NORMAL STARTLE RESPONDING IN PSYCHOSIS-PRONE COLLEGE-STUDENTS

Some researchers have predicted that subjects with high scores on ques tionnaires of psychosis-proneness would show deficiencies in the habit uation and prepulse inhibition of the startle reflex, similar to those seen with schizophrenics. In two experiments, startle eyeblink EMG wa s measured in physical anhedonics, perceptual aberrators, and normal c ontrols. In Experiment 1 (N = 64), eyeblink amplitude and probability habituated to both 85 and 100 dB SPL acoustic pulses. In Experiment 2 (N = 48), acoustic prepulses at intensities of 55 or 70 dB SPL were pr esented with stimulus onset asynchronies (SOAs) of 60 or 120 msec befo re startle-eliciting stimuli at intensities of 85 and 100 dB SPL. Inhi bition of startle was generally more pronounced when the prestimulus w as more intense and at a longer SOA, and when the eliciting stimulus w as more intense (for response amplitude). In both experiments, startle responses were larger and more probable for more intense eliciting st imuli. Also, the diagnosis group variable had no significant effect in either experiment. These results demonstrate that college students wh o produce high scores on scales of psychosis-proneness may not provide a good model for the perceptual gating deficits which have been demon strated in schizophrenic patients, with regard to automatic measures o f stimulus processing.