BackgroundSchizophrenia (SCZ) and bipolar disorder (BD) are associated with information processing abnormalities, including visual perceptual and cognitive impairments, that impact daily functioning. Recent work in healthy samples suggests that peak alpha frequency (PAF) is an electrophysiological index of visual information processing speed that is also correlated with cognitive ability. There is evidence that PAF is slowed in SCZ, but it remains unclear whether PAF is reduced in BD, or if slower PAF is associated with impaired visual perception and cognition in these clinical disorders. MethodsThe current study recorded resting-state brain activity (both eyes open and closed) with electroencephalography (EEG) in 90 SCZ participants, 62 BD participants, and 69 healthy controls. Most participants also performed a visual perception task (backward masking) and cognitive testing (MATRICS Consensus Cognitive Battery). ResultsWe replicated previous findings of reduced PAF in SCZ compared with healthy controls. In contrast, PAF in BD did not significantly differ from healthy controls. Further, PAF was significantly correlated with performance on the perceptual and cognitive measures in SCZ, but not BD. PAF was also correlated with visual perception in the healthy control group, and showed a trend-level correlation with cognition. ConclusionsTogether, these results suggest that PAF deficits characterize SCZ, but not BD, and that individual differences in PAF relate to abnormalities in visual information processing and cognition in SCZ.