Integrated measures of electroencephalogram (EEG) amplitude and its variability over time, and of mean alpha frequency, have been applied to study the responses of six schizophrenic and six nonpsychotic volunteers to 45-minute periods of perceptual deprivation (PD), as compared to a prior condition of resting, eyes-closed but perceptually structured state. Interpreting results in relation to the concept that the integrated EEG measures reflect cortical activation states, field dependency and diagnostic grouping are found to interact to a statistically significant degree in their effect on the integrated EEG measures. Alpha frequency changes do not relate to diagnosis but only to field dependency status, suggesting that field-dependent subjects become more generally aroused under PD as compared to pre-PD, while field-independent subjects tend to become less aroused. The alpha frequency changes do not correlate with changes in the integrated EEG measures. The various EEG changes are discussed in relation to possible systems of general arousal and of selective cortical inhibition, and to clinical observations of schizophrenics' “paradoxical” response to perceptual or sensory isolation.