Thirteen treatment-refractory schizophrenic patients participated in a
haloperidol reduction study. Two of the subjects were unable to tolerate
medication reduction. These subjects were comparable to the other patients
in terms of initial clinical variables but were outliers on baseline
accuracy and reaction time measures from the Span of Apprehension. The
results suggest that aspects of basic visual processing and motor response
speed may identify patients who require higher neuroleptic doses.