One of the brain functions presenting more interest within the study of cognitive neurosciences is attention, which has a voluntary and an involuntary component. Involuntary attention is related to the detection of potentially relevant stimulus but originally not attended. It is considered that involuntary attention is made up by at least three stages: a) an automatic mismatch detection of a stimulus related to a given sensory context, b) an involuntary attention change associated to the orientation response, and c) a re-orientation towards the originally carried out task. The three-stage model of involuntary attention has been originated mainly based on the results obtained by Event Related Potentials (ERP) technique, by which three electrophysiological components associated with each stage of the theoretical model have been identified: mismatch negativity (MMN), P3a, and reorientation negativity (RON). This work reviews describing experimental, morphological, and topographic characteristics of each one, as well as their appearance through the development, and their alteration in clinical populations, such as traumatic brain injury, alcoholism and attention deficit disorder, is made. Finally, research perspectives are defined for future studies.
