perpétuo e sem limites geográficos, de arquivar e publicar esta dissertação através de exemplares impressos reproduzidos em papel ou de forma digital, ou por qualquer outro meio conhecido ou que venha a ser inventado, e de a divulgar através de repositórios científicos e de admitir a sua cópia e distribuição com objectivos educacionais ou de investigação, não comerciais, desde que seja dado crédito ao autor e editor. To my Friends and Family ACKNOWLEDGEMENTSFirst and foremost, I want to show my gratitude to my Dissertation adviser for giving me the opportunity to carry out a project in an area for which a have a keen interest: BrainComputer Interfaces. I would like to thank everyone at IBEB that has helped me and gladly volunteered to take part of the studies I conducted. I would also like to acknowledge the staff and faculty of my University, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa for providing me with the academic tools and expertise to carry out my thesis, and hopefully to build a strong professional career.Secondly, I want to thank all my friends for providing moral support and inspiration.My university pals, A Centopeia and my recent friends that have accompanied me throughout a bumpy year. Also, a special thanks to my Erasmus buddies, the Wolfpack, who give me the drive to work hard so we can reunite as often as possible. Lastly, I want to thank my good friends from the North, whom I have met the longest, and always provide an escape to the troublesome life in the Capital.