There has been considerable interest in event-related potentials as a biological marker of schizophrenia from the early 1970s (Roth & Cannon, 1972) when reduced amplitude and delayed latency of the P300 waveform were first reported. An auditory, visual, or somatosensory random and salient stimulus is presented to subjects who must make a response, such as pressing a button. Around 300 ms after the stimulus, an event-related potential can be detected across the scalp. This P300 waveform recorded from the scalp has several components that reflect selective attention and working memory in response to an unexpected change in the environment.
