Disruption of attention is a hallmark symptom of schizophrenia, and event-related potentials have been instrumental in studying this deficit in these patients. Prior studies have shown consistent reduction of the auditory P300 in schizophrenia, while visual attention findings have been mixed. Both the auditory and visual N2b, an earlier, modality-specific attention index, are often reduced in schizophrenia, sometimes despite sparing of the visual P300. Thus there may be a dissociation between N2b and P300 attention effects in the auditory and visual modalities in schizophrenia. This study used auditory and visual oddball tasks and two bimodal tasks, each with a modality-specific target. Results showed that the N2b was differentially impacted in the patient group across modalities, while the P300 remained intact. This evidence suggests non-reduction of the P300 may be due to effortful compensation for deficits in the more vulnerable N2b component of stimulus classification in patients with schizophrenia.