Abstract <p>Processing negativity (PN) is the potential in the differencewaves between directed attention and the absence of attention tostimuli, reflecting the effectiveness of selective attention, however,it has been little studied, especially in mental disorders. 62 men wereexamined: 22 with schizophrenia spectrum disorders, 22 with personalitydisorders and 18 mentally healthy volunteers. Auditory evoked potentialswere recorded in the oddball paradigm in two conditions: active(pressing a button on a deviant stimulus) and ignore (watching avideo). Difference waves of PN (“active”–“ignore” condition), MMN(“deviant”–“standard” stimuli) and P300 (averaged evoked potentialto a deviant stimulus) were calculated. A pointwise <i>t</i>-test, rmANOVA, topographic mapping, andcorrelation analysis were conducted. Three subcomponents were identifiedin the PN difference wave: early negative (PN, 60–160 ms), positive(PP, 250–400 ms), and late negative (LN, 400–600 ms). Significantdifferences in PN amplitude were found between groups, with thehighest amplitude observed in subjects with personality disorders.Altered PN topography was observed in subjects with schizophreniaspectrum disorders. The PP and P300 amplitudes in the active conditionshowed high correlations and overlapping topographies. No significantbetween-group differences were found for MMN and P300 parameters.PN proved to be a more sensitive marker of attentional deficitsthan well-studied components. Increased PN in personality disordersmay reflect attentional hyperreactivity, while topographic changesin schizophrenia may reflect dysfunction of frontoparietal networks.PP is a similar context updating process to P3 that is activatedeven by standard stimuli in a directed attention condition. PN subcomponentshave diagnostic potential for assessing impairments in selective attentionin schizophrenia and personality disorders.</p>