On the contrary, there is consistent evidence regarding alterations in sustained attention. Sustained attention is the ability to maintain attention and remain in a state of vigilance during a determined period of time. Some studies suggest that sustained attention is a valuable endophenotype for schizophrenia. However recently, Carter et al. argued that the attention deficits of patients with schizophrenia probably reflect a deficit in the modulation of the brain activity in response to transitory variations instead of a deficit in sustained attention. Failures in both these components of attention, selective and sustained attention, are based on the incapacity of eliminating irrelevant stimuli, which in turn is associated with inhibitory control. Different studies showed that inhibitory control is affected in schizophrenic patients14-17. This component has been related to the correct function of the executive attention system that participates in tasks involving conflicts within systems, where it is necessary to inhibit usual responses. These deficits in attention have been related to psychotic symptoms and this association is widely discussed. Some authors have found an inverse relation between the severity of negative symptomatology and the performance of schizophrenic patients in attention tasks, with no significant relation to positive symptomatology. On the contrary, other authors, like Krabbendam et al., have observed an inverse relation between positive symptoms, especially disorganization, and failures in inhibitory attentional control. Based on this contradictory background regarding the importance of the different components of attention in schizophrenic patients, the object of the present study was to assess and compare the role of attention span, selective attention, sustained attention and inhibitory attentional control processing in chronic schizophrenia. Our main hypothesis was that patients with chronic schizophrenia show general attention alterations, with the inhibitory component being the most affected. Additionally, any connections observed between the function of each attentional component and positive adnegative schizophrenic symptomatology were also studied.