thesis work proposes to find a way to distinguish among voluntary and involuntary movements in healthy subjects by analysing the Event Related Potentials (ERPs) behaviour obtained from EEG recordings.