Event-related potentials (ERPs) are changes in the electroencephalogram (EEG) caused by sensory and cognitive processes. In schizophrenia, ERP deficits are associated with cortical synaptic pathophysiology, such as NMDAr (N-methyl-D-aspartate receptor) hypofunction, which is related to cognitive impairment experienced by these patients. For example, mismatch negativity (MMN) is an ERP associated with auditory novelty detection. MMN is impaired and correlates with cognitive and global function in patients with schizophrenia. The ability to measure a biomarker like MMN may play a predictive role in schizophrenia drug development.