Electroencephalographic Changes during Brief Periods of Perceptual Deprivation

16 schizophrenic Ss, exposed to a bright structureless visual field in a perceptual deprivation situation, showed mean decreases of 0.25 cycles/second ( p < .05) in alpha frequencies measured from occipital EEGs. The mean decreases in alpha frequency occurred during both sessions in a drug-placebo test and retest, without the amount of the mean change significantly differing between drug vs placebo, or first vs second testing. The decreases correlated with a measure of perceptual field-dependency but not with ratings of symptomatology or of the amount and quality of visual imagery reported by Ss. Such frequency decreases, comparable to those measured by other investigators over 7-day periods of perceptual deprivation, are suggested to depend upon conditions of high input levels of unpatterned optic stimulation.