Participants completed a rotated heads visual oddball task (Begleiter et al. 1984). Amplitude of the P300 wave was obtained at a midline parietal electrode (Pz) from the average ERP waveform derived from all target trials. P3 genetic factor score was generated from a factor analysis of P300 amplitude from multiple scalp electrode sites in four-member families (Malone et al. 2014b). P300 has been studied extensively in schizophrenia with visual and auditory tasks in case–control studies producing over 100 journal articles in the last 10 years (Bramon et al. 2004). Individuals with schizophrenia tend to have reduced P300 amplitude during the decision-making process as compared with controls (Jeon & Polich, 2003).
