Evoked response and kinesthetic measures of augmenting/reducing in schizophrenics: replications and extensions

This study represents an attempt to replicate the central results of earlier work on stimulus intensity control. It uses a diverse sample of 40 hospitalized schizophrenic subjects, both chronic and acute. Two measures of stimulus intensity control were used: the Petrie kinesthetic figural aftereffects procedure (KFA), and the EEG method of average evoked response (AER). Finding the earlier results generally applicable, it presents a model of the function of stimulus intensity control in schizophrenia, which suggests that acute schizophrenics are particularly vulnerable to being inundated by stimuli, and therefore, that in order to protect themselves, they tend to reduce the perceived intensity of stimuli. Chronic schizophreniics have higher AER amplitudes and reduce less than acutes, suggesting that among chronics, the reducing mechanism either never was present or failed, whereas paranoid schizophrenics tend to be augmenters--a response style consistent with vigilant scanning.