Normal startle responding in psychosis-prone college students

Abstract

Some researchers have predicted that subjects with high scores on questionnaires of psychosis-proneness would show deficiencies in the habituation and prepulse inhibition of the startle reflex, similar to those seen with schizophrenics. In two experiments, startle eyeblink EMG was measured in physical anhedonics, perceptual aberrators, and normal controls. 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 presented with stimulus onset asynchronies (SOAs) of 60 or 120 msec before startle-eliciting stimuli at intensities of 85 and 100 dB SPL. Inhibition of startle was generally more pronounced when the prestimulus was more intense and at a longer SOA, and when the eliciting stimulus was more intense (for response amplitude). In both experiments, startle responses were larger and more probable for more intense eliciting stimuli. Also, the diagnosis group variable had no significant effect in either experiment. These results demonstrate that college students who produce high scores on scales of psychosis-proneness may not provide a good model for the perceptual gating deficits which have been demonstrated in schizophrenic patients, with regard to automatic measures of stimulus processing.